Per destination latest image tag

We tag the deployed image with the latest image tag when deploying. But
if we are deploying multiple destinations to the same host they'll
conflict with each other.

.github/workflows/ci.yml

@@ -0,0 +1,61 @@
+name: CI
+on:
+  push:
+    branches:
+      - main
+  pull_request:
+jobs:
+  rubocop:
+    name: RuboCop
+    runs-on: ubuntu-latest
+    env:
+      BUNDLE_ONLY: rubocop
+    steps:
+      - name: Checkout code
+        uses: actions/checkout@v4
+      - name: Setup Ruby and install gems
+        uses: ruby/setup-ruby@v1
+        with:
+          ruby-version: 3.3.0
+          bundler-cache: true
+      - name: Run Rubocop
+        run: bundle exec rubocop --parallel
+  tests:
+    strategy:
+      matrix:
+        ruby-version:
+          - "2.7"
+          - "3.1"
+          - "3.2"
+          - "3.3"
+        gemfile:
+          - Gemfile
+          - gemfiles/ruby_2.7.gemfile
+          - gemfiles/rails_edge.gemfile
+        exclude:
+          - ruby-version: "2.7"
+            gemfile: Gemfile
+          - ruby-version: "2.7"
+            gemfile: gemfiles/rails_edge.gemfile
+          - ruby-version: "3.1"
+            gemfile: gemfiles/ruby_2.7.gemfile
+          - ruby-version: "3.2"
+            gemfile: gemfiles/ruby_2.7.gemfile
+          - ruby-version: "3.3"
+            gemfile: gemfiles/ruby_2.7.gemfile
+    name: ${{ format('Tests (Ruby {0})', matrix.ruby-version) }}
+    runs-on: ubuntu-latest
+    continue-on-error: true
+    env:
+      BUNDLE_GEMFILE: ${{ github.workspace }}/${{ matrix.gemfile }}
+    steps:
+      - uses: actions/checkout@v4
+
+      - name: Install Ruby
+        uses: ruby/setup-ruby@v1
+        with:
+          ruby-version: ${{ matrix.ruby-version }}
+          bundler-cache: true
+
+      - name: Run tests
+        run: bin/test

.github/workflows/docker-publish.yml

@@ -0,0 +1,55 @@
+name: Docker
+
+on:
+  workflow_dispatch:
+    inputs:
+      tagInput:
+        description: 'Tag'
+        required: true
+    
+  release:
+    types: [created]
+    tags:
+      - 'v*'
+
+jobs:
+  build-and-push-image:
+    runs-on: ubuntu-latest
+    permissions:
+      contents: read
+      packages: write
+    steps:
+      -
+        name: Checkout
+        uses: actions/checkout@v3
+      -
+        name: Set up QEMU
+        uses: docker/setup-qemu-action@v2
+      -
+        name: Set up Docker Buildx
+        uses: docker/setup-buildx-action@v2
+      -
+        name: Login to GitHub Container Registry
+        uses: docker/login-action@v2
+        with:
+          registry: ghcr.io
+          username: ${{ github.actor }}
+          password: ${{ secrets.GITHUB_TOKEN }}
+      - name: Determine version tag
+        id: version-tag
+        run: |
+          INPUT_VALUE="${{ github.event.inputs.tagInput }}"
+          if [ -z "$INPUT_VALUE" ]; then
+            INPUT_VALUE="${{ github.ref_name }}"
+          fi
+          echo "::set-output name=value::$INPUT_VALUE"
+      -
+        name: Build and push
+        uses: docker/build-push-action@v3
+        with:
+          context: .
+          platforms: linux/amd64,linux/arm64
+          push: true
+          tags: |
+            ghcr.io/basecamp/kamal:latest
+            ghcr.io/basecamp/kamal:${{ steps.version-tag.outputs.value }}

.gitignore

@@ -1,2 +1,5 @@
 .byebug_history
 *.gem
+coverage/*
+.DS_Store
+gemfiles/*.lock

.rubocop.yml

@@ -0,0 +1,2 @@
+inherit_gem:
+  rubocop-rails-omakase: rubocop.yml

CODE_OF_CONDUCT.md

@@ -0,0 +1,41 @@
+# Contributor Code of Conduct
+
+As contributors and maintainers of the Kamal project, we pledge to create a welcoming and inclusive environment for everyone. We value the participation of each member of our community and want all contributors to feel respected and valued.
+
+We are committed to providing a harassment-free experience for everyone, regardless of gender, gender identity and expression, sexual orientation, disability, physical appearance, body size, race, age, or religion (or lack thereof). We do not tolerate harassment of participants in any form.
+
+This code of conduct applies to all Kamal project spaces, including but not limited to project code, issue trackers, chat rooms, and mailing lists. Violations of this code of conduct may result in removal from the project community.
+
+## Our standards
+
+Examples of behavior that contributes to creating a positive environment include:
+
+- Using welcoming and inclusive language
+- Being respectful of differing viewpoints and experiences
+- Gracefully accepting constructive criticism
+- Focusing on what is best for the community
+- Showing empathy towards other community members
+
+Examples of unacceptable behavior by participants include:
+
+- The use of sexualized language or imagery and unwelcome sexual attention or advances
+- Trolling, insulting/derogatory comments, and personal or political attacks
+- Public or private harassment
+- Publishing others' private information, such as a physical or electronic address, without explicit permission
+- Other conduct which could reasonably be considered inappropriate in a professional setting
+
+## Responsibilities
+
+Project maintainers are responsible for clarifying the standards of acceptable behavior and are expected to take appropriate and fair corrective action in response to any instances of unacceptable behavior.
+
+Project maintainers have the right and responsibility to remove, edit, or reject comments, commits, code, wiki edits, issues, and other contributions that are not aligned with this Code of Conduct, or to ban temporarily or permanently any contributor for other behaviors that they deem inappropriate, threatening, offensive, or harmful.
+
+## Reporting
+
+If you are subject to or witness unacceptable behavior, or have any other concerns, please notify a project maintainer. All reports will be kept confidential and will be reviewed and investigated promptly.
+
+We will investigate every complaint and take appropriate action. We reserve the right to remove any content that violates this Code of Conduct, or to temporarily or permanently ban any contributor for other behaviors that we deem inappropriate, threatening, offensive, or harmful.
+
+## Attribution
+
+This Code of Conduct is adapted from the Contributor Covenant, version 1.4, available at <https://www.contributor-covenant.org/version/1/4/code-of-conduct.html>.

CONTRIBUTING.md

@@ -0,0 +1,49 @@
+# Contributing to Kamal development
+
+Thank you for considering contributing to Kamal! This document outlines some guidelines for contributing to this open source project.
+
+Please make sure to review our [Code of Conduct](CODE_OF_CONDUCT.md) before contributing to Kamal.
+
+There are several ways you can contribute to the betterment of the project:
+
+- **Report an issue?** - If the issue isn’t reported, we can’t fix it. Please report any bugs, feature, and/or improvement requests on the [Kamal GitHub Issues tracker](https://github.com/basecamp/kamal/issues).
+- **Submit patches** - Do you have a new feature or a fix you'd like to share? [Submit a pull request](https://github.com/basecamp/kamal/pulls)!
+- **Write blog articles** - Are you using Kamal? We'd love to hear how you're using it with your projects. Write a tutorial and post it on your blog!
+
+## Issues
+
+If you encounter any issues with the project, please check the [existing issues](https://github.com/basecamp/kamal/issues) first to see if the issue has already been reported. If the issue hasn't been reported, please open a new issue with a clear description of the problem and steps to reproduce it.
+
+## Pull Requests
+
+Please keep the following guidelines in mind when opening a pull request:
+
+- Ensure that your code passes the project's minitests by running ./bin/test.
+- Provide a clear and detailed description of your changes.
+- Keep your changes focused on a single concern.
+- Write clean and readable code that follows the project's code style.
+- Use descriptive variable and function names.
+- Write clear and concise commit messages.
+- Add tests for your changes, if possible.
+- Ensure that your changes don't break existing functionality.
+
+#### Commit message guidelines
+
+A good commit message should describe what changed and why.
+
+## Development
+
+The `main` branch is regularly built and tested, but it is not guaranteed to be completely stable. Tags are created regularly from release branches to indicate new official, stable release versions of Kamal.
+
+Kamal is written in Ruby. You should have Ruby 3.2+ installed on your machine in order to work on Kamal. If that's already setup, run `bundle` in the root directory to install all dependencies. Then you can run `bin/test` to run all tests.
+
+1. Fork the project repository.
+2. Create a new branch for your contribution.
+3. Write your code or make the desired changes.
+4. **Ensure that your code passes the project's minitests by running ./bin/test.**
+5. Commit your changes and push them to your forked repository.
+6. [Open a pull request](https://github.com/basecamp/kamal/pulls) to the main project repository with a detailed description of your changes.
+
+## License
+
+Kamal is released under the MIT License. By contributing to this project, you agree to license your contributions under the same license.

Dockerfile

@@ -0,0 +1,40 @@
+# Use the official Ruby 3.2.0 Alpine image as the base image
+FROM ruby:3.2.0-alpine
+
+# Install  docker/buildx-bin
+COPY --from=docker/buildx-bin /buildx /usr/libexec/docker/cli-plugins/docker-buildx
+
+# Set the working directory to /kamal
+WORKDIR /kamal
+
+# Copy the Gemfile, Gemfile.lock into the container
+COPY Gemfile Gemfile.lock kamal.gemspec ./
+
+# Required in kamal.gemspec
+COPY lib/kamal/version.rb /kamal/lib/kamal/version.rb
+
+# Install system dependencies
+RUN apk add --no-cache --update build-base git docker openrc openssh-client-default \
+    && rc-update add docker boot \
+    && gem install bundler --version=2.4.3 \
+    && bundle install
+
+# Copy the rest of our application code into the container.
+# We do this after bundle install, to avoid having to run bundle
+# every time we do small fixes in the source code.
+COPY . .
+
+# Install the gem locally from the project folder
+RUN gem build kamal.gemspec && \
+    gem install ./kamal-*.gem --no-document
+
+# Set the working directory to /workdir
+WORKDIR /workdir
+
+# Tell git it's safe to access /workdir/.git even if
+# the directory is owned by a different user
+RUN git config --global --add safe.directory /workdir
+
+# Set the entrypoint to run the installed binary in /workdir
+# Example:  docker run -it -v "$PWD:/workdir" kamal init
+ENTRYPOINT ["kamal"]

Gemfile

@@ -1,9 +1,8 @@
-source 'https://rubygems.org'
+source "https://rubygems.org"
 git_source(:github) { |repo| "https://github.com/#{repo}.git" }
 
-# Specify your gem's dependencies in importmap-rails.gemspec.
 gemspec
 
-group :test do
-  gem "byebug"
+group :rubocop do
+  gem "rubocop-rails-omakase", require: false
 end

Gemfile.lock

@@ -1,84 +1,179 @@
 PATH
   remote: .
   specs:
-    mrsk (0.0.1)
-      railties (>= 7.0.0)
+    kamal (1.4.0)
+      activesupport (>= 7.0)
+      base64 (~> 0.2)
+      bcrypt_pbkdf (~> 1.0)
+      concurrent-ruby (~> 1.2)
+      dotenv (~> 2.8)
+      ed25519 (~> 1.2)
+      net-ssh (~> 7.0)
       sshkit (~> 1.21)
+      thor (~> 1.2)
+      zeitwerk (~> 2.5)
 
 GEM
   remote: https://rubygems.org/
   specs:
-    actionpack (7.0.4)
-      actionview (= 7.0.4)
-      activesupport (= 7.0.4)
-      rack (~> 2.0, >= 2.2.0)
+    actionpack (7.1.2)
+      actionview (= 7.1.2)
+      activesupport (= 7.1.2)
+      nokogiri (>= 1.8.5)
+      racc
+      rack (>= 2.2.4)
+      rack-session (>= 1.0.1)
       rack-test (>= 0.6.3)
-      rails-dom-testing (~> 2.0)
-      rails-html-sanitizer (~> 1.0, >= 1.2.0)
-    actionview (7.0.4)
-      activesupport (= 7.0.4)
+      rails-dom-testing (~> 2.2)
+      rails-html-sanitizer (~> 1.6)
+    actionview (7.1.2)
+      activesupport (= 7.1.2)
       builder (~> 3.1)
-      erubi (~> 1.4)
-      rails-dom-testing (~> 2.0)
-      rails-html-sanitizer (~> 1.1, >= 1.2.0)
-    activesupport (7.0.4)
+      erubi (~> 1.11)
+      rails-dom-testing (~> 2.2)
+      rails-html-sanitizer (~> 1.6)
+    activesupport (7.1.2)
+      base64
+      bigdecimal
       concurrent-ruby (~> 1.0, >= 1.0.2)
+      connection_pool (>= 2.2.5)
+      drb
       i18n (>= 1.6, < 2)
       minitest (>= 5.1)
+      mutex_m
       tzinfo (~> 2.0)
+    ast (2.4.2)
+    base64 (0.2.0)
+    bcrypt_pbkdf (1.1.0)
+    bigdecimal (3.1.5)
     builder (3.2.4)
-    byebug (11.1.3)
-    concurrent-ruby (1.1.10)
+    concurrent-ruby (1.2.2)
+    connection_pool (2.4.1)
     crass (1.0.6)
+    debug (1.9.1)
+      irb (~> 1.10)
+      reline (>= 0.3.8)
+    dotenv (2.8.1)
+    drb (2.2.0)
+      ruby2_keywords
+    ed25519 (1.3.0)
     erubi (1.12.0)
-    i18n (1.12.0)
+    i18n (1.14.1)
       concurrent-ruby (~> 1.0)
-    loofah (2.19.1)
+    io-console (0.7.1)
+    irb (1.11.0)
+      rdoc
+      reline (>= 0.3.8)
+    json (2.7.1)
+    language_server-protocol (3.17.0.3)
+    loofah (2.22.0)
       crass (~> 1.0.2)
-      nokogiri (>= 1.5.9)
-    method_source (1.0.0)
-    minitest (5.17.0)
+      nokogiri (>= 1.12.0)
+    minitest (5.20.0)
+    mocha (2.1.0)
+      ruby2_keywords (>= 0.0.5)
+    mutex_m (0.2.0)
     net-scp (4.0.0)
       net-ssh (>= 2.6.5, < 8.0.0)
-    net-ssh (7.0.1)
-    nokogiri (1.13.10-arm64-darwin)
+    net-ssh (7.2.1)
+    nokogiri (1.16.0-arm64-darwin)
       racc (~> 1.4)
-    racc (1.6.2)
-    rack (2.2.5)
-    rack-test (2.0.2)
+    nokogiri (1.16.0-x86_64-darwin)
+      racc (~> 1.4)
+    nokogiri (1.16.0-x86_64-linux)
+      racc (~> 1.4)
+    parallel (1.24.0)
+    parser (3.3.0.5)
+      ast (~> 2.4.1)
+      racc
+    psych (5.1.2)
+      stringio
+    racc (1.7.3)
+    rack (3.0.8)
+    rack-session (2.0.0)
+      rack (>= 3.0.0)
+    rack-test (2.1.0)
       rack (>= 1.3)
-    rails-dom-testing (2.0.3)
-      activesupport (>= 4.2.0)
+    rackup (2.1.0)
+      rack (>= 3)
+      webrick (~> 1.8)
+    rails-dom-testing (2.2.0)
+      activesupport (>= 5.0.0)
+      minitest
       nokogiri (>= 1.6)
-    rails-html-sanitizer (1.4.4)
-      loofah (~> 2.19, >= 2.19.1)
-    railties (7.0.4)
-      actionpack (= 7.0.4)
-      activesupport (= 7.0.4)
-      method_source
+    rails-html-sanitizer (1.6.0)
+      loofah (~> 2.21)
+      nokogiri (~> 1.14)
+    railties (7.1.2)
+      actionpack (= 7.1.2)
+      activesupport (= 7.1.2)
+      irb
+      rackup (>= 1.0.0)
       rake (>= 12.2)
-      thor (~> 1.0)
-      zeitwerk (~> 2.5)
-    rake (13.0.6)
-    sshkit (1.21.3)
+      thor (~> 1.0, >= 1.2.2)
+      zeitwerk (~> 2.6)
+    rainbow (3.1.1)
+    rake (13.1.0)
+    rdoc (6.6.2)
+      psych (>= 4.0.0)
+    regexp_parser (2.9.0)
+    reline (0.4.2)
+      io-console (~> 0.5)
+    rexml (3.2.6)
+    rubocop (1.62.1)
+      json (~> 2.3)
+      language_server-protocol (>= 3.17.0)
+      parallel (~> 1.10)
+      parser (>= 3.3.0.2)
+      rainbow (>= 2.2.2, < 4.0)
+      regexp_parser (>= 1.8, < 3.0)
+      rexml (>= 3.2.5, < 4.0)
+      rubocop-ast (>= 1.31.1, < 2.0)
+      ruby-progressbar (~> 1.7)
+      unicode-display_width (>= 2.4.0, < 3.0)
+    rubocop-ast (1.31.2)
+      parser (>= 3.3.0.4)
+    rubocop-minitest (0.35.0)
+      rubocop (>= 1.61, < 2.0)
+      rubocop-ast (>= 1.31.1, < 2.0)
+    rubocop-performance (1.20.2)
+      rubocop (>= 1.48.1, < 2.0)
+      rubocop-ast (>= 1.30.0, < 2.0)
+    rubocop-rails (2.24.0)
+      activesupport (>= 4.2.0)
+      rack (>= 1.1)
+      rubocop (>= 1.33.0, < 2.0)
+      rubocop-ast (>= 1.31.1, < 2.0)
+    rubocop-rails-omakase (1.0.0)
+      rubocop
+      rubocop-minitest
+      rubocop-performance
+      rubocop-rails
+    ruby-progressbar (1.13.0)
+    ruby2_keywords (0.0.5)
+    sshkit (1.21.7)
+      mutex_m
       net-scp (>= 1.1.2)
       net-ssh (>= 2.8.0)
-    thor (1.2.1)
-    tzinfo (2.0.5)
+    stringio (3.1.0)
+    thor (1.3.0)
+    tzinfo (2.0.6)
       concurrent-ruby (~> 1.0)
-    zeitwerk (2.6.6)
+    unicode-display_width (2.5.0)
+    webrick (1.8.1)
+    zeitwerk (2.6.12)
 
 PLATFORMS
-  arm64-darwin-20
-  arm64-darwin-21
-  arm64-darwin-22
-  x86_64-darwin-20
-  x86_64-darwin-21
+  arm64-darwin
+  x86_64-darwin
   x86_64-linux
 
 DEPENDENCIES
-  byebug
-  mrsk!
+  debug
+  kamal!
+  mocha
+  railties
+  rubocop-rails-omakase
 
 BUNDLED WITH
-   2.2.33
+   2.4.3

README.md

@@ -1,55 +1,13 @@
-# MRSK
+# Kamal: Deploy web apps anywhere
 
-MRSK lets you do zero-downtime deploys of Rails apps packed as containers to any host running Docker. It uses the dynamic reverse-proxy Traefik to hold requests while the new application container is started and the old one is wound down. It works across multiple hosts at the same time, using SSHKit to execute commands.
+From bare metal to cloud VMs, deploy web apps anywhere with zero downtime. Kamal has the dynamic reverse-proxy Traefik hold requests while a new app container is started and the old one is stopped. Works seamlessly across multiple hosts, using SSHKit to execute commands. Originally built for Rails apps, Kamal will work with any type of web app that can be containerized with Docker.
 
-## Installation
+➡️ See [kamal-deploy.org](https://kamal-deploy.org) for documentation on [installation](https://kamal-deploy.org/docs/installation), [configuration](https://kamal-deploy.org/docs/configuration), and [commands](https://kamal-deploy.org/docs/commands).
 
-Create a configuration file for MRSK in `config/deploy.yml` that looks like this:
+## Contributing to the documentation
 
-```yaml
-service: my-app
-image: name/my-app
-servers:
-  - xxx.xxx.xxx.xxx
-  - xxx.xxx.xxx.xxx
-env:
-  DATABASE_URL: mysql2://username@localhost/database_name/
-  REDIS_URL: redis://host:6379/1
-```
-
-Then first login to the Docker Hub registry on the servers:
-
-```
-rake mrsk:registry:login DOCKER_USER=name DOCKER_PASSWORD=pw
-```
-
-Now you're ready to deploy a multi-arch image (FIXME: currently you need to manually run `docker buildx create --use` once first):
-
-```
-rake mrsk:deploy
-```
-
-This will:
-
-1. Build the image using the standard Dockerfile in the root of the application.
-2. Push the image to the registry.
-3. Pull the image on all the servers.
-4. Ensure Traefik is running and accepting traffic on port 80.
-5. Stop any containers running a previous versions of the app.
-6. Start a new container with the version of the app that matches the current git version hash.
-
-Voila! All the servers are now serving the app on port 80, and you're ready to put them behind a load balancer to serve live traffic.
-
-## Stage of development
-
-This is alpha software. Lots of stuff is missing. Here are some of the areas we seek to improve:
-
-- Use of other registries than Docker Hub
-- Adapterize commands to work with Podman and other container runners
-- Better flow for secrets and ENV
-- Possibly switching to a bin/mrsk command rather than raw rake
-- Integrate wirmth cloud CI pipelines
+Please help us improve Kamal's documentation on the [the basecamp/kamal-site repository](https://github.com/basecamp/kamal-site).
 
 ## License
 
-Mrsk is released under the [MIT License](https://opensource.org/licenses/MIT).
+Kamal is released under the [MIT License](https://opensource.org/licenses/MIT).

bin/kamal

@@ -0,0 +1,18 @@
+#!/usr/bin/env ruby
+
+# Prevent failures from being reported twice.
+Thread.report_on_exception = false
+
+require "kamal"
+
+begin
+  Kamal::Cli::Main.start(ARGV)
+rescue SSHKit::Runner::ExecuteError => e
+  puts "  \e[31mERROR (#{e.cause.class}): #{e.message}\e[0m"
+  puts e.cause.backtrace if ENV["VERBOSE"]
+  exit 1
+rescue => e
+  puts "  \e[31mERROR (#{e.class}): #{e.message}\e[0m"
+  puts e.backtrace if ENV["VERBOSE"]
+  exit 1
+end

bin/release

@@ -2,13 +2,13 @@
 
 VERSION=$1
 
-printf "module Mrsk\n  VERSION = \"$VERSION\"\nend\n" > ./lib/mrsk/version.rb
+printf "module Kamal\n  VERSION = \"$VERSION\"\nend\n" > ./lib/kamal/version.rb
 bundle
-git add Gemfile.lock lib/mrsk/version.rb
+git add Gemfile.lock lib/kamal/version.rb
 git commit -m "Bump version for $VERSION"
 git push
 git tag v$VERSION
 git push --tags
-gem build mrsk.gemspec
-gem push "mrsk-$VERSION.gem" --host https://rubygems.org
-rm "mrsk-$VERSION.gem"
+gem build kamal.gemspec
+gem push "kamal-$VERSION.gem" --host https://rubygems.org
+rm "kamal-$VERSION.gem"

gemfiles/rails_edge.gemfile

@@ -0,0 +1,9 @@
+source 'https://rubygems.org'
+git_source(:github) { |repo| "https://github.com/#{repo}.git" }
+
+git "https://github.com/rails/rails.git" do
+  gem "railties"
+  gem "activesupport"
+end
+
+gemspec path: "../"

gemfiles/ruby_2.7.gemfile

@@ -0,0 +1,6 @@
+source 'https://rubygems.org'
+git_source(:github) { |repo| "https://github.com/#{repo}.git" }
+
+gemspec path: "../"
+
+gem "nokogiri", "~> 1.15.0"

kamal.gemspec

@@ -0,0 +1,28 @@
+require_relative "lib/kamal/version"
+
+Gem::Specification.new do |spec|
+  spec.name        = "kamal"
+  spec.version     = Kamal::VERSION
+  spec.authors     = [ "David Heinemeier Hansson" ]
+  spec.email       = "dhh@hey.com"
+  spec.homepage    = "https://github.com/basecamp/kamal"
+  spec.summary     = "Deploy web apps in containers to servers running Docker with zero downtime."
+  spec.license     = "MIT"
+  spec.files = Dir["lib/**/*", "MIT-LICENSE", "README.md"]
+  spec.executables = %w[ kamal ]
+
+  spec.add_dependency "activesupport", ">= 7.0"
+  spec.add_dependency "sshkit", "~> 1.21"
+  spec.add_dependency "net-ssh", "~> 7.0"
+  spec.add_dependency "thor", "~> 1.2"
+  spec.add_dependency "dotenv", "~> 2.8"
+  spec.add_dependency "zeitwerk", "~> 2.5"
+  spec.add_dependency "ed25519", "~> 1.2"
+  spec.add_dependency "bcrypt_pbkdf", "~> 1.0"
+  spec.add_dependency "concurrent-ruby", "~> 1.2"
+  spec.add_dependency "base64", "~> 0.2"
+
+  spec.add_development_dependency "debug"
+  spec.add_development_dependency "mocha"
+  spec.add_development_dependency "railties"
+end

lib/kamal.rb

@@ -0,0 +1,10 @@
+module Kamal
+end
+
+require "active_support"
+require "zeitwerk"
+
+loader = Zeitwerk::Loader.for_gem
+loader.ignore("#{__dir__}/kamal/sshkit_with_ext.rb")
+loader.setup
+loader.eager_load # We need all commands loaded.

lib/kamal/cli.rb

@@ -0,0 +1,7 @@
+module Kamal::Cli
+  class LockError < StandardError; end
+  class HookError < StandardError; end
+end
+
+# SSHKit uses instance eval, so we need a global const for ergonomics
+KAMAL = Kamal::Commander.new

lib/kamal/cli/accessory.rb

@@ -0,0 +1,252 @@
+class Kamal::Cli::Accessory < Kamal::Cli::Base
+  desc "boot [NAME]", "Boot new accessory service on host (use NAME=all to boot all accessories)"
+  def boot(name, login: true)
+    mutating do
+      if name == "all"
+        KAMAL.accessory_names.each { |accessory_name| boot(accessory_name) }
+      else
+        with_accessory(name) do |accessory, hosts|
+          directories(name)
+          upload(name)
+
+          on(hosts) do
+            execute *KAMAL.registry.login if login
+            execute *KAMAL.auditor.record("Booted #{name} accessory"), verbosity: :debug
+            execute *accessory.run
+          end
+        end
+      end
+    end
+  end
+
+  desc "upload [NAME]", "Upload accessory files to host", hide: true
+  def upload(name)
+    mutating do
+      with_accessory(name) do |accessory, hosts|
+        on(hosts) do
+          accessory.files.each do |(local, remote)|
+            accessory.ensure_local_file_present(local)
+
+            execute *accessory.make_directory_for(remote)
+            upload! local, remote
+            execute :chmod, "755", remote
+          end
+        end
+      end
+    end
+  end
+
+  desc "directories [NAME]", "Create accessory directories on host", hide: true
+  def directories(name)
+    mutating do
+      with_accessory(name) do |accessory, hosts|
+        on(hosts) do
+          accessory.directories.keys.each do |host_path|
+            execute *accessory.make_directory(host_path)
+          end
+        end
+      end
+    end
+  end
+
+  desc "reboot [NAME]", "Reboot existing accessory on host (stop container, remove container, start new container; use NAME=all to boot all accessories)"
+  def reboot(name)
+    mutating do
+      if name == "all"
+        KAMAL.accessory_names.each { |accessory_name| reboot(accessory_name) }
+      else
+        with_accessory(name) do |accessory, hosts|
+          on(hosts) do
+            execute *KAMAL.registry.login
+          end
+
+          stop(name)
+          remove_container(name)
+          boot(name, login: false)
+        end
+      end
+    end
+  end
+
+  desc "start [NAME]", "Start existing accessory container on host"
+  def start(name)
+    mutating do
+      with_accessory(name) do |accessory, hosts|
+        on(hosts) do
+          execute *KAMAL.auditor.record("Started #{name} accessory"), verbosity: :debug
+          execute *accessory.start
+        end
+      end
+    end
+  end
+
+  desc "stop [NAME]", "Stop existing accessory container on host"
+  def stop(name)
+    mutating do
+      with_accessory(name) do |accessory, hosts|
+        on(hosts) do
+          execute *KAMAL.auditor.record("Stopped #{name} accessory"), verbosity: :debug
+          execute *accessory.stop, raise_on_non_zero_exit: false
+        end
+      end
+    end
+  end
+
+  desc "restart [NAME]", "Restart existing accessory container on host"
+  def restart(name)
+    mutating do
+      with_accessory(name) do
+        stop(name)
+        start(name)
+      end
+    end
+  end
+
+  desc "details [NAME]", "Show details about accessory on host (use NAME=all to show all accessories)"
+  def details(name)
+    if name == "all"
+      KAMAL.accessory_names.each { |accessory_name| details(accessory_name) }
+    else
+      with_accessory(name) do |accessory, hosts|
+        on(hosts) { puts capture_with_info(*accessory.info) }
+      end
+    end
+  end
+
+  desc "exec [NAME] [CMD]", "Execute a custom command on servers (use --help to show options)"
+  option :interactive, aliases: "-i", type: :boolean, default: false, desc: "Execute command over ssh for an interactive shell (use for console/bash)"
+  option :reuse, type: :boolean, default: false, desc: "Reuse currently running container instead of starting a new one"
+  def exec(name, cmd)
+    with_accessory(name) do |accessory, hosts|
+      case
+      when options[:interactive] && options[:reuse]
+        say "Launching interactive command with via SSH from existing container...", :magenta
+        run_locally { exec accessory.execute_in_existing_container_over_ssh(cmd) }
+
+      when options[:interactive]
+        say "Launching interactive command via SSH from new container...", :magenta
+        run_locally { exec accessory.execute_in_new_container_over_ssh(cmd) }
+
+      when options[:reuse]
+        say "Launching command from existing container...", :magenta
+        on(hosts) do
+          execute *KAMAL.auditor.record("Executed cmd '#{cmd}' on #{name} accessory"), verbosity: :debug
+          capture_with_info(*accessory.execute_in_existing_container(cmd))
+        end
+
+      else
+        say "Launching command from new container...", :magenta
+        on(hosts) do
+          execute *KAMAL.auditor.record("Executed cmd '#{cmd}' on #{name} accessory"), verbosity: :debug
+          capture_with_info(*accessory.execute_in_new_container(cmd))
+        end
+      end
+    end
+  end
+
+  desc "logs [NAME]", "Show log lines from accessory on host (use --help to show options)"
+  option :since, aliases: "-s", desc: "Show logs since timestamp (e.g. 2013-01-02T13:23:37Z) or relative (e.g. 42m for 42 minutes)"
+  option :lines, type: :numeric, aliases: "-n", desc: "Number of log lines to pull from each server"
+  option :grep, aliases: "-g", desc: "Show lines with grep match only (use this to fetch specific requests by id)"
+  option :follow, aliases: "-f", desc: "Follow logs on primary server (or specific host set by --hosts)"
+  def logs(name)
+    with_accessory(name) do |accessory, hosts|
+      grep = options[:grep]
+
+      if options[:follow]
+        run_locally do
+          info "Following logs on #{hosts}..."
+          info accessory.follow_logs(grep: grep)
+          exec accessory.follow_logs(grep: grep)
+        end
+      else
+        since = options[:since]
+        lines = options[:lines].presence || ((since || grep) ? nil : 100) # Default to 100 lines if since or grep isn't set
+
+        on(hosts) do
+          puts capture_with_info(*accessory.logs(since: since, lines: lines, grep: grep))
+        end
+      end
+    end
+  end
+
+  desc "remove [NAME]", "Remove accessory container, image and data directory from host (use NAME=all to remove all accessories)"
+  option :confirmed, aliases: "-y", type: :boolean, default: false, desc: "Proceed without confirmation question"
+  def remove(name)
+    mutating do
+      if name == "all"
+        KAMAL.accessory_names.each { |accessory_name| remove(accessory_name) }
+      else
+        confirming "This will remove all containers, images and data directories for #{name}. Are you sure?" do
+          with_accessory(name) do
+            stop(name)
+            remove_container(name)
+            remove_image(name)
+            remove_service_directory(name)
+          end
+        end
+      end
+    end
+  end
+
+  desc "remove_container [NAME]", "Remove accessory container from host", hide: true
+  def remove_container(name)
+    mutating do
+      with_accessory(name) do |accessory, hosts|
+        on(hosts) do
+          execute *KAMAL.auditor.record("Remove #{name} accessory container"), verbosity: :debug
+          execute *accessory.remove_container
+        end
+      end
+    end
+  end
+
+  desc "remove_image [NAME]", "Remove accessory image from host", hide: true
+  def remove_image(name)
+    mutating do
+      with_accessory(name) do |accessory, hosts|
+        on(hosts) do
+          execute *KAMAL.auditor.record("Removed #{name} accessory image"), verbosity: :debug
+          execute *accessory.remove_image
+        end
+      end
+    end
+  end
+
+  desc "remove_service_directory [NAME]", "Remove accessory directory used for uploaded files and data directories from host", hide: true
+  def remove_service_directory(name)
+    mutating do
+      with_accessory(name) do |accessory, hosts|
+        on(hosts) do
+          execute *accessory.remove_service_directory
+        end
+      end
+    end
+  end
+
+  private
+    def with_accessory(name)
+      if KAMAL.config.accessory(name)
+        accessory = KAMAL.accessory(name)
+        yield accessory, accessory_hosts(accessory)
+      else
+        error_on_missing_accessory(name)
+      end
+    end
+
+    def error_on_missing_accessory(name)
+      options = KAMAL.accessory_names.presence
+
+      error \
+        "No accessory by the name of '#{name}'" +
+        (options ? " (options: #{options.to_sentence})" : "")
+    end
+
+    def accessory_hosts(accessory)
+      if KAMAL.specific_hosts&.any?
+        KAMAL.specific_hosts & accessory.hosts
+      else
+        accessory.hosts
+      end
+    end
+end

lib/kamal/cli/app.rb

@@ -0,0 +1,289 @@
+class Kamal::Cli::App < Kamal::Cli::Base
+  desc "boot", "Boot app on servers (or reboot app if already running)"
+  def boot
+    mutating do
+      hold_lock_on_error do
+        say "Get most recent version available as an image...", :magenta unless options[:version]
+        using_version(version_or_latest) do |version|
+          say "Start container with version #{version} using a #{KAMAL.config.readiness_delay}s readiness delay (or reboot if already running)...", :magenta
+
+          # Assets are prepared in a separate step to ensure they are on all hosts before booting
+          on(KAMAL.hosts) do
+            execute *KAMAL.auditor.record("Tagging #{KAMAL.config.absolute_image} as the latest image"), verbosity: :debug
+            execute *KAMAL.app.tag_current_image_as_latest
+
+            KAMAL.roles_on(host).each do |role|
+              Kamal::Cli::App::PrepareAssets.new(host, role, self).run
+            end
+          end
+
+          on(KAMAL.hosts, **KAMAL.boot_strategy) do |host|
+            KAMAL.roles_on(host).each do |role|
+              Kamal::Cli::App::Boot.new(host, role, version, self).run
+            end
+          end
+        end
+      end
+    end
+  end
+
+  desc "start", "Start existing app container on servers"
+  def start
+    mutating do
+      on(KAMAL.hosts) do |host|
+        roles = KAMAL.roles_on(host)
+
+        roles.each do |role|
+          execute *KAMAL.auditor.record("Started app version #{KAMAL.config.version}"), verbosity: :debug
+          execute *KAMAL.app(role: role).start, raise_on_non_zero_exit: false
+        end
+      end
+    end
+  end
+
+  desc "stop", "Stop app container on servers"
+  def stop
+    mutating do
+      on(KAMAL.hosts) do |host|
+        roles = KAMAL.roles_on(host)
+
+        roles.each do |role|
+          execute *KAMAL.auditor.record("Stopped app", role: role), verbosity: :debug
+          execute *KAMAL.app(role: role).stop, raise_on_non_zero_exit: false
+        end
+      end
+    end
+  end
+
+  # FIXME: Drop in favor of just containers?
+  desc "details", "Show details about app containers"
+  def details
+    on(KAMAL.hosts) do |host|
+      roles = KAMAL.roles_on(host)
+
+      roles.each do |role|
+        puts_by_host host, capture_with_info(*KAMAL.app(role: role).info)
+      end
+    end
+  end
+
+  desc "exec [CMD]", "Execute a custom command on servers (use --help to show options)"
+  option :interactive, aliases: "-i", type: :boolean, default: false, desc: "Execute command over ssh for an interactive shell (use for console/bash)"
+  option :reuse, type: :boolean, default: false, desc: "Reuse currently running container instead of starting a new one"
+  def exec(cmd)
+    case
+    when options[:interactive] && options[:reuse]
+      say "Get current version of running container...", :magenta unless options[:version]
+      using_version(options[:version] || current_running_version) do |version|
+        say "Launching interactive command with version #{version} via SSH from existing container on #{KAMAL.primary_host}...", :magenta
+        run_locally { exec KAMAL.app(role: KAMAL.primary_role).execute_in_existing_container_over_ssh(cmd, host: KAMAL.primary_host) }
+      end
+
+    when options[:interactive]
+      say "Get most recent version available as an image...", :magenta unless options[:version]
+      using_version(version_or_latest) do |version|
+        say "Launching interactive command with version #{version} via SSH from new container on #{KAMAL.primary_host}...", :magenta
+        run_locally do
+          exec KAMAL.app(role: KAMAL.primary_role).execute_in_new_container_over_ssh(cmd, host: KAMAL.primary_host)
+        end
+      end
+
+    when options[:reuse]
+      say "Get current version of running container...", :magenta unless options[:version]
+      using_version(options[:version] || current_running_version) do |version|
+        say "Launching command with version #{version} from existing container...", :magenta
+
+        on(KAMAL.hosts) do |host|
+          roles = KAMAL.roles_on(host)
+
+          roles.each do |role|
+            execute *KAMAL.auditor.record("Executed cmd '#{cmd}' on app version #{version}", role: role), verbosity: :debug
+            puts_by_host host, capture_with_info(*KAMAL.app(role: role).execute_in_existing_container(cmd))
+          end
+        end
+      end
+
+    else
+      say "Get most recent version available as an image...", :magenta unless options[:version]
+      using_version(version_or_latest) do |version|
+        say "Launching command with version #{version} from new container...", :magenta
+        on(KAMAL.hosts) do |host|
+          roles = KAMAL.roles_on(host)
+
+          roles.each do |role|
+            execute *KAMAL.auditor.record("Executed cmd '#{cmd}' on app version #{version}"), verbosity: :debug
+            puts_by_host host, capture_with_info(*KAMAL.app(role: role).execute_in_new_container(cmd))
+          end
+        end
+      end
+    end
+  end
+
+  desc "containers", "Show app containers on servers"
+  def containers
+    on(KAMAL.hosts) { |host| puts_by_host host, capture_with_info(*KAMAL.app.list_containers) }
+  end
+
+  desc "stale_containers", "Detect app stale containers"
+  option :stop, aliases: "-s", type: :boolean, default: false, desc: "Stop the stale containers found"
+  def stale_containers
+    mutating do
+      stop = options[:stop]
+
+      cli = self
+
+      on(KAMAL.hosts) do |host|
+        roles = KAMAL.roles_on(host)
+
+        roles.each do |role|
+          cli.send(:stale_versions, host: host, role: role).each do |version|
+            if stop
+              puts_by_host host, "Stopping stale container for role #{role} with version #{version}"
+              execute *KAMAL.app(role: role).stop(version: version), raise_on_non_zero_exit: false
+            else
+              puts_by_host host,  "Detected stale container for role #{role} with version #{version} (use `kamal app stale_containers --stop` to stop)"
+            end
+          end
+        end
+      end
+    end
+  end
+
+  desc "images", "Show app images on servers"
+  def images
+    on(KAMAL.hosts) { |host| puts_by_host host, capture_with_info(*KAMAL.app.list_images) }
+  end
+
+  desc "logs", "Show log lines from app on servers (use --help to show options)"
+  option :since, aliases: "-s", desc: "Show lines since timestamp (e.g. 2013-01-02T13:23:37Z) or relative (e.g. 42m for 42 minutes)"
+  option :lines, type: :numeric, aliases: "-n", desc: "Number of lines to show from each server"
+  option :grep, aliases: "-g", desc: "Show lines with grep match only (use this to fetch specific requests by id)"
+  option :follow, aliases: "-f", desc: "Follow log on primary server (or specific host set by --hosts)"
+  def logs
+    # FIXME: Catch when app containers aren't running
+
+    grep = options[:grep]
+    since = options[:since]
+    if options[:follow]
+      lines = options[:lines].presence || ((since || grep) ? nil : 10) # Default to 10 lines if since or grep isn't set
+
+      run_locally do
+        info "Following logs on #{KAMAL.primary_host}..."
+
+        KAMAL.specific_roles ||= [ "web" ]
+        role = KAMAL.roles_on(KAMAL.primary_host).first
+
+        info KAMAL.app(role: role).follow_logs(host: KAMAL.primary_host, lines: lines, grep: grep)
+        exec KAMAL.app(role: role).follow_logs(host: KAMAL.primary_host, lines: lines, grep: grep)
+      end
+    else
+      lines = options[:lines].presence || ((since || grep) ? nil : 100) # Default to 100 lines if since or grep isn't set
+
+      on(KAMAL.hosts) do |host|
+        roles = KAMAL.roles_on(host)
+
+        roles.each do |role|
+          begin
+            puts_by_host host, capture_with_info(*KAMAL.app(role: role).logs(since: since, lines: lines, grep: grep))
+          rescue SSHKit::Command::Failed
+            puts_by_host host, "Nothing found"
+          end
+        end
+      end
+    end
+  end
+
+  desc "remove", "Remove app containers and images from servers"
+  def remove
+    mutating do
+      stop
+      remove_containers
+      remove_images
+    end
+  end
+
+  desc "remove_container [VERSION]", "Remove app container with given version from servers", hide: true
+  def remove_container(version)
+    mutating do
+      on(KAMAL.hosts) do |host|
+        roles = KAMAL.roles_on(host)
+
+        roles.each do |role|
+          execute *KAMAL.auditor.record("Removed app container with version #{version}", role: role), verbosity: :debug
+          execute *KAMAL.app(role: role).remove_container(version: version)
+        end
+      end
+    end
+  end
+
+  desc "remove_containers", "Remove all app containers from servers", hide: true
+  def remove_containers
+    mutating do
+      on(KAMAL.hosts) do |host|
+        roles = KAMAL.roles_on(host)
+
+        roles.each do |role|
+          execute *KAMAL.auditor.record("Removed all app containers", role: role), verbosity: :debug
+          execute *KAMAL.app(role: role).remove_containers
+        end
+      end
+    end
+  end
+
+  desc "remove_images", "Remove all app images from servers", hide: true
+  def remove_images
+    mutating do
+      on(KAMAL.hosts) do
+        execute *KAMAL.auditor.record("Removed all app images"), verbosity: :debug
+        execute *KAMAL.app.remove_images
+      end
+    end
+  end
+
+  desc "version", "Show app version currently running on servers"
+  def version
+    on(KAMAL.hosts) do |host|
+      role = KAMAL.roles_on(host).first
+      puts_by_host host, capture_with_info(*KAMAL.app(role: role).current_running_version).strip
+    end
+  end
+
+  private
+    def using_version(new_version)
+      if new_version
+        begin
+          old_version = KAMAL.config.version
+          KAMAL.config.version = new_version
+          yield new_version
+        ensure
+          KAMAL.config.version = old_version
+        end
+      else
+        yield KAMAL.config.version
+      end
+    end
+
+    def current_running_version(host: KAMAL.primary_host)
+      version = nil
+      on(host) do
+        role = KAMAL.roles_on(host).first
+        version = capture_with_info(*KAMAL.app(role: role).current_running_version).strip
+      end
+      version.presence
+    end
+
+    def stale_versions(host:, role:)
+      versions = nil
+      on(host) do
+        versions = \
+          capture_with_info(*KAMAL.app(role: role).list_versions, raise_on_non_zero_exit: false)
+          .split("\n")
+          .drop(1)
+      end
+      versions
+    end
+
+    def version_or_latest
+      options[:version] || "latest"
+    end
+end

lib/kamal/cli/app/boot.rb

@@ -0,0 +1,67 @@
+class Kamal::Cli::App::Boot
+  attr_reader :host, :role, :version, :sshkit
+  delegate :execute, :capture_with_info, :info, to: :sshkit
+  delegate :uses_cord?, :assets?, to: :role
+
+  def initialize(host, role, version, sshkit)
+    @host = host
+    @role = role
+    @version = version
+    @sshkit = sshkit
+  end
+
+  def run
+    old_version = old_version_renamed_if_clashing
+
+    start_new_version
+
+    if old_version
+      stop_old_version(old_version)
+    end
+  end
+
+  private
+    def app
+      @app ||= KAMAL.app(role: role)
+    end
+
+    def auditor
+      @auditor = KAMAL.auditor(role: role)
+    end
+
+    def audit(message)
+      execute *auditor.record(message), verbosity: :debug
+    end
+
+    def old_version_renamed_if_clashing
+      if capture_with_info(*app.container_id_for_version(version), raise_on_non_zero_exit: false).present?
+        renamed_version = "#{version}_replaced_#{SecureRandom.hex(8)}"
+        info "Renaming container #{version} to #{renamed_version} as already deployed on #{host}"
+        audit("Renaming container #{version} to #{renamed_version}")
+        execute *app.rename_container(version: version, new_version: renamed_version)
+      end
+
+      capture_with_info(*app.current_running_version, raise_on_non_zero_exit: false).strip.presence
+    end
+
+    def start_new_version
+      audit "Booted app version #{version}"
+      execute *app.tie_cord(role.cord_host_file) if uses_cord?
+      execute *app.run(hostname: "#{host}-#{SecureRandom.hex(6)}")
+      Kamal::Cli::Healthcheck::Poller.wait_for_healthy(pause_after_ready: true) { capture_with_info(*app.status(version: version)) }
+    end
+
+    def stop_old_version(version)
+      if uses_cord?
+        cord = capture_with_info(*app.cord(version: version), raise_on_non_zero_exit: false).strip
+        if cord.present?
+          execute *app.cut_cord(cord)
+          Kamal::Cli::Healthcheck::Poller.wait_for_unhealthy(pause_after_ready: true) { capture_with_info(*app.status(version: version)) }
+        end
+      end
+
+      execute *app.stop(version: version), raise_on_non_zero_exit: false
+
+      execute *app.clean_up_assets if assets?
+    end
+end

lib/kamal/cli/app/prepare_assets.rb

@@ -0,0 +1,24 @@
+class Kamal::Cli::App::PrepareAssets
+  attr_reader :host, :role, :sshkit
+  delegate :execute, :capture_with_info, :info, to: :sshkit
+  delegate :assets?, to: :role
+
+  def initialize(host, role, sshkit)
+    @host = host
+    @role = role
+    @sshkit = sshkit
+  end
+
+  def run
+    if assets?
+      execute *app.extract_assets
+      old_version = capture_with_info(*app.current_running_version, raise_on_non_zero_exit: false).strip
+      execute *app.sync_asset_volumes(old_version: old_version)
+    end
+  end
+
+  private
+    def app
+      @app ||= KAMAL.app(role: role)
+    end
+end

lib/kamal/cli/base.rb

@@ -0,0 +1,195 @@
+require "thor"
+require "dotenv"
+require "kamal/sshkit_with_ext"
+
+module Kamal::Cli
+  class Base < Thor
+    include SSHKit::DSL
+
+    def self.exit_on_failure?() true end
+
+    class_option :verbose, type: :boolean, aliases: "-v", desc: "Detailed logging"
+    class_option :quiet, type: :boolean, aliases: "-q", desc: "Minimal logging"
+
+    class_option :version, desc: "Run commands against a specific app version"
+
+    class_option :primary, type: :boolean, aliases: "-p", desc: "Run commands only on primary host instead of all"
+    class_option :hosts, aliases: "-h", desc: "Run commands on these hosts instead of all (separate by comma, supports wildcards with *)"
+    class_option :roles, aliases: "-r", desc: "Run commands on these roles instead of all (separate by comma, supports wildcards with *)"
+
+    class_option :config_file, aliases: "-c", default: "config/deploy.yml", desc: "Path to config file"
+    class_option :destination, aliases: "-d", desc: "Specify destination to be used for config file (staging -> deploy.staging.yml)"
+
+    class_option :skip_hooks, aliases: "-H", type: :boolean, default: false, desc: "Don't run hooks"
+
+    def initialize(*)
+      super
+      @original_env = ENV.to_h.dup
+      load_envs
+      initialize_commander(options_with_subcommand_class_options)
+    end
+
+    private
+      def load_envs
+        if destination = options[:destination]
+          Dotenv.load(".env.#{destination}", ".env")
+        else
+          Dotenv.load(".env")
+        end
+      end
+
+      def reload_envs
+        ENV.clear
+        ENV.update(@original_env)
+        load_envs
+      end
+
+      def options_with_subcommand_class_options
+        options.merge(@_initializer.last[:class_options] || {})
+      end
+
+      def initialize_commander(options)
+        KAMAL.tap do |commander|
+          if options[:verbose]
+            ENV["VERBOSE"] = "1" # For backtraces via cli/start
+            commander.verbosity = :debug
+          end
+
+          if options[:quiet]
+            commander.verbosity = :error
+          end
+
+          commander.configure \
+            config_file: Pathname.new(File.expand_path(options[:config_file])),
+            destination: options[:destination],
+            version: options[:version]
+
+          commander.specific_hosts    = options[:hosts]&.split(",")
+          commander.specific_roles    = options[:roles]&.split(",")
+          commander.specific_primary! if options[:primary]
+        end
+      end
+
+      def print_runtime
+        started_at = Time.now
+        yield
+        Time.now - started_at
+      ensure
+        runtime = Time.now - started_at
+        puts "  Finished all in #{sprintf("%.1f seconds", runtime)}"
+      end
+
+      def mutating
+        return yield if KAMAL.holding_lock?
+
+        run_hook "pre-connect"
+
+        ensure_run_directory
+
+        acquire_lock
+
+        begin
+          yield
+        rescue
+          if KAMAL.hold_lock_on_error?
+            error "  \e[31mDeploy lock was not released\e[0m"
+          else
+            release_lock
+          end
+
+          raise
+        end
+
+        release_lock
+      end
+
+      def confirming(question)
+        return yield if options[:confirmed]
+
+        if ask(question, limited_to: %w[ y N ], default: "N") == "y"
+          yield
+        else
+          say "Aborted", :red
+        end
+      end
+
+      def acquire_lock
+        raise_if_locked do
+          say "Acquiring the deploy lock...", :magenta
+          on(KAMAL.primary_host) { execute *KAMAL.lock.acquire("Automatic deploy lock", KAMAL.config.version), verbosity: :debug }
+        end
+
+        KAMAL.holding_lock = true
+      end
+
+      def release_lock
+        say "Releasing the deploy lock...", :magenta
+        on(KAMAL.primary_host) { execute *KAMAL.lock.release, verbosity: :debug }
+
+        KAMAL.holding_lock = false
+      end
+
+      def raise_if_locked
+        yield
+      rescue SSHKit::Runner::ExecuteError => e
+        if e.message =~ /cannot create directory/
+          say "Deploy lock already in place!", :red
+          on(KAMAL.primary_host) { puts capture_with_debug(*KAMAL.lock.status) }
+          raise LockError, "Deploy lock found. Run 'kamal lock help' for more information"
+        else
+          raise e
+        end
+      end
+
+      def hold_lock_on_error
+        if KAMAL.hold_lock_on_error?
+          yield
+        else
+          KAMAL.hold_lock_on_error = true
+          yield
+          KAMAL.hold_lock_on_error = false
+        end
+      end
+
+      def run_hook(hook, **extra_details)
+        if !options[:skip_hooks] && KAMAL.hook.hook_exists?(hook)
+          details = { hosts: KAMAL.hosts.join(","), command: command, subcommand: subcommand }
+
+          say "Running the #{hook} hook...", :magenta
+          run_locally do
+            KAMAL.with_verbosity(:debug) { execute *KAMAL.hook.run(hook, **details, **extra_details) }
+          rescue SSHKit::Command::Failed
+            raise HookError.new("Hook `#{hook}` failed")
+          end
+        end
+      end
+
+      def command
+        @kamal_command ||= begin
+          invocation_class, invocation_commands = *first_invocation
+          if invocation_class == Kamal::Cli::Main
+            invocation_commands[0]
+          else
+            Kamal::Cli::Main.subcommand_classes.find { |command, clazz| clazz == invocation_class }[0]
+          end
+        end
+      end
+
+      def subcommand
+        @kamal_subcommand ||= begin
+          invocation_class, invocation_commands = *first_invocation
+          invocation_commands[0] if invocation_class != Kamal::Cli::Main
+        end
+      end
+
+      def first_invocation
+        instance_variable_get("@_invocations").first
+      end
+
+      def ensure_run_directory
+        on(KAMAL.hosts) do
+          execute(*KAMAL.server.ensure_run_directory)
+        end
+      end
+  end
+end

lib/kamal/cli/build.rb

@@ -0,0 +1,123 @@
+require "uri"
+
+class Kamal::Cli::Build < Kamal::Cli::Base
+  class BuildError < StandardError; end
+
+  desc "deliver", "Build app and push app image to registry then pull image on servers"
+  def deliver
+    mutating do
+      push
+      pull
+    end
+  end
+
+  desc "push", "Build and push app image to registry"
+  def push
+    mutating do
+      cli = self
+
+      verify_local_dependencies
+      run_hook "pre-build"
+
+      if (uncommitted_changes = Kamal::Git.uncommitted_changes).present?
+        say "The following paths have uncommitted changes:\n #{uncommitted_changes}", :yellow
+      end
+
+      run_locally do
+        begin
+          KAMAL.with_verbosity(:debug) do
+            execute *KAMAL.builder.push
+          end
+        rescue SSHKit::Command::Failed => e
+          if e.message =~ /(no builder)|(no such file or directory)/
+            error "Missing compatible builder, so creating a new one first"
+
+            if cli.create
+              KAMAL.with_verbosity(:debug) { execute *KAMAL.builder.push }
+            end
+          else
+            raise
+          end
+        end
+      end
+    end
+  end
+
+  desc "pull", "Pull app image from registry onto servers"
+  def pull
+    mutating do
+      on(KAMAL.hosts) do
+        execute *KAMAL.auditor.record("Pulled image with version #{KAMAL.config.version}"), verbosity: :debug
+        execute *KAMAL.builder.clean, raise_on_non_zero_exit: false
+        execute *KAMAL.builder.pull
+        execute *KAMAL.builder.validate_image
+      end
+    end
+  end
+
+  desc "create", "Create a build setup"
+  def create
+    mutating do
+      if (remote_host = KAMAL.config.builder.remote_host)
+        connect_to_remote_host(remote_host)
+      end
+
+      run_locally do
+        begin
+          debug "Using builder: #{KAMAL.builder.name}"
+          execute *KAMAL.builder.create
+        rescue SSHKit::Command::Failed => e
+          if e.message =~ /stderr=(.*)/
+            error "Couldn't create remote builder: #{$1}"
+            false
+          else
+            raise
+          end
+        end
+      end
+    end
+  end
+
+  desc "remove", "Remove build setup"
+  def remove
+    mutating do
+      run_locally do
+        debug "Using builder: #{KAMAL.builder.name}"
+        execute *KAMAL.builder.remove
+      end
+    end
+  end
+
+  desc "details", "Show build setup"
+  def details
+    run_locally do
+      puts "Builder: #{KAMAL.builder.name}"
+      puts capture(*KAMAL.builder.info)
+    end
+  end
+
+  private
+    def verify_local_dependencies
+      run_locally do
+        begin
+          execute *KAMAL.builder.ensure_local_dependencies_installed
+        rescue SSHKit::Command::Failed => e
+          build_error = e.message =~ /command not found/ ?
+            "Docker is not installed locally" :
+            "Docker buildx plugin is not installed locally"
+
+          raise BuildError, build_error
+        end
+      end
+    end
+
+    def connect_to_remote_host(remote_host)
+      remote_uri = URI.parse(remote_host)
+      if remote_uri.scheme == "ssh"
+        options = { user: remote_uri.user, port: remote_uri.port }.compact
+        on(remote_uri.host, options) do
+          execute "true"
+        end
+      end
+    end
+end

lib/kamal/cli/env.rb

@@ -0,0 +1,54 @@
+require "tempfile"
+
+class Kamal::Cli::Env < Kamal::Cli::Base
+  desc "push", "Push the env file to the remote hosts"
+  def push
+    mutating do
+      on(KAMAL.hosts) do
+        execute *KAMAL.auditor.record("Pushed env files"), verbosity: :debug
+
+        KAMAL.roles_on(host).each do |role|
+          execute *KAMAL.app(role: role).make_env_directory
+          upload! role.env.secrets_io, role.env.secrets_file, mode: 400
+        end
+      end
+
+      on(KAMAL.traefik_hosts) do
+        execute *KAMAL.traefik.make_env_directory
+        upload! KAMAL.traefik.env.secrets_io, KAMAL.traefik.env.secrets_file, mode: 400
+      end
+
+      on(KAMAL.accessory_hosts) do
+        KAMAL.accessories_on(host).each do |accessory|
+          accessory_config = KAMAL.config.accessory(accessory)
+          execute *KAMAL.accessory(accessory).make_env_directory
+          upload! accessory_config.env.secrets_io, accessory_config.env.secrets_file, mode: 400
+        end
+      end
+    end
+  end
+
+  desc "delete", "Delete the env file from the remote hosts"
+  def delete
+    mutating do
+      on(KAMAL.hosts) do
+        execute *KAMAL.auditor.record("Deleted env files"), verbosity: :debug
+
+        KAMAL.roles_on(host).each do |role|
+          execute *KAMAL.app(role: role).remove_env_file
+        end
+      end
+
+      on(KAMAL.traefik_hosts) do
+        execute *KAMAL.traefik.remove_env_file
+      end
+
+      on(KAMAL.accessory_hosts) do
+        KAMAL.accessories_on(host).each do |accessory|
+          accessory_config = KAMAL.config.accessory(accessory)
+          execute *KAMAL.accessory(accessory).remove_env_file
+        end
+      end
+    end
+  end
+end

lib/kamal/cli/healthcheck.rb

@@ -0,0 +1,21 @@
+class Kamal::Cli::Healthcheck < Kamal::Cli::Base
+  default_command :perform
+
+  desc "perform", "Health check current app version"
+  def perform
+    raise "The primary host is not configured to run Traefik" unless KAMAL.config.role(KAMAL.config.primary_role).running_traefik?
+    on(KAMAL.primary_host) do
+      begin
+        execute *KAMAL.healthcheck.run
+        Poller.wait_for_healthy { capture_with_info(*KAMAL.healthcheck.status) }
+      rescue Poller::HealthcheckError => e
+        error capture_with_info(*KAMAL.healthcheck.logs)
+        error capture_with_pretty_json(*KAMAL.healthcheck.container_health_log)
+        raise
+      ensure
+        execute *KAMAL.healthcheck.stop, raise_on_non_zero_exit: false
+        execute *KAMAL.healthcheck.remove, raise_on_non_zero_exit: false
+      end
+    end
+  end
+end

lib/kamal/cli/healthcheck/poller.rb

@@ -0,0 +1,64 @@
+module Kamal::Cli::Healthcheck::Poller
+  extend self
+
+  TRAEFIK_UPDATE_DELAY = 5
+
+  class HealthcheckError < StandardError; end
+
+  def wait_for_healthy(pause_after_ready: false, &block)
+    attempt = 1
+    max_attempts = KAMAL.config.healthcheck["max_attempts"]
+
+    begin
+      case status = block.call
+      when "healthy"
+        sleep TRAEFIK_UPDATE_DELAY if pause_after_ready
+      when "running" # No health check configured
+        sleep KAMAL.config.readiness_delay if pause_after_ready
+      else
+        raise HealthcheckError, "container not ready (#{status})"
+      end
+    rescue HealthcheckError => e
+      if attempt <= max_attempts
+        info "#{e.message}, retrying in #{attempt}s (attempt #{attempt}/#{max_attempts})..."
+        sleep attempt
+        attempt += 1
+        retry
+      else
+        raise
+      end
+    end
+
+    info "Container is healthy!"
+  end
+
+  def wait_for_unhealthy(pause_after_ready: false, &block)
+    attempt = 1
+    max_attempts = KAMAL.config.healthcheck["max_attempts"]
+
+    begin
+      case status = block.call
+      when "unhealthy"
+        sleep TRAEFIK_UPDATE_DELAY if pause_after_ready
+      else
+        raise HealthcheckError, "container not unhealthy (#{status})"
+      end
+    rescue HealthcheckError => e
+      if attempt <= max_attempts
+        info "#{e.message}, retrying in #{attempt}s (attempt #{attempt}/#{max_attempts})..."
+        sleep attempt
+        attempt += 1
+        retry
+      else
+        raise
+      end
+    end
+
+    info "Container is unhealthy!"
+  end
+
+  private
+    def info(message)
+      SSHKit.config.output.info(message)
+    end
+end

lib/kamal/cli/lock.rb

@@ -0,0 +1,46 @@
+class Kamal::Cli::Lock < Kamal::Cli::Base
+  desc "status", "Report lock status"
+  def status
+    handle_missing_lock do
+      on(KAMAL.primary_host) do
+        execute *KAMAL.server.ensure_run_directory
+        puts capture_with_debug(*KAMAL.lock.status)
+      end
+    end
+  end
+
+  desc "acquire", "Acquire the deploy lock"
+  option :message, aliases: "-m", type: :string, desc: "A lock message", required: true
+  def acquire
+    message = options[:message]
+    raise_if_locked do
+      on(KAMAL.primary_host) do
+        execute *KAMAL.server.ensure_run_directory
+        execute *KAMAL.lock.acquire(message, KAMAL.config.version), verbosity: :debug
+      end
+      say "Acquired the deploy lock"
+    end
+  end
+
+  desc "release", "Release the deploy lock"
+  def release
+    handle_missing_lock do
+      on(KAMAL.primary_host) do
+        execute *KAMAL.server.ensure_run_directory
+        execute *KAMAL.lock.release, verbosity: :debug
+      end
+      say "Released the deploy lock"
+    end
+  end
+
+  private
+    def handle_missing_lock
+      yield
+    rescue SSHKit::Runner::ExecuteError => e
+      if e.message =~ /No such file or directory/
+        say "There is no deploy lock"
+      else
+        raise
+      end
+    end
+end

lib/kamal/cli/main.rb

@@ -0,0 +1,268 @@
+class Kamal::Cli::Main < Kamal::Cli::Base
+  desc "setup", "Setup all accessories, push the env, and deploy app to servers"
+  option :skip_push, aliases: "-P", type: :boolean, default: false, desc: "Skip image build and push"
+  def setup
+    print_runtime do
+      mutating do
+        invoke_options = deploy_options
+
+        say "Ensure Docker is installed...", :magenta
+        invoke "kamal:cli:server:bootstrap", [], invoke_options
+
+        say "Push env files...", :magenta
+        invoke "kamal:cli:env:push", [], invoke_options
+
+        invoke "kamal:cli:accessory:boot", [ "all" ], invoke_options
+        deploy
+      end
+    end
+  end
+
+  desc "deploy", "Deploy app to servers"
+  option :skip_push, aliases: "-P", type: :boolean, default: false, desc: "Skip image build and push"
+  def deploy
+    runtime = print_runtime do
+      mutating do
+        invoke_options = deploy_options
+
+        say "Log into image registry...", :magenta
+        invoke "kamal:cli:registry:login", [], invoke_options
+
+        if options[:skip_push]
+          say "Pull app image...", :magenta
+          invoke "kamal:cli:build:pull", [], invoke_options
+        else
+          say "Build and push app image...", :magenta
+          invoke "kamal:cli:build:deliver", [], invoke_options
+        end
+
+        run_hook "pre-deploy"
+
+        say "Ensure Traefik is running...", :magenta
+        invoke "kamal:cli:traefik:boot", [], invoke_options
+
+        if KAMAL.config.role(KAMAL.config.primary_role).running_traefik?
+          say "Ensure app can pass healthcheck...", :magenta
+          invoke "kamal:cli:healthcheck:perform", [], invoke_options
+        end
+
+        say "Detect stale containers...", :magenta
+        invoke "kamal:cli:app:stale_containers", [], invoke_options.merge(stop: true)
+
+        invoke "kamal:cli:app:boot", [], invoke_options
+
+        say "Prune old containers and images...", :magenta
+        invoke "kamal:cli:prune:all", [], invoke_options
+      end
+    end
+
+    run_hook "post-deploy", runtime: runtime.round
+  end
+
+  desc "redeploy", "Deploy app to servers without bootstrapping servers, starting Traefik, pruning, and registry login"
+  option :skip_push, aliases: "-P", type: :boolean, default: false, desc: "Skip image build and push"
+  def redeploy
+    runtime = print_runtime do
+      mutating do
+        invoke_options = deploy_options
+
+        if options[:skip_push]
+          say "Pull app image...", :magenta
+          invoke "kamal:cli:build:pull", [], invoke_options
+        else
+          say "Build and push app image...", :magenta
+          invoke "kamal:cli:build:deliver", [], invoke_options
+        end
+
+        run_hook "pre-deploy"
+
+        say "Ensure app can pass healthcheck...", :magenta
+        invoke "kamal:cli:healthcheck:perform", [], invoke_options
+
+        say "Detect stale containers...", :magenta
+        invoke "kamal:cli:app:stale_containers", [], invoke_options.merge(stop: true)
+
+        invoke "kamal:cli:app:boot", [], invoke_options
+      end
+    end
+
+    run_hook "post-deploy", runtime: runtime.round
+  end
+
+  desc "rollback [VERSION]", "Rollback app to VERSION"
+  def rollback(version)
+    rolled_back = false
+    runtime = print_runtime do
+      mutating do
+        invoke_options = deploy_options
+
+        KAMAL.config.version = version
+        old_version = nil
+
+        if container_available?(version)
+          run_hook "pre-deploy"
+
+          invoke "kamal:cli:app:boot", [], invoke_options.merge(version: version)
+          rolled_back = true
+        else
+          say "The app version '#{version}' is not available as a container (use 'kamal app containers' for available versions)", :red
+        end
+      end
+    end
+
+    run_hook "post-deploy", runtime: runtime.round if rolled_back
+  end
+
+  desc "details", "Show details about all containers"
+  def details
+    invoke "kamal:cli:traefik:details"
+    invoke "kamal:cli:app:details"
+    invoke "kamal:cli:accessory:details", [ "all" ]
+  end
+
+  desc "audit", "Show audit log from servers"
+  def audit
+    on(KAMAL.hosts) do |host|
+      puts_by_host host, capture_with_info(*KAMAL.auditor.reveal)
+    end
+  end
+
+  desc "config", "Show combined config (including secrets!)"
+  def config
+    run_locally do
+      puts Kamal::Utils.redacted(KAMAL.config.to_h).to_yaml
+    end
+  end
+
+  desc "init", "Create config stub in config/deploy.yml and env stub in .env"
+  option :bundle, type: :boolean, default: false, desc: "Add Kamal to the Gemfile and create a bin/kamal binstub"
+  def init
+    require "fileutils"
+
+    if (deploy_file = Pathname.new(File.expand_path("config/deploy.yml"))).exist?
+      puts "Config file already exists in config/deploy.yml (remove first to create a new one)"
+    else
+      FileUtils.mkdir_p deploy_file.dirname
+      FileUtils.cp_r Pathname.new(File.expand_path("templates/deploy.yml", __dir__)), deploy_file
+      puts "Created configuration file in config/deploy.yml"
+    end
+
+    unless (deploy_file = Pathname.new(File.expand_path(".env"))).exist?
+      FileUtils.cp_r Pathname.new(File.expand_path("templates/template.env", __dir__)), deploy_file
+      puts "Created .env file"
+    end
+
+    unless (hooks_dir = Pathname.new(File.expand_path(".kamal/hooks"))).exist?
+      hooks_dir.mkpath
+      Pathname.new(File.expand_path("templates/sample_hooks", __dir__)).each_child do |sample_hook|
+        FileUtils.cp sample_hook, hooks_dir, preserve: true
+      end
+      puts "Created sample hooks in .kamal/hooks"
+    end
+
+    if options[:bundle]
+      if (binstub = Pathname.new(File.expand_path("bin/kamal"))).exist?
+        puts "Binstub already exists in bin/kamal (remove first to create a new one)"
+      else
+        puts "Adding Kamal to Gemfile and bundle..."
+        run_locally do
+          execute :bundle, :add, :kamal
+          execute :bundle, :binstubs, :kamal
+        end
+        puts "Created binstub file in bin/kamal"
+      end
+    end
+  end
+
+  desc "envify", "Create .env by evaluating .env.erb (or .env.staging.erb -> .env.staging when using -d staging)"
+  option :skip_push, aliases: "-P", type: :boolean, default: false, desc: "Skip .env file push"
+  def envify
+    if destination = options[:destination]
+      env_template_path = ".env.#{destination}.erb"
+      env_path          = ".env.#{destination}"
+    else
+      env_template_path = ".env.erb"
+      env_path          = ".env"
+    end
+
+    File.write(env_path, ERB.new(File.read(env_template_path), trim_mode: "-").result, perm: 0600)
+
+    unless options[:skip_push]
+      reload_envs
+      invoke "kamal:cli:env:push", options
+    end
+  end
+
+  desc "remove", "Remove Traefik, app, accessories, and registry session from servers"
+  option :confirmed, aliases: "-y", type: :boolean, default: false, desc: "Proceed without confirmation question"
+  def remove
+    mutating do
+      confirming "This will remove all containers and images. Are you sure?" do
+        invoke "kamal:cli:traefik:remove", [], options.without(:confirmed)
+        invoke "kamal:cli:app:remove", [], options.without(:confirmed)
+        invoke "kamal:cli:accessory:remove", [ "all" ], options
+        invoke "kamal:cli:registry:logout", [], options.without(:confirmed)
+      end
+    end
+  end
+
+  desc "version", "Show Kamal version"
+  def version
+    puts Kamal::VERSION
+  end
+
+  desc "accessory", "Manage accessories (db/redis/search)"
+  subcommand "accessory", Kamal::Cli::Accessory
+
+  desc "app", "Manage application"
+  subcommand "app", Kamal::Cli::App
+
+  desc "build", "Build application image"
+  subcommand "build", Kamal::Cli::Build
+
+  desc "env", "Manage environment files"
+  subcommand "env", Kamal::Cli::Env
+
+  desc "healthcheck", "Healthcheck application"
+  subcommand "healthcheck", Kamal::Cli::Healthcheck
+
+  desc "lock", "Manage the deploy lock"
+  subcommand "lock", Kamal::Cli::Lock
+
+  desc "prune", "Prune old application images and containers"
+  subcommand "prune", Kamal::Cli::Prune
+
+  desc "registry", "Login and -out of the image registry"
+  subcommand "registry", Kamal::Cli::Registry
+
+  desc "server", "Bootstrap servers with curl and Docker"
+  subcommand "server", Kamal::Cli::Server
+
+  desc "traefik", "Manage Traefik load balancer"
+  subcommand "traefik", Kamal::Cli::Traefik
+
+  private
+    def container_available?(version)
+      begin
+        on(KAMAL.hosts) do
+          KAMAL.roles_on(host).each do |role|
+            container_id = capture_with_info(*KAMAL.app(role: role).container_id_for_version(version))
+            raise "Container not found" unless container_id.present?
+          end
+        end
+      rescue SSHKit::Runner::ExecuteError => e
+        if e.message =~ /Container not found/
+          say "Error looking for container version #{version}: #{e.message}"
+          return false
+        else
+          raise
+        end
+      end
+
+      true
+    end
+
+    def deploy_options
+      { "version" => KAMAL.config.version }.merge(options.without("skip_push"))
+    end
+end

lib/kamal/cli/prune.rb

@@ -0,0 +1,35 @@
+class Kamal::Cli::Prune < Kamal::Cli::Base
+  desc "all", "Prune unused images and stopped containers"
+  def all
+    mutating do
+      containers
+      images
+    end
+  end
+
+  desc "images", "Prune unused images"
+  def images
+    mutating do
+      on(KAMAL.hosts) do
+        execute *KAMAL.auditor.record("Pruned images"), verbosity: :debug
+        execute *KAMAL.prune.dangling_images
+        execute *KAMAL.prune.tagged_images
+      end
+    end
+  end
+
+  desc "containers", "Prune all stopped containers, except the last n (default 5)"
+  option :retain, type: :numeric, default: nil, desc: "Number of containers to retain"
+  def containers
+    retain = options.fetch(:retain, KAMAL.config.retain_containers)
+    raise "retain must be at least 1" if retain < 1
+
+    mutating do
+      on(KAMAL.hosts) do
+        execute *KAMAL.auditor.record("Pruned containers"), verbosity: :debug
+        execute *KAMAL.prune.app_containers(retain: retain)
+        execute *KAMAL.prune.healthcheck_containers
+      end
+    end
+  end
+end

lib/kamal/cli/registry.rb

@@ -0,0 +1,18 @@
+class Kamal::Cli::Registry < Kamal::Cli::Base
+  desc "login", "Log in to registry locally and remotely"
+  def login
+    run_locally    { execute *KAMAL.registry.login }
+    on(KAMAL.hosts) { execute *KAMAL.registry.login }
+  # FIXME: This rescue needed?
+  rescue ArgumentError => e
+    puts e.message
+  end
+
+  desc "logout", "Log out of registry remotely"
+  def logout
+    on(KAMAL.hosts) { execute *KAMAL.registry.logout }
+  # FIXME: This rescue needed?
+  rescue ArgumentError => e
+    puts e.message
+  end
+end

lib/kamal/cli/server.rb

@@ -0,0 +1,25 @@
+class Kamal::Cli::Server < Kamal::Cli::Base
+  desc "bootstrap", "Set up Docker to run Kamal apps"
+  def bootstrap
+    missing = []
+
+    on(KAMAL.hosts | KAMAL.accessory_hosts) do |host|
+      unless execute(*KAMAL.docker.installed?, raise_on_non_zero_exit: false)
+        if execute(*KAMAL.docker.superuser?, raise_on_non_zero_exit: false)
+          info "Missing Docker on #{host}. Installing…"
+          execute *KAMAL.docker.install
+        else
+          missing << host
+        end
+      end
+
+      execute(*KAMAL.server.ensure_run_directory)
+    end
+
+    if missing.any?
+      raise "Docker is not installed on #{missing.join(", ")} and can't be automatically installed without having root access and either `wget` or `curl`. Install Docker manually: https://docs.docker.com/engine/install/"
+    end
+
+    run_hook "docker-setup"
+  end
+end

lib/kamal/cli/templates/deploy.yml

@@ -0,0 +1,101 @@
+# Name of your application. Used to uniquely configure containers.
+service: my-app
+
+# Name of the container image.
+image: user/my-app
+
+# Deploy to these servers.
+servers:
+  - 192.168.0.1
+
+# Credentials for your image host.
+registry:
+  # Specify the registry server, if you're not using Docker Hub
+  # server: registry.digitalocean.com / ghcr.io / ...
+  username: my-user
+
+  # Always use an access token rather than real password when possible.
+  password:
+    - KAMAL_REGISTRY_PASSWORD
+
+# Inject ENV variables into containers (secrets come from .env).
+# Remember to run `kamal env push` after making changes!
+# env:
+#   clear:
+#     DB_HOST: 192.168.0.2
+#   secret:
+#     - RAILS_MASTER_KEY
+
+# Use a different ssh user than root
+# ssh:
+#   user: app
+
+# Configure builder setup.
+# builder:
+#   args:
+#     RUBY_VERSION: 3.2.0
+#   secrets:
+#     - GITHUB_TOKEN
+#   remote:
+#     arch: amd64
+#     host: ssh://app@192.168.0.1
+
+# Use accessory services (secrets come from .env).
+# accessories:
+#   db:
+#     image: mysql:8.0
+#     host: 192.168.0.2
+#     port: 3306
+#     env:
+#       clear:
+#         MYSQL_ROOT_HOST: '%'
+#       secret:
+#         - MYSQL_ROOT_PASSWORD
+#     files:
+#       - config/mysql/production.cnf:/etc/mysql/my.cnf
+#       - db/production.sql:/docker-entrypoint-initdb.d/setup.sql
+#     directories:
+#       - data:/var/lib/mysql
+#   redis:
+#     image: redis:7.0
+#     host: 192.168.0.2
+#     port: 6379
+#     directories:
+#       - data:/data
+
+# Configure custom arguments for Traefik
+# traefik:
+#   args:
+#     accesslog: true
+#     accesslog.format: json
+
+# Configure a custom healthcheck (default is /up on port 3000)
+# healthcheck:
+#   path: /healthz
+#   port: 4000
+
+# Bridge fingerprinted assets, like JS and CSS, between versions to avoid
+# hitting 404 on in-flight requests. Combines all files from new and old
+# version inside the asset_path.
+#
+# If your app is using the Sprockets gem, ensure it sets `config.assets.manifest`.
+# See https://github.com/basecamp/kamal/issues/626 for details
+#
+# asset_path: /rails/public/assets
+
+# Configure rolling deploys by setting a wait time between batches of restarts.
+# boot:
+#   limit: 10 # Can also specify as a percentage of total hosts, such as "25%"
+#   wait: 2
+
+# Configure the role used to determine the primary_host. This host takes
+# deploy locks, runs health checks during the deploy, and follow logs, etc.
+#
+# Caution: there's no support for role renaming yet, so be careful to cleanup
+#          the previous role on the deployed hosts.
+# primary_role: web
+
+# Controls if we abort when see a role with no hosts. Disabling this may be
+# useful for more complex deploy configurations.
+#
+# allow_empty_roles: false

lib/kamal/cli/templates/sample_hooks/docker-setup.sample

@@ -0,0 +1,7 @@
+#!/usr/bin/env ruby
+
+# A sample docker-setup hook
+#
+# Sets up a Docker network which can then be used by the application’s containers
+
+ssh user@example.com docker network create kamal

lib/kamal/cli/templates/sample_hooks/post-deploy.sample

@@ -0,0 +1,14 @@
+#!/bin/sh
+
+# A sample post-deploy hook
+#
+# These environment variables are available:
+# KAMAL_RECORDED_AT
+# KAMAL_PERFORMER
+# KAMAL_VERSION
+# KAMAL_HOSTS
+# KAMAL_ROLE (if set)
+# KAMAL_DESTINATION (if set)
+# KAMAL_RUNTIME
+
+echo "$KAMAL_PERFORMER deployed $KAMAL_VERSION to $KAMAL_DESTINATION in $KAMAL_RUNTIME seconds"

lib/kamal/cli/templates/sample_hooks/post-traefik-reboot.sample

@@ -0,0 +1,3 @@
+#!/bin/sh
+
+echo "Rebooted Traefik on $KAMAL_HOSTS"

lib/kamal/cli/templates/sample_hooks/pre-build.sample

@@ -0,0 +1,51 @@
+#!/bin/sh
+
+# A sample pre-build hook
+#
+# Checks:
+# 1. We have a clean checkout
+# 2. A remote is configured
+# 3. The branch has been pushed to the remote
+# 4. The version we are deploying matches the remote
+#
+# These environment variables are available:
+# KAMAL_RECORDED_AT
+# KAMAL_PERFORMER
+# KAMAL_VERSION
+# KAMAL_HOSTS
+# KAMAL_ROLE (if set)
+# KAMAL_DESTINATION (if set)
+
+if [ -n "$(git status --porcelain)" ]; then
+  echo "Git checkout is not clean, aborting..." >&2
+  git status --porcelain >&2
+  exit 1
+fi
+
+first_remote=$(git remote)
+
+if [ -z "$first_remote" ]; then
+  echo "No git remote set, aborting..." >&2
+  exit 1
+fi
+
+current_branch=$(git branch --show-current)
+
+if [ -z "$current_branch" ]; then
+  echo "Not on a git branch, aborting..." >&2
+  exit 1
+fi
+
+remote_head=$(git ls-remote $first_remote --tags $current_branch | cut -f1)
+
+if [ -z "$remote_head" ]; then
+  echo "Branch not pushed to remote, aborting..." >&2
+  exit 1
+fi
+
+if [ "$KAMAL_VERSION" != "$remote_head" ]; then
+  echo "Version ($KAMAL_VERSION) does not match remote HEAD ($remote_head), aborting..." >&2
+  exit 1
+fi
+
+exit 0

lib/kamal/cli/templates/sample_hooks/pre-connect.sample

@@ -0,0 +1,47 @@
+#!/usr/bin/env ruby
+
+# A sample pre-connect check
+#
+# Warms DNS before connecting to hosts in parallel
+#
+# These environment variables are available:
+# KAMAL_RECORDED_AT
+# KAMAL_PERFORMER
+# KAMAL_VERSION
+# KAMAL_HOSTS
+# KAMAL_ROLE (if set)
+# KAMAL_DESTINATION (if set)
+# KAMAL_RUNTIME
+
+hosts = ENV["KAMAL_HOSTS"].split(",")
+results = nil
+max = 3
+
+elapsed = Benchmark.realtime do
+  results = hosts.map do |host|
+    Thread.new do
+      tries = 1
+
+      begin
+        Socket.getaddrinfo(host, 0, Socket::AF_UNSPEC, Socket::SOCK_STREAM, nil, Socket::AI_CANONNAME)
+      rescue SocketError
+        if tries < max
+          puts "Retrying DNS warmup: #{host}"
+          tries += 1
+          sleep rand
+          retry
+        else
+          puts "DNS warmup failed: #{host}"
+          host
+        end
+      end
+
+      tries
+    end
+  end.map(&:value)
+end
+
+retries = results.sum - hosts.size
+nopes = results.count { |r| r == max }
+
+puts "Prewarmed %d DNS lookups in %.2f sec: %d retries, %d failures" % [ hosts.size, elapsed, retries, nopes ]

lib/kamal/cli/templates/sample_hooks/pre-deploy.sample

@@ -0,0 +1,109 @@
+#!/usr/bin/env ruby
+
+# A sample pre-deploy hook
+#
+# Checks the Github status of the build, waiting for a pending build to complete for up to 720 seconds.
+#
+# Fails unless the combined status is "success"
+#
+# These environment variables are available:
+# KAMAL_RECORDED_AT
+# KAMAL_PERFORMER
+# KAMAL_VERSION
+# KAMAL_HOSTS
+# KAMAL_COMMAND
+# KAMAL_SUBCOMMAND
+# KAMAL_ROLE (if set)
+# KAMAL_DESTINATION (if set)
+
+# Only check the build status for production deployments
+if ENV["KAMAL_COMMAND"] == "rollback" || ENV["KAMAL_DESTINATION"] != "production"
+  exit 0
+end
+
+require "bundler/inline"
+
+# true = install gems so this is fast on repeat invocations
+gemfile(true, quiet: true) do
+  source "https://rubygems.org"
+
+  gem "octokit"
+  gem "faraday-retry"
+end
+
+MAX_ATTEMPTS = 72
+ATTEMPTS_GAP = 10
+
+def exit_with_error(message)
+  $stderr.puts message
+  exit 1
+end
+
+class GithubStatusChecks
+  attr_reader :remote_url, :git_sha, :github_client, :combined_status
+
+  def initialize
+    @remote_url = `git config --get remote.origin.url`.strip.delete_prefix("https://github.com/")
+    @git_sha = `git rev-parse HEAD`.strip
+    @github_client = Octokit::Client.new(access_token: ENV["GITHUB_TOKEN"])
+    refresh!
+  end
+
+  def refresh!
+    @combined_status = github_client.combined_status(remote_url, git_sha)
+  end
+
+  def state
+    combined_status[:state]
+  end
+
+  def first_status_url
+    first_status = combined_status[:statuses].find { |status| status[:state] == state }
+    first_status && first_status[:target_url]
+  end
+
+  def complete_count
+    combined_status[:statuses].count { |status| status[:state] != "pending"}
+  end
+
+  def total_count
+    combined_status[:statuses].count
+  end
+
+  def current_status
+    if total_count > 0
+      "Completed #{complete_count}/#{total_count} checks, see #{first_status_url} ..."
+    else
+      "Build not started..."
+    end
+  end
+end
+
+
+$stdout.sync = true
+
+puts "Checking build status..."
+attempts = 0
+checks = GithubStatusChecks.new
+
+begin
+  loop do
+    case checks.state
+    when "success"
+      puts "Checks passed, see #{checks.first_status_url}"
+      exit 0
+    when "failure"
+      exit_with_error "Checks failed, see #{checks.first_status_url}"
+    when "pending"
+      attempts += 1
+    end
+
+    exit_with_error "Checks are still pending, gave up after #{MAX_ATTEMPTS * ATTEMPTS_GAP} seconds" if attempts == MAX_ATTEMPTS
+
+    puts checks.current_status
+    sleep(ATTEMPTS_GAP)
+    checks.refresh!
+  end
+rescue Octokit::NotFound
+  exit_with_error "Build status could not be found"
+end

lib/kamal/cli/templates/sample_hooks/pre-traefik-reboot.sample

@@ -0,0 +1,3 @@
+#!/bin/sh
+
+echo "Rebooting Traefik on $KAMAL_HOSTS..."

lib/kamal/cli/templates/template.env

@@ -0,0 +1,2 @@
+KAMAL_REGISTRY_PASSWORD=change-this
+RAILS_MASTER_KEY=another-env

lib/kamal/cli/traefik.rb

@@ -0,0 +1,120 @@
+class Kamal::Cli::Traefik < Kamal::Cli::Base
+  desc "boot", "Boot Traefik on servers"
+  def boot
+    mutating do
+      on(KAMAL.traefik_hosts) do
+        execute *KAMAL.registry.login
+        execute *KAMAL.traefik.start_or_run
+      end
+    end
+  end
+
+  desc "reboot", "Reboot Traefik on servers (stop container, remove container, start new container)"
+  option :rolling, type: :boolean, default: false, desc: "Reboot traefik on hosts in sequence, rather than in parallel"
+  option :confirmed, aliases: "-y", type: :boolean, default: false, desc: "Proceed without confirmation question"
+  def reboot
+    confirming "This will cause a brief outage on each host. Are you sure?" do
+      mutating do
+        host_groups = options[:rolling] ? KAMAL.traefik_hosts : [ KAMAL.traefik_hosts ]
+        host_groups.each do |hosts|
+          host_list = Array(hosts).join(",")
+          run_hook "pre-traefik-reboot", hosts: host_list
+          on(hosts) do
+            execute *KAMAL.auditor.record("Rebooted traefik"), verbosity: :debug
+            execute *KAMAL.registry.login
+            execute *KAMAL.traefik.stop, raise_on_non_zero_exit: false
+            execute *KAMAL.traefik.remove_container
+            execute *KAMAL.traefik.run
+          end
+          run_hook "post-traefik-reboot", hosts: host_list
+        end
+      end
+    end
+  end
+
+  desc "start", "Start existing Traefik container on servers"
+  def start
+    mutating do
+      on(KAMAL.traefik_hosts) do
+        execute *KAMAL.auditor.record("Started traefik"), verbosity: :debug
+        execute *KAMAL.traefik.start
+      end
+    end
+  end
+
+  desc "stop", "Stop existing Traefik container on servers"
+  def stop
+    mutating do
+      on(KAMAL.traefik_hosts) do
+        execute *KAMAL.auditor.record("Stopped traefik"), verbosity: :debug
+        execute *KAMAL.traefik.stop, raise_on_non_zero_exit: false
+      end
+    end
+  end
+
+  desc "restart", "Restart existing Traefik container on servers"
+  def restart
+    mutating do
+      stop
+      start
+    end
+  end
+
+  desc "details", "Show details about Traefik container from servers"
+  def details
+    on(KAMAL.traefik_hosts) { |host| puts_by_host host, capture_with_info(*KAMAL.traefik.info), type: "Traefik" }
+  end
+
+  desc "logs", "Show log lines from Traefik on servers"
+  option :since, aliases: "-s", desc: "Show logs since timestamp (e.g. 2013-01-02T13:23:37Z) or relative (e.g. 42m for 42 minutes)"
+  option :lines, type: :numeric, aliases: "-n", desc: "Number of log lines to pull from each server"
+  option :grep, aliases: "-g", desc: "Show lines with grep match only (use this to fetch specific requests by id)"
+  option :follow, aliases: "-f", desc: "Follow logs on primary server (or specific host set by --hosts)"
+  def logs
+    grep = options[:grep]
+
+    if options[:follow]
+      run_locally do
+        info "Following logs on #{KAMAL.primary_host}..."
+        info KAMAL.traefik.follow_logs(host: KAMAL.primary_host, grep: grep)
+        exec KAMAL.traefik.follow_logs(host: KAMAL.primary_host, grep: grep)
+      end
+    else
+      since = options[:since]
+      lines = options[:lines].presence || ((since || grep) ? nil : 100) # Default to 100 lines if since or grep isn't set
+
+      on(KAMAL.traefik_hosts) do |host|
+        puts_by_host host, capture(*KAMAL.traefik.logs(since: since, lines: lines, grep: grep)), type: "Traefik"
+      end
+    end
+  end
+
+  desc "remove", "Remove Traefik container and image from servers"
+  def remove
+    mutating do
+      stop
+      remove_container
+      remove_image
+    end
+  end
+
+  desc "remove_container", "Remove Traefik container from servers", hide: true
+  def remove_container
+    mutating do
+      on(KAMAL.traefik_hosts) do
+        execute *KAMAL.auditor.record("Removed traefik container"), verbosity: :debug
+        execute *KAMAL.traefik.remove_container
+      end
+    end
+  end
+
+  desc "remove_image", "Remove Traefik image from servers", hide: true
+  def remove_image
+    mutating do
+      on(KAMAL.traefik_hosts) do
+        execute *KAMAL.auditor.record("Removed traefik image"), verbosity: :debug
+        execute *KAMAL.traefik.remove_image
+      end
+    end
+  end
+end

lib/kamal/commander.rb

@@ -0,0 +1,184 @@
+require "active_support/core_ext/enumerable"
+require "active_support/core_ext/module/delegation"
+
+class Kamal::Commander
+  attr_accessor :verbosity, :holding_lock, :hold_lock_on_error
+
+  def initialize
+    self.verbosity = :info
+    self.holding_lock = false
+    self.hold_lock_on_error = false
+  end
+
+  def config
+    @config ||= Kamal::Configuration.create_from(**@config_kwargs).tap do |config|
+      @config_kwargs = nil
+      configure_sshkit_with(config)
+    end
+  end
+
+  def configure(**kwargs)
+    @config, @config_kwargs = nil, kwargs
+  end
+
+  attr_reader :specific_roles, :specific_hosts
+
+  def specific_primary!
+    self.specific_hosts = [ config.primary_host ]
+  end
+
+  def specific_roles=(role_names)
+    if role_names.present?
+      @specific_roles = Kamal::Utils.filter_specific_items(role_names, config.roles)
+
+      if @specific_roles.empty?
+        raise ArgumentError, "No --roles match for #{role_names.join(',')}"
+      end
+
+      @specific_roles
+    end
+  end
+
+  def specific_hosts=(hosts)
+    if hosts.present?
+      @specific_hosts = Kamal::Utils.filter_specific_items(hosts, config.all_hosts)
+
+      if @specific_hosts.empty?
+        raise ArgumentError, "No --hosts match for #{hosts.join(',')}"
+      end
+
+      @specific_hosts
+    end
+  end
+
+  def primary_host
+    # Given a list of specific roles, make an effort to match up with the primary_role
+    specific_hosts&.first || specific_roles&.detect { |role| role == config.primary_role }&.primary_host || specific_roles&.first&.primary_host || config.primary_host
+  end
+
+  def primary_role
+    roles_on(primary_host).first
+  end
+
+  def roles
+    (specific_roles || config.roles).select do |role|
+      ((specific_hosts || config.all_hosts) & role.hosts).any?
+    end
+  end
+
+  def hosts
+    (specific_hosts || config.all_hosts).select do |host|
+      (specific_roles || config.roles).flat_map(&:hosts).include?(host)
+    end
+  end
+
+  def roles_on(host)
+    roles.select { |role| role.hosts.include?(host.to_s) }
+  end
+
+  def traefik_hosts
+    specific_hosts || config.traefik_hosts
+  end
+
+  def accessory_hosts
+    specific_hosts || config.accessories.flat_map(&:hosts)
+  end
+
+  def accessory_names
+    config.accessories&.collect(&:name) || []
+  end
+
+  def accessories_on(host)
+    config.accessories.select { |accessory| accessory.hosts.include?(host.to_s) }.map(&:name)
+  end
+
+
+  def app(role: nil)
+    Kamal::Commands::App.new(config, role: role)
+  end
+
+  def accessory(name)
+    Kamal::Commands::Accessory.new(config, name: name)
+  end
+
+  def auditor(**details)
+    Kamal::Commands::Auditor.new(config, **details)
+  end
+
+  def builder
+    @builder ||= Kamal::Commands::Builder.new(config)
+  end
+
+  def docker
+    @docker ||= Kamal::Commands::Docker.new(config)
+  end
+
+  def healthcheck
+    @healthcheck ||= Kamal::Commands::Healthcheck.new(config)
+  end
+
+  def hook
+    @hook ||= Kamal::Commands::Hook.new(config)
+  end
+
+  def lock
+    @lock ||= Kamal::Commands::Lock.new(config)
+  end
+
+  def prune
+    @prune ||= Kamal::Commands::Prune.new(config)
+  end
+
+  def registry
+    @registry ||= Kamal::Commands::Registry.new(config)
+  end
+
+  def server
+    @server ||= Kamal::Commands::Server.new(config)
+  end
+
+  def traefik
+    @traefik ||= Kamal::Commands::Traefik.new(config)
+  end
+
+
+  def with_verbosity(level)
+    old_level = self.verbosity
+
+    self.verbosity = level
+    SSHKit.config.output_verbosity = level
+
+    yield
+  ensure
+    self.verbosity = old_level
+    SSHKit.config.output_verbosity = old_level
+  end
+
+  def boot_strategy
+    if config.boot.limit.present?
+      { in: :groups, limit: config.boot.limit, wait: config.boot.wait }
+    else
+      {}
+    end
+  end
+
+  def holding_lock?
+    self.holding_lock
+  end
+
+  def hold_lock_on_error?
+    self.hold_lock_on_error
+  end
+
+  private
+    # Lazy setup of SSHKit
+    def configure_sshkit_with(config)
+      SSHKit::Backend::Netssh.pool.idle_timeout = config.sshkit.pool_idle_timeout
+      SSHKit::Backend::Netssh.configure do |sshkit|
+        sshkit.max_concurrent_starts = config.sshkit.max_concurrent_starts
+        sshkit.ssh_options = config.ssh.options
+      end
+      SSHKit.config.command_map[:docker] = "docker" # No need to use /usr/bin/env, just clogs up the logs
+      SSHKit.config.output_verbosity = verbosity
+    end
+end

lib/kamal/commands.rb

@@ -0,0 +1,2 @@
+module Kamal::Commands
+end

lib/kamal/commands/accessory.rb

@@ -0,0 +1,113 @@
+class Kamal::Commands::Accessory < Kamal::Commands::Base
+  attr_reader :accessory_config
+  delegate :service_name, :image, :hosts, :port, :files, :directories, :cmd,
+           :publish_args, :env_args, :volume_args, :label_args, :option_args, to: :accessory_config
+
+  def initialize(config, name:)
+    super(config)
+    @accessory_config = config.accessory(name)
+  end
+
+  def run
+    docker :run,
+      "--name", service_name,
+      "--detach",
+      "--restart", "unless-stopped",
+      *config.logging_args,
+      *publish_args,
+      *env_args,
+      *volume_args,
+      *label_args,
+      *option_args,
+      image,
+      cmd
+  end
+
+  def start
+    docker :container, :start, service_name
+  end
+
+  def stop
+    docker :container, :stop, service_name
+  end
+
+  def info
+    docker :ps, *service_filter
+  end
+
+
+  def logs(since: nil, lines: nil, grep: nil)
+    pipe \
+      docker(:logs, service_name, (" --since #{since}" if since), (" --tail #{lines}" if lines), "--timestamps", "2>&1"),
+      ("grep '#{grep}'" if grep)
+  end
+
+  def follow_logs(grep: nil)
+    run_over_ssh \
+      pipe \
+        docker(:logs, service_name, "--timestamps", "--tail", "10", "--follow", "2>&1"),
+        (%(grep "#{grep}") if grep)
+  end
+
+
+  def execute_in_existing_container(*command, interactive: false)
+    docker :exec,
+      ("-it" if interactive),
+      service_name,
+      *command
+  end
+
+  def execute_in_new_container(*command, interactive: false)
+    docker :run,
+      ("-it" if interactive),
+      "--rm",
+      *env_args,
+      *volume_args,
+      image,
+      *command
+  end
+
+  def execute_in_existing_container_over_ssh(*command)
+    run_over_ssh execute_in_existing_container(*command, interactive: true)
+  end
+
+  def execute_in_new_container_over_ssh(*command)
+    run_over_ssh execute_in_new_container(*command, interactive: true)
+  end
+
+  def run_over_ssh(command)
+    super command, host: hosts.first
+  end
+
+
+  def ensure_local_file_present(local_file)
+    if !local_file.is_a?(StringIO) && !Pathname.new(local_file).exist?
+      raise "Missing file: #{local_file}"
+    end
+  end
+
+  def remove_service_directory
+    [ :rm, "-rf", service_name ]
+  end
+
+  def remove_container
+    docker :container, :prune, "--force", *service_filter
+  end
+
+  def remove_image
+    docker :image, :rm, "--force", image
+  end
+
+  def make_env_directory
+    make_directory accessory_config.env.secrets_directory
+  end
+
+  def remove_env_file
+    [ :rm, "-f", accessory_config.env.secrets_file ]
+  end
+
+  private
+    def service_filter
+      [ "--filter", "label=service=#{service_name}" ]
+    end
+end

lib/kamal/commands/app.rb

@@ -0,0 +1,97 @@
+class Kamal::Commands::App < Kamal::Commands::Base
+  include Assets, Containers, Cord, Execution, Images, Logging
+
+  ACTIVE_DOCKER_STATUSES = [ :running, :restarting ]
+
+  attr_reader :role, :role
+
+  def initialize(config, role: nil)
+    super(config)
+    @role = role
+  end
+
+  def run(hostname: nil)
+    docker :run,
+      "--detach",
+      "--restart unless-stopped",
+      "--name", container_name,
+      *([ "--hostname", hostname ] if hostname),
+      "-e", "KAMAL_CONTAINER_NAME=\"#{container_name}\"",
+      "-e", "KAMAL_VERSION=\"#{config.version}\"",
+      *role.env_args,
+      *role.health_check_args,
+      *role.logging_args,
+      *config.volume_args,
+      *role.asset_volume_args,
+      *role.label_args,
+      *role.option_args,
+      config.absolute_image,
+      role.cmd
+  end
+
+  def start
+    docker :start, container_name
+  end
+
+  def status(version:)
+    pipe container_id_for_version(version), xargs(docker(:inspect, "--format", DOCKER_HEALTH_STATUS_FORMAT))
+  end
+
+  def stop(version: nil)
+    pipe \
+      version ? container_id_for_version(version) : current_running_container_id,
+      xargs(config.stop_wait_time ? docker(:stop, "-t", config.stop_wait_time) : docker(:stop))
+  end
+
+  def info
+    docker :ps, *filter_args
+  end
+
+
+  def current_running_container_id
+    docker :ps, "--quiet", *filter_args(statuses: ACTIVE_DOCKER_STATUSES), "--latest"
+  end
+
+  def container_id_for_version(version, only_running: false)
+    container_id_for(container_name: container_name(version), only_running: only_running)
+  end
+
+  def current_running_version
+    list_versions("--latest", statuses: ACTIVE_DOCKER_STATUSES)
+  end
+
+  def list_versions(*docker_args, statuses: nil)
+    pipe \
+      docker(:ps, *filter_args(statuses: statuses), *docker_args, "--format", '"{{.Names}}"'),
+      %(while read line; do echo ${line##{role.container_prefix}-}; done) # Extract SHA from "service-role-dest-SHA"
+  end
+
+
+  def make_env_directory
+    make_directory role.env.secrets_directory
+  end
+
+  def remove_env_file
+    [ :rm, "-f", role.env.secrets_file ]
+  end
+
+
+  private
+    def container_name(version = nil)
+      [ role.container_prefix, version || config.version ].compact.join("-")
+    end
+
+    def filter_args(statuses: nil)
+      argumentize "--filter", filters(statuses: statuses)
+    end
+
+    def filters(statuses: nil)
+      [ "label=service=#{config.service}" ].tap do |filters|
+        filters << "label=destination=#{config.destination}" if config.destination
+        filters << "label=role=#{role}" if role
+        statuses&.each do |status|
+          filters << "status=#{status}"
+        end
+      end
+    end
+end

lib/kamal/commands/app/assets.rb

@@ -0,0 +1,51 @@
+module Kamal::Commands::App::Assets
+  def extract_assets
+    asset_container = "#{role.container_prefix}-assets"
+
+    combine \
+      make_directory(role.asset_extracted_path),
+      [ *docker(:stop, "-t 1", asset_container, "2> /dev/null"), "|| true" ],
+      docker(:run, "--name", asset_container, "--detach", "--rm", config.latest_image, "sleep 1000000"),
+      docker(:cp, "-L", "#{asset_container}:#{role.asset_path}/.", role.asset_extracted_path),
+      docker(:stop, "-t 1", asset_container),
+      by: "&&"
+  end
+
+  def sync_asset_volumes(old_version: nil)
+    new_extracted_path, new_volume_path = role.asset_extracted_path(config.version), role.asset_volume.host_path
+    if old_version.present?
+      old_extracted_path, old_volume_path = role.asset_extracted_path(old_version), role.asset_volume(old_version).host_path
+    end
+
+    commands = [ make_directory(new_volume_path), copy_contents(new_extracted_path, new_volume_path) ]
+
+    if old_version.present?
+      commands << copy_contents(new_extracted_path, old_volume_path, continue_on_error: true)
+      commands << copy_contents(old_extracted_path, new_volume_path, continue_on_error: true)
+    end
+
+    chain *commands
+  end
+
+  def clean_up_assets
+    chain \
+      find_and_remove_older_siblings(role.asset_extracted_path),
+      find_and_remove_older_siblings(role.asset_volume_path)
+  end
+
+  private
+    def find_and_remove_older_siblings(path)
+      [
+        :find,
+        Pathname.new(path).dirname.to_s,
+        "-maxdepth 1",
+        "-name", "'#{role.container_prefix}-*'",
+        "!", "-name", Pathname.new(path).basename.to_s,
+        "-exec rm -rf \"{}\" +"
+      ]
+    end
+
+    def copy_contents(source, destination, continue_on_error: false)
+      [ :cp, "-rnT", "#{source}", destination, *("|| true" if continue_on_error) ]
+    end
+end

lib/kamal/commands/app/containers.rb

@@ -0,0 +1,23 @@
+module Kamal::Commands::App::Containers
+  def list_containers
+    docker :container, :ls, "--all", *filter_args
+  end
+
+  def list_container_names
+    [ *list_containers, "--format", "'{{ .Names }}'" ]
+  end
+
+  def remove_container(version:)
+    pipe \
+      container_id_for(container_name: container_name(version)),
+      xargs(docker(:container, :rm))
+  end
+
+  def rename_container(version:, new_version:)
+    docker :rename, container_name(version), container_name(new_version)
+  end
+
+  def remove_containers
+    docker :container, :prune, "--force", *filter_args
+  end
+end

lib/kamal/commands/app/cord.rb

@@ -0,0 +1,22 @@
+module Kamal::Commands::App::Cord
+  def cord(version:)
+    pipe \
+      docker(:inspect, "-f '{{ range .Mounts }}{{printf \"%s %s\\n\" .Source .Destination}}{{ end }}'", container_name(version)),
+      [ :awk, "'$2 == \"#{role.cord_volume.container_path}\" {print $1}'" ]
+  end
+
+  def tie_cord(cord)
+    create_empty_file(cord)
+  end
+
+  def cut_cord(cord)
+    remove_directory(cord)
+  end
+
+  private
+    def create_empty_file(file)
+      chain \
+        make_directory_for(file),
+        [ :touch, file ]
+    end
+end

lib/kamal/commands/app/execution.rb

@@ -0,0 +1,27 @@
+module Kamal::Commands::App::Execution
+  def execute_in_existing_container(*command, interactive: false)
+    docker :exec,
+      ("-it" if interactive),
+      container_name,
+      *command
+  end
+
+  def execute_in_new_container(*command, interactive: false)
+    docker :run,
+      ("-it" if interactive),
+      "--rm",
+      *role&.env_args,
+      *config.volume_args,
+      *role&.option_args,
+      config.absolute_image,
+      *command
+  end
+
+  def execute_in_existing_container_over_ssh(*command, host:)
+    run_over_ssh execute_in_existing_container(*command, interactive: true), host: host
+  end
+
+  def execute_in_new_container_over_ssh(*command, host:)
+    run_over_ssh execute_in_new_container(*command, interactive: true), host: host
+  end
+end

lib/kamal/commands/app/images.rb

@@ -0,0 +1,13 @@
+module Kamal::Commands::App::Images
+  def list_images
+    docker :image, :ls, config.repository
+  end
+
+  def remove_images
+    docker :image, :prune, "--all", "--force", *filter_args
+  end
+
+  def tag_current_image_as_latest
+    docker :tag, config.absolute_image, config.latest_image
+  end
+end

lib/kamal/commands/app/logging.rb

@@ -0,0 +1,18 @@
+module Kamal::Commands::App::Logging
+  def logs(since: nil, lines: nil, grep: nil)
+    pipe \
+      current_running_container_id,
+      "xargs docker logs#{" --since #{since}" if since}#{" --tail #{lines}" if lines} 2>&1",
+      ("grep '#{grep}'" if grep)
+  end
+
+  def follow_logs(host:, lines: nil, grep: nil)
+    run_over_ssh \
+      pipe(
+        current_running_container_id,
+        "xargs docker logs --timestamps#{" --tail #{lines}" if lines} --follow 2>&1",
+        (%(grep "#{grep}") if grep)
+      ),
+      host: host
+  end
+end

lib/kamal/commands/auditor.rb

@@ -0,0 +1,30 @@
+class Kamal::Commands::Auditor < Kamal::Commands::Base
+  attr_reader :details
+
+  def initialize(config, **details)
+    super(config)
+    @details = details
+  end
+
+  # Runs remotely
+  def record(line, **details)
+    append \
+      [ :echo, audit_tags(**details).except(:version, :service_version).to_s, line ],
+      audit_log_file
+  end
+
+  def reveal
+    [ :tail, "-n", 50, audit_log_file ]
+  end
+
+  private
+    def audit_log_file
+      file = [ config.service, config.destination, "audit.log" ].compact.join("-")
+
+      "#{config.run_directory}/#{file}"
+    end
+
+    def audit_tags(**details)
+      tags(**self.details, **details)
+    end
+end

lib/kamal/commands/base.rb

@@ -0,0 +1,85 @@
+module Kamal::Commands
+  class Base
+    delegate :sensitive, :argumentize, to: Kamal::Utils
+
+    DOCKER_HEALTH_STATUS_FORMAT = "'{{if .State.Health}}{{.State.Health.Status}}{{else}}{{.State.Status}}{{end}}'"
+    DOCKER_HEALTH_LOG_FORMAT    = "'{{json .State.Health}}'"
+
+    attr_accessor :config
+
+    def initialize(config)
+      @config = config
+    end
+
+    def run_over_ssh(*command, host:)
+      "ssh".tap do |cmd|
+        if config.ssh.proxy && config.ssh.proxy.is_a?(Net::SSH::Proxy::Jump)
+          cmd << " -J #{config.ssh.proxy.jump_proxies}"
+        elsif config.ssh.proxy && config.ssh.proxy.is_a?(Net::SSH::Proxy::Command)
+          cmd << " -o ProxyCommand='#{config.ssh.proxy.command_line_template}'"
+        end
+        cmd << " -t #{config.ssh.user}@#{host} -p #{config.ssh.port} '#{command.join(" ")}'"
+      end
+    end
+
+    def container_id_for(container_name:, only_running: false)
+      docker :container, :ls, *("--all" unless only_running), "--filter", "name=^#{container_name}$", "--quiet"
+    end
+
+    def make_directory_for(remote_file)
+      make_directory Pathname.new(remote_file).dirname.to_s
+    end
+
+    def make_directory(path)
+      [ :mkdir, "-p", path ]
+    end
+
+    def remove_directory(path)
+      [ :rm, "-r", path ]
+    end
+
+    private
+      def combine(*commands, by: "&&")
+        commands
+          .compact
+          .collect { |command| Array(command) + [ by ] }.flatten # Join commands
+          .tap     { |commands| commands.pop } # Remove trailing combiner
+      end
+
+      def chain(*commands)
+        combine *commands, by: ";"
+      end
+
+      def pipe(*commands)
+        combine *commands, by: "|"
+      end
+
+      def append(*commands)
+        combine *commands, by: ">>"
+      end
+
+      def write(*commands)
+        combine *commands, by: ">"
+      end
+
+      def any(*commands)
+        combine *commands, by: "||"
+      end
+
+      def xargs(command)
+        [ :xargs, command ].flatten
+      end
+
+      def shell(command)
+        [ :sh, "-c", "'#{command.flatten.join(" ").gsub("'", "'\\''")}'" ]
+      end
+
+      def docker(*args)
+        args.compact.unshift :docker
+      end
+
+      def tags(**details)
+        Kamal::Tags.from_config(config, **details)
+      end
+  end
+end

lib/kamal/commands/builder.rb

@@ -0,0 +1,64 @@
+require "active_support/core_ext/string/filters"
+
+class Kamal::Commands::Builder < Kamal::Commands::Base
+  delegate :create, :remove, :push, :clean, :pull, :info, :validate_image, to: :target
+
+  def name
+    target.class.to_s.remove("Kamal::Commands::Builder::").underscore.inquiry
+  end
+
+  def target
+    case
+    when !config.builder.multiarch? && !config.builder.cached?
+      native
+    when !config.builder.multiarch? && config.builder.cached?
+      native_cached
+    when config.builder.local? && config.builder.remote?
+      multiarch_remote
+    when config.builder.remote?
+      native_remote
+    else
+      multiarch
+    end
+  end
+
+  def native
+    @native ||= Kamal::Commands::Builder::Native.new(config)
+  end
+
+  def native_cached
+    @native ||= Kamal::Commands::Builder::Native::Cached.new(config)
+  end
+
+  def native_remote
+    @native ||= Kamal::Commands::Builder::Native::Remote.new(config)
+  end
+
+  def multiarch
+    @multiarch ||= Kamal::Commands::Builder::Multiarch.new(config)
+  end
+
+  def multiarch_remote
+    @multiarch_remote ||= Kamal::Commands::Builder::Multiarch::Remote.new(config)
+  end
+
+
+  def ensure_local_dependencies_installed
+    if name.native?
+      ensure_local_docker_installed
+    else
+      combine \
+        ensure_local_docker_installed,
+        ensure_local_buildx_installed
+    end
+  end
+
+  private
+    def ensure_local_docker_installed
+      docker "--version"
+    end
+
+    def ensure_local_buildx_installed
+      docker :buildx, "version"
+    end
+end

lib/kamal/commands/builder/base.rb

@@ -0,0 +1,73 @@
+
+class Kamal::Commands::Builder::Base < Kamal::Commands::Base
+  class BuilderError < StandardError; end
+
+  delegate :argumentize, to: Kamal::Utils
+  delegate :args, :secrets, :dockerfile, :local_arch, :local_host, :remote_arch, :remote_host, :cache_from, :cache_to, :ssh, to: :builder_config
+
+  def clean
+    docker :image, :rm, "--force", config.absolute_image
+  end
+
+  def pull
+    docker :pull, config.absolute_image
+  end
+
+  def build_options
+    [ *build_tags, *build_cache, *build_labels, *build_args, *build_secrets, *build_dockerfile, *build_ssh ]
+  end
+
+  def build_context
+    config.builder.context
+  end
+
+  def validate_image
+    pipe \
+      docker(:inspect, "-f", "'{{ .Config.Labels.service }}'", config.absolute_image),
+      any(
+        [ :grep, "-x", config.service ],
+        "(echo \"Image #{config.absolute_image} is missing the 'service' label\" && exit 1)"
+      )
+  end
+
+
+  private
+    def build_tags
+      [ "-t", config.absolute_image, "-t", config.latest_image ]
+    end
+
+    def build_cache
+      if cache_to && cache_from
+        [ "--cache-to", cache_to,
+          "--cache-from", cache_from ]
+      end
+    end
+
+    def build_labels
+      argumentize "--label", { service: config.service }
+    end
+
+    def build_args
+      argumentize "--build-arg", args, sensitive: true
+    end
+
+    def build_secrets
+      argumentize "--secret", secrets.collect { |secret| [ "id", secret ] }
+    end
+
+    def build_dockerfile
+      if Pathname.new(File.expand_path(dockerfile)).exist?
+        argumentize "--file", dockerfile
+      else
+        raise BuilderError, "Missing #{dockerfile}"
+      end
+    end
+
+    def build_ssh
+      argumentize "--ssh", ssh if ssh.present?
+    end
+
+    def builder_config
+      config.builder
+    end
+end

lib/kamal/commands/builder/multiarch.rb

@@ -0,0 +1,37 @@
+class Kamal::Commands::Builder::Multiarch < Kamal::Commands::Builder::Base
+  def create
+    docker :buildx, :create, "--use", "--name", builder_name
+  end
+
+  def remove
+    docker :buildx, :rm, builder_name
+  end
+
+  def push
+    docker :buildx, :build,
+      "--push",
+      "--platform", platform_names,
+      "--builder", builder_name,
+      *build_options,
+      build_context
+  end
+
+  def info
+    combine \
+      docker(:context, :ls),
+      docker(:buildx, :ls)
+  end
+
+  private
+    def builder_name
+      "kamal-#{config.service}-multiarch"
+    end
+
+    def platform_names
+      if local_arch
+        "linux/#{local_arch}"
+      else
+        "linux/amd64,linux/arm64"
+      end
+    end
+end

lib/kamal/commands/builder/multiarch/remote.rb

@@ -0,0 +1,51 @@
+class Kamal::Commands::Builder::Multiarch::Remote < Kamal::Commands::Builder::Multiarch
+  def create
+    combine \
+      create_contexts,
+      create_local_buildx,
+      append_remote_buildx
+  end
+
+  def remove
+    combine \
+      remove_contexts,
+      super
+  end
+
+  private
+    def builder_name
+      super + "-remote"
+    end
+
+    def builder_name_with_arch(arch)
+      "#{builder_name}-#{arch}"
+    end
+
+    def create_local_buildx
+      docker :buildx, :create, "--name", builder_name, builder_name_with_arch(local_arch), "--platform", "linux/#{local_arch}"
+    end
+
+    def append_remote_buildx
+      docker :buildx, :create, "--append", "--name", builder_name, builder_name_with_arch(remote_arch), "--platform", "linux/#{remote_arch}"
+    end
+
+    def create_contexts
+      combine \
+        create_context(local_arch, local_host),
+        create_context(remote_arch, remote_host)
+    end
+
+    def create_context(arch, host)
+      docker :context, :create, builder_name_with_arch(arch), "--description", "'#{builder_name} #{arch} native host'", "--docker", "'host=#{host}'"
+    end
+
+    def remove_contexts
+      combine \
+        remove_context(local_arch),
+        remove_context(remote_arch)
+    end
+
+    def remove_context(arch)
+      docker :context, :rm, builder_name_with_arch(arch)
+    end
+end

lib/kamal/commands/builder/native.rb

@@ -0,0 +1,20 @@
+class Kamal::Commands::Builder::Native < Kamal::Commands::Builder::Base
+  def create
+    # No-op on native without cache
+  end
+
+  def remove
+    # No-op on native without cache
+  end
+
+  def push
+    combine \
+      docker(:build, *build_options, build_context),
+      docker(:push, config.absolute_image),
+      docker(:push, config.latest_image)
+  end
+
+  def info
+    # No-op on native
+  end
+end

lib/kamal/commands/builder/native/cached.rb

@@ -0,0 +1,16 @@
+class Kamal::Commands::Builder::Native::Cached < Kamal::Commands::Builder::Native
+  def create
+    docker :buildx, :create, "--use", "--driver=docker-container"
+  end
+
+  def remove
+    docker :buildx, :rm, builder_name
+  end
+
+  def push
+    docker :buildx, :build,
+      "--push",
+      *build_options,
+      build_context
+  end
+end

lib/kamal/commands/builder/native/remote.rb

@@ -0,0 +1,59 @@
+class Kamal::Commands::Builder::Native::Remote < Kamal::Commands::Builder::Native
+  def create
+    chain \
+      create_context,
+      create_buildx
+  end
+
+  def remove
+    chain \
+      remove_context,
+      remove_buildx
+  end
+
+  def push
+    docker :buildx, :build,
+      "--push",
+      "--platform", platform,
+      "--builder", builder_name,
+      *build_options,
+      build_context
+  end
+
+  def info
+    chain \
+      docker(:context, :ls),
+      docker(:buildx, :ls)
+  end
+
+
+  private
+    def builder_name
+      "kamal-#{config.service}-native-remote"
+    end
+
+    def builder_name_with_arch
+      "#{builder_name}-#{remote_arch}"
+    end
+
+    def platform
+      "linux/#{remote_arch}"
+    end
+
+    def create_context
+      docker :context, :create,
+        builder_name_with_arch, "--description", "'#{builder_name} #{remote_arch} native host'", "--docker", "'host=#{remote_host}'"
+    end
+
+    def remove_context
+      docker :context, :rm, builder_name_with_arch
+    end
+
+    def create_buildx
+      docker :buildx, :create, "--name", builder_name, builder_name_with_arch, "--platform", platform
+    end
+
+    def remove_buildx
+      docker :buildx, :rm, builder_name
+    end
+end

lib/kamal/commands/docker.rb

@@ -0,0 +1,30 @@
+class Kamal::Commands::Docker < Kamal::Commands::Base
+  # Install Docker using the https://github.com/docker/docker-install convenience script.
+  def install
+    pipe get_docker, :sh
+  end
+
+  # Checks the Docker client version. Fails if Docker is not installed.
+  def installed?
+    docker "-v"
+  end
+
+  # Checks the Docker server version. Fails if Docker is not running.
+  def running?
+    docker :version
+  end
+
+  # Do we have superuser access to install Docker and start system services?
+  def superuser?
+    [ '[ "${EUID:-$(id -u)}" -eq 0 ] || command -v sudo >/dev/null || command -v su >/dev/null' ]
+  end
+
+  private
+    def get_docker
+      shell \
+        any \
+          [ :curl, "-fsSL", "https://get.docker.com" ],
+          [ :wget, "-O -", "https://get.docker.com" ],
+          [ :echo, "\"exit 1\"" ]
+    end
+end

lib/kamal/commands/healthcheck.rb

@@ -0,0 +1,59 @@
+class Kamal::Commands::Healthcheck < Kamal::Commands::Base
+  def run
+    primary = config.role(config.primary_role)
+
+    docker :run,
+      "--detach",
+      "--name", container_name_with_version,
+      "--publish", "#{exposed_port}:#{config.healthcheck["port"]}",
+      "--label", "service=#{config.healthcheck_service}",
+      "-e", "KAMAL_CONTAINER_NAME=\"#{config.healthcheck_service}\"",
+      *primary.env_args,
+      *primary.health_check_args(cord: false),
+      *config.volume_args,
+      *primary.option_args,
+      config.absolute_image,
+      primary.cmd
+  end
+
+  def status
+    pipe container_id, xargs(docker(:inspect, "--format", DOCKER_HEALTH_STATUS_FORMAT))
+  end
+
+  def container_health_log
+    pipe container_id, xargs(docker(:inspect, "--format", DOCKER_HEALTH_LOG_FORMAT))
+  end
+
+  def logs
+    pipe container_id, xargs(docker(:logs, "--tail", log_lines, "2>&1"))
+  end
+
+  def stop
+    pipe container_id, xargs(docker(:stop))
+  end
+
+  def remove
+    pipe container_id, xargs(docker(:container, :rm))
+  end
+
+  private
+    def container_name_with_version
+      "#{config.healthcheck_service}-#{config.version}"
+    end
+
+    def container_id
+      container_id_for(container_name: container_name_with_version)
+    end
+
+    def health_url
+      "http://localhost:#{exposed_port}#{config.healthcheck["path"]}"
+    end
+
+    def exposed_port
+      config.healthcheck["exposed_port"]
+    end
+
+    def log_lines
+      config.healthcheck["log_lines"]
+    end
+end

lib/kamal/commands/hook.rb

@@ -0,0 +1,14 @@
+class Kamal::Commands::Hook < Kamal::Commands::Base
+  def run(hook, **details)
+    [ hook_file(hook), env: tags(**details).env ]
+  end
+
+  def hook_exists?(hook)
+    Pathname.new(hook_file(hook)).exist?
+  end
+
+  private
+    def hook_file(hook)
+      "#{config.hooks_path}/#{hook}"
+    end
+end

lib/kamal/commands/lock.rb

@@ -0,0 +1,64 @@
+require "active_support/duration"
+require "time"
+require "base64"
+
+class Kamal::Commands::Lock < Kamal::Commands::Base
+  def acquire(message, version)
+    combine \
+      [ :mkdir, lock_dir ],
+      write_lock_details(message, version)
+  end
+
+  def release
+    combine \
+      [ :rm, lock_details_file ],
+      [ :rm, "-r", lock_dir ]
+  end
+
+  def status
+    combine \
+      stat_lock_dir,
+      read_lock_details
+  end
+
+  private
+    def write_lock_details(message, version)
+      write \
+        [ :echo, "\"#{Base64.encode64(lock_details(message, version))}\"" ],
+        lock_details_file
+    end
+
+    def read_lock_details
+      pipe \
+        [ :cat, lock_details_file ],
+        [ :base64, "-d" ]
+    end
+
+    def stat_lock_dir
+      write \
+        [ :stat, lock_dir ],
+        "/dev/null"
+    end
+
+    def lock_dir
+      "#{config.run_directory}/lock-#{config.service}"
+    end
+
+    def lock_details_file
+      [ lock_dir, :details ].join("/")
+    end
+
+    def lock_details(message, version)
+      <<~DETAILS.strip
+        Locked by: #{locked_by} at #{Time.now.utc.iso8601}
+        Version: #{version}
+        Message: #{message}
+      DETAILS
+    end
+
+    def locked_by
+      Kamal::Git.user_name
+    rescue Errno::ENOENT
+      "Unknown"
+    end
+end

lib/kamal/commands/prune.rb

@@ -0,0 +1,46 @@
+require "active_support/duration"
+require "active_support/core_ext/numeric/time"
+
+class Kamal::Commands::Prune < Kamal::Commands::Base
+  def dangling_images
+    docker :image, :prune, "--force", "--filter", "label=service=#{config.service}"
+  end
+
+  def tagged_images
+    pipe \
+      docker(:image, :ls, *service_filter, "--format", "'{{.ID}} {{.Repository}}:{{.Tag}}'"),
+      "grep -v -w \"#{active_image_list}\"",
+      "while read image tag; do docker rmi $tag; done"
+  end
+
+  def app_containers(retain:)
+    pipe \
+      docker(:ps, "-q", "-a", *service_filter, *stopped_containers_filters),
+      "tail -n +#{retain + 1}",
+      "while read container_id; do docker rm $container_id; done"
+  end
+
+  def healthcheck_containers
+    docker :container, :prune, "--force", *healthcheck_service_filter
+  end
+
+  private
+    def stopped_containers_filters
+      [ "created", "exited", "dead" ].flat_map { |status| [ "--filter", "status=#{status}" ] }
+    end
+
+    def active_image_list
+      # Pull the images that are used by any containers
+      # Append repo:latest - to avoid deleting the latest tag
+      # Append repo:<none> - to avoid deleting dangling images that are in use. Unused dangling images are deleted separately
+      "$(docker container ls -a --format '{{.Image}}\\|' --filter label=service=#{config.service} | tr -d '\\n')#{config.latest_image}\\|#{config.repository}:<none>"
+    end
+
+    def service_filter
+      [ "--filter", "label=service=#{config.service}" ]
+    end
+
+    def healthcheck_service_filter
+      [ "--filter", "label=service=#{config.healthcheck_service}" ]
+    end
+end

lib/kamal/commands/registry.rb

@@ -0,0 +1,23 @@
+class Kamal::Commands::Registry < Kamal::Commands::Base
+  delegate :registry, to: :config
+
+  def login
+    docker :login,
+      registry["server"],
+      "-u", sensitive(Kamal::Utils.escape_shell_value(lookup("username"))),
+      "-p", sensitive(Kamal::Utils.escape_shell_value(lookup("password")))
+  end
+
+  def logout
+    docker :logout, registry["server"]
+  end
+
+  private
+    def lookup(key)
+      if registry[key].is_a?(Array)
+        ENV.fetch(registry[key].first).dup
+      else
+        registry[key]
+      end
+    end
+end

lib/kamal/commands/server.rb

@@ -0,0 +1,5 @@
+class Kamal::Commands::Server < Kamal::Commands::Base
+  def ensure_run_directory
+    [ :mkdir, "-p", config.run_directory ]
+  end
+end

lib/kamal/commands/traefik.rb

@@ -0,0 +1,124 @@
+class Kamal::Commands::Traefik < Kamal::Commands::Base
+  delegate :argumentize, :optionize, to: Kamal::Utils
+
+  DEFAULT_IMAGE = "traefik:v2.10"
+  CONTAINER_PORT = 80
+  DEFAULT_ARGS = {
+    "log.level" => "DEBUG"
+  }
+  DEFAULT_LABELS = {
+    # These ensure we serve a 502 rather than a 404 if no containers are available
+    "traefik.http.routers.catchall.entryPoints" => "http",
+    "traefik.http.routers.catchall.rule" => "PathPrefix(`/`)",
+    "traefik.http.routers.catchall.service" => "unavailable",
+    "traefik.http.routers.catchall.priority" => 1,
+    "traefik.http.services.unavailable.loadbalancer.server.port" => "0"
+  }
+
+  def run
+    docker :run, "--name traefik",
+      "--detach",
+      "--restart", "unless-stopped",
+      *publish_args,
+      "--volume", "/var/run/docker.sock:/var/run/docker.sock",
+      *env_args,
+      *config.logging_args,
+      *label_args,
+      *docker_options_args,
+      image,
+      "--providers.docker",
+      *cmd_option_args
+  end
+
+  def start
+    docker :container, :start, "traefik"
+  end
+
+  def stop
+    docker :container, :stop, "traefik"
+  end
+
+  def start_or_run
+    any start, run
+  end
+
+  def info
+    docker :ps, "--filter", "name=^traefik$"
+  end
+
+  def logs(since: nil, lines: nil, grep: nil)
+    pipe \
+      docker(:logs, "traefik", (" --since #{since}" if since), (" --tail #{lines}" if lines), "--timestamps", "2>&1"),
+      ("grep '#{grep}'" if grep)
+  end
+
+  def follow_logs(host:, grep: nil)
+    run_over_ssh pipe(
+      docker(:logs, "traefik", "--timestamps", "--tail", "10", "--follow", "2>&1"),
+      (%(grep "#{grep}") if grep)
+    ).join(" "), host: host
+  end
+
+  def remove_container
+    docker :container, :prune, "--force", "--filter", "label=org.opencontainers.image.title=Traefik"
+  end
+
+  def remove_image
+    docker :image, :prune, "--all", "--force", "--filter", "label=org.opencontainers.image.title=Traefik"
+  end
+
+  def port
+    "#{host_port}:#{CONTAINER_PORT}"
+  end
+
+  def env
+    Kamal::Configuration::Env.from_config \
+      config: config.traefik.fetch("env", {}),
+      secrets_file: File.join(config.host_env_directory, "traefik", "traefik.env")
+  end
+
+  def make_env_directory
+    make_directory(env.secrets_directory)
+  end
+
+  def remove_env_file
+    [ :rm, "-f", env.secrets_file ]
+  end
+
+  private
+    def publish_args
+      argumentize "--publish", port unless config.traefik["publish"] == false
+    end
+
+    def label_args
+      argumentize "--label", labels
+    end
+
+    def env_args
+      env.args
+    end
+
+    def labels
+      DEFAULT_LABELS.merge(config.traefik["labels"] || {})
+    end
+
+    def image
+      config.traefik.fetch("image") { DEFAULT_IMAGE }
+    end
+
+    def docker_options_args
+      optionize(config.traefik["options"] || {})
+    end
+
+    def cmd_option_args
+      if args = config.traefik["args"]
+        optionize DEFAULT_ARGS.merge(args), with: "="
+      else
+        optionize DEFAULT_ARGS, with: "="
+      end
+    end
+
+    def host_port
+      config.traefik["host_port"] || CONTAINER_PORT
+    end
+end

lib/kamal/configuration.rb

@@ -0,0 +1,332 @@
+require "active_support/ordered_options"
+require "active_support/core_ext/string/inquiry"
+require "active_support/core_ext/module/delegation"
+require "pathname"
+require "erb"
+require "net/ssh/proxy/jump"
+
+class Kamal::Configuration
+  delegate :service, :image, :servers, :labels, :registry, :stop_wait_time, :hooks_path, :logging, to: :raw_config, allow_nil: true
+  delegate :argumentize, :optionize, to: Kamal::Utils
+
+  attr_reader :destination, :raw_config
+
+  class << self
+    def create_from(config_file:, destination: nil, version: nil)
+      raw_config = load_config_files(config_file, *destination_config_file(config_file, destination))
+
+      new raw_config, destination: destination, version: version
+    end
+
+    private
+      def load_config_files(*files)
+        files.inject({}) { |config, file| config.deep_merge! load_config_file(file) }
+      end
+
+      def load_config_file(file)
+        if file.exist?
+          # Newer Psych doesn't load aliases by default
+          load_method = YAML.respond_to?(:unsafe_load) ? :unsafe_load : :load
+          YAML.send(load_method, ERB.new(IO.read(file)).result).symbolize_keys
+        else
+          raise "Configuration file not found in #{file}"
+        end
+      end
+
+      def destination_config_file(base_config_file, destination)
+        base_config_file.sub_ext(".#{destination}.yml") if destination
+      end
+  end
+
+  def initialize(raw_config, destination: nil, version: nil, validate: true)
+    @raw_config = ActiveSupport::InheritableOptions.new(raw_config)
+    @destination = destination
+    @declared_version = version
+    valid? if validate
+  end
+
+
+  def version=(version)
+    @declared_version = version
+  end
+
+  def version
+    @declared_version.presence || ENV["VERSION"] || git_version
+  end
+
+  def abbreviated_version
+    if version
+      # Don't abbreviate <sha>_uncommitted_<etc>
+      if version.include?("_")
+        version
+      else
+        version[0...7]
+      end
+    end
+  end
+
+  def minimum_version
+    raw_config.minimum_version
+  end
+
+
+  def roles
+    @roles ||= role_names.collect { |role_name| Role.new(role_name, config: self) }
+  end
+
+  def role(name)
+    roles.detect { |r| r.name == name.to_s }
+  end
+
+  def accessories
+    @accessories ||= raw_config.accessories&.keys&.collect { |name| Kamal::Configuration::Accessory.new(name, config: self) } || []
+  end
+
+  def accessory(name)
+    accessories.detect { |a| a.name == name.to_s }
+  end
+
+
+  def all_hosts
+    roles.flat_map(&:hosts).uniq
+  end
+
+  def primary_host
+    primary_role&.primary_host
+  end
+
+  def primary_role_name
+    raw_config.primary_role || "web"
+  end
+
+  def primary_role
+    role(primary_role_name)
+  end
+
+  def allow_empty_roles?
+    raw_config.allow_empty_roles
+  end
+
+  def traefik_roles
+    roles.select(&:running_traefik?)
+  end
+
+  def traefik_role_names
+    traefik_roles.flat_map(&:name)
+  end
+
+  def traefik_hosts
+    traefik_roles.flat_map(&:hosts).uniq
+  end
+
+  def repository
+    [ raw_config.registry["server"], image ].compact.join("/")
+  end
+
+  def absolute_image
+    "#{repository}:#{version}"
+  end
+
+  def latest_image
+    "#{repository}:#{[ "latest", *destination ].join("-")}"
+  end
+
+  def service_with_version
+    "#{service}-#{version}"
+  end
+
+  def require_destination?
+    raw_config.require_destination
+  end
+
+  def retain_containers
+    raw_config.retain_containers || 5
+  end
+
+
+  def volume_args
+    if raw_config.volumes.present?
+      argumentize "--volume", raw_config.volumes
+    else
+      []
+    end
+  end
+
+  def logging_args
+    if logging.present?
+      optionize({ "log-driver" => logging["driver"] }.compact) +
+        argumentize("--log-opt", logging["options"])
+    else
+      argumentize("--log-opt", { "max-size" => "10m" })
+    end
+  end
+
+
+  def boot
+    Kamal::Configuration::Boot.new(config: self)
+  end
+
+  def builder
+    Kamal::Configuration::Builder.new(config: self)
+  end
+
+  def traefik
+    raw_config.traefik || {}
+  end
+
+  def ssh
+    Kamal::Configuration::Ssh.new(config: self)
+  end
+
+  def sshkit
+    Kamal::Configuration::Sshkit.new(config: self)
+  end
+
+
+  def healthcheck
+    { "path" => "/up", "port" => 3000, "max_attempts" => 7, "exposed_port" => 3999, "cord" => "/tmp/kamal-cord", "log_lines" => 50 }.merge(raw_config.healthcheck || {})
+  end
+
+  def healthcheck_service
+    [ "healthcheck", service, destination ].compact.join("-")
+  end
+
+  def readiness_delay
+    raw_config.readiness_delay || 7
+  end
+
+  def run_id
+    @run_id ||= SecureRandom.hex(16)
+  end
+
+
+  def run_directory
+    raw_config.run_directory || ".kamal"
+  end
+
+  def run_directory_as_docker_volume
+    if Pathname.new(run_directory).absolute?
+      run_directory
+    else
+      File.join "$(pwd)", run_directory
+    end
+  end
+
+  def hooks_path
+    raw_config.hooks_path || ".kamal/hooks"
+  end
+
+  def asset_path
+    raw_config.asset_path
+  end
+
+
+  def host_env_directory
+    "#{run_directory}/env"
+  end
+
+  def env
+    raw_config.env || {}
+  end
+
+
+  def valid?
+    ensure_destination_if_required && ensure_required_keys_present && ensure_valid_kamal_version && ensure_retain_containers_valid && ensure_valid_service_name
+  end
+
+  def to_h
+    {
+      roles: role_names,
+      hosts: all_hosts,
+      primary_host: primary_host,
+      version: version,
+      repository: repository,
+      absolute_image: absolute_image,
+      service_with_version: service_with_version,
+      volume_args: volume_args,
+      ssh_options: ssh.to_h,
+      sshkit: sshkit.to_h,
+      builder: builder.to_h,
+      accessories: raw_config.accessories,
+      logging: logging_args,
+      healthcheck: healthcheck
+    }.compact
+  end
+
+
+  private
+    # Will raise ArgumentError if any required config keys are missing
+    def ensure_destination_if_required
+      if require_destination? && destination.nil?
+        raise ArgumentError, "You must specify a destination"
+      end
+
+      true
+    end
+
+    def ensure_required_keys_present
+      %i[ service image registry servers ].each do |key|
+        raise ArgumentError, "Missing required configuration for #{key}" unless raw_config[key].present?
+      end
+
+      if raw_config.registry["username"].blank?
+        raise ArgumentError, "You must specify a username for the registry in config/deploy.yml"
+      end
+
+      if raw_config.registry["password"].blank?
+        raise ArgumentError, "You must specify a password for the registry in config/deploy.yml (or set the ENV variable if that's used)"
+      end
+
+      unless role_names.include?(primary_role_name)
+        raise ArgumentError, "The primary_role #{primary_role_name} isn't defined"
+      end
+
+      if primary_role.hosts.empty?
+        raise ArgumentError, "No servers specified for the #{primary_role.name} primary_role"
+      end
+
+      unless allow_empty_roles?
+        roles.each do |role|
+          if role.hosts.empty?
+            raise ArgumentError, "No servers specified for the #{role.name} role. You can ignore this with allow_empty_roles: true"
+          end
+        end
+      end
+
+      true
+    end
+
+    def ensure_valid_service_name
+      raise ArgumentError, "Service name can only include alphanumeric characters, hyphens, and underscores" unless raw_config[:service] =~ /^[a-z0-9_-]+$/
+
+      true
+    end
+
+    def ensure_valid_kamal_version
+      if minimum_version && Gem::Version.new(minimum_version) > Gem::Version.new(Kamal::VERSION)
+        raise ArgumentError, "Current version is #{Kamal::VERSION}, minimum required is #{minimum_version}"
+      end
+
+      true
+    end
+
+    def ensure_retain_containers_valid
+      raise ArgumentError, "Must retain at least 1 container" if retain_containers < 1
+
+      true
+    end
+
+
+    def role_names
+      raw_config.servers.is_a?(Array) ? [ "web" ] : raw_config.servers.keys.sort
+    end
+
+    def git_version
+      @git_version ||=
+        if Kamal::Git.used?
+          [ Kamal::Git.revision, Kamal::Git.uncommitted_changes.present? ? "_uncommitted_#{SecureRandom.hex(8)}" : "" ].join
+        else
+          raise "Can't use commit hash as version, no git repository found in #{Dir.pwd}"
+        end
+    end
+end

lib/kamal/configuration/accessory.rb

@@ -0,0 +1,175 @@
+class Kamal::Configuration::Accessory
+  delegate :argumentize, :optionize, to: Kamal::Utils
+
+  attr_accessor :name, :specifics
+
+  def initialize(name, config:)
+    @name, @config, @specifics = name.inquiry, config, config.raw_config["accessories"][name]
+  end
+
+  def service_name
+    specifics["service"] || "#{config.service}-#{name}"
+  end
+
+  def image
+    specifics["image"]
+  end
+
+  def hosts
+    if (specifics.keys & [ "host", "hosts", "roles" ]).size != 1
+      raise ArgumentError, "Specify one of `host`, `hosts` or `roles` for accessory `#{name}`"
+    end
+
+    hosts_from_host || hosts_from_hosts || hosts_from_roles
+  end
+
+  def port
+    if port = specifics["port"]&.to_s
+      port.include?(":") ? port : "#{port}:#{port}"
+    end
+  end
+
+  def publish_args
+    argumentize "--publish", port if port
+  end
+
+  def labels
+    default_labels.merge(specifics["labels"] || {})
+  end
+
+  def label_args
+    argumentize "--label", labels
+  end
+
+  def env
+    Kamal::Configuration::Env.from_config \
+      config: specifics.fetch("env", {}),
+      secrets_file: File.join(config.host_env_directory, "accessories", "#{service_name}.env")
+  end
+
+  def env_args
+    env.args
+  end
+
+  def files
+    specifics["files"]&.to_h do |local_to_remote_mapping|
+      local_file, remote_file = local_to_remote_mapping.split(":")
+      [ expand_local_file(local_file), expand_remote_file(remote_file) ]
+    end || {}
+  end
+
+  def directories
+    specifics["directories"]&.to_h do |host_to_container_mapping|
+      host_path, container_path = host_to_container_mapping.split(":")
+      [ expand_host_path(host_path), container_path ]
+    end || {}
+  end
+
+  def volumes
+    specific_volumes + remote_files_as_volumes + remote_directories_as_volumes
+  end
+
+  def volume_args
+    argumentize "--volume", volumes
+  end
+
+  def option_args
+    if args = specifics["options"]
+      optionize args
+    else
+      []
+    end
+  end
+
+  def cmd
+    specifics["cmd"]
+  end
+
+  private
+    attr_accessor :config
+
+    def default_labels
+      { "service" => service_name }
+    end
+
+    def expand_local_file(local_file)
+      if local_file.end_with?("erb")
+        with_clear_env_loaded { read_dynamic_file(local_file) }
+      else
+        Pathname.new(File.expand_path(local_file)).to_s
+      end
+    end
+
+    def with_clear_env_loaded
+      env.clear.each { |k, v| ENV[k] = v }
+      yield
+    ensure
+      env.clear.each { |k, v| ENV.delete(k) }
+    end
+
+    def read_dynamic_file(local_file)
+      StringIO.new(ERB.new(IO.read(local_file)).result)
+    end
+
+    def expand_remote_file(remote_file)
+      service_name + remote_file
+    end
+
+    def specific_volumes
+      specifics["volumes"] || []
+    end
+
+    def remote_files_as_volumes
+      specifics["files"]&.collect do |local_to_remote_mapping|
+        _, remote_file = local_to_remote_mapping.split(":")
+        "#{service_data_directory + remote_file}:#{remote_file}"
+      end || []
+    end
+
+    def remote_directories_as_volumes
+      specifics["directories"]&.collect do |host_to_container_mapping|
+        host_path, container_path = host_to_container_mapping.split(":")
+        [ expand_host_path(host_path), container_path ].join(":")
+      end || []
+    end
+
+    def expand_host_path(host_path)
+      absolute_path?(host_path) ? host_path : "#{service_data_directory}/#{host_path}"
+    end
+
+    def absolute_path?(path)
+      Pathname.new(path).absolute?
+    end
+
+    def service_data_directory
+      "$PWD/#{service_name}"
+    end
+
+    def hosts_from_host
+      if specifics.key?("host")
+        host = specifics["host"]
+        if host
+          [ host ]
+        else
+          raise ArgumentError, "Missing host for accessory `#{name}`"
+        end
+      end
+    end
+
+    def hosts_from_hosts
+      if specifics.key?("hosts")
+        hosts = specifics["hosts"]
+        if hosts.is_a?(Array)
+          hosts
+        else
+          raise ArgumentError, "Hosts should be an Array for accessory `#{name}`"
+        end
+      end
+    end
+
+    def hosts_from_roles
+      if specifics.key?("roles")
+        specifics["roles"].flat_map { |role| config.role(role).hosts }
+      end
+    end
+end

lib/kamal/configuration/boot.rb

@@ -0,0 +1,20 @@
+class Kamal::Configuration::Boot
+  def initialize(config:)
+    @options = config.raw_config.boot || {}
+    @host_count = config.all_hosts.count
+  end
+
+  def limit
+    limit = @options["limit"]
+
+    if limit.to_s.end_with?("%")
+      [ @host_count * limit.to_i / 100, 1 ].max
+    else
+      limit
+    end
+  end
+
+  def wait
+    @options["wait"]
+  end
+end

lib/kamal/configuration/builder.rb

@@ -0,0 +1,118 @@
+class Kamal::Configuration::Builder
+  def initialize(config:)
+    @options = config.raw_config.builder || {}
+    @image = config.image
+    @server = config.registry["server"]
+
+    valid?
+  end
+
+  def to_h
+    @options
+  end
+
+  def multiarch?
+    @options["multiarch"] != false
+  end
+
+  def local?
+    !!@options["local"]
+  end
+
+  def remote?
+    !!@options["remote"]
+  end
+
+  def cached?
+    !!@options["cache"]
+  end
+
+  def args
+    @options["args"] || {}
+  end
+
+  def secrets
+    @options["secrets"] || []
+  end
+
+  def dockerfile
+    @options["dockerfile"] || "Dockerfile"
+  end
+
+  def context
+    @options["context"] || "."
+  end
+
+  def local_arch
+    @options["local"]["arch"] if local?
+  end
+
+  def local_host
+    @options["local"]["host"] if local?
+  end
+
+  def remote_arch
+    @options["remote"]["arch"] if remote?
+  end
+
+  def remote_host
+    @options["remote"]["host"] if remote?
+  end
+
+  def cache_from
+    if cached?
+      case @options["cache"]["type"]
+      when "gha"
+        cache_from_config_for_gha
+      when "registry"
+        cache_from_config_for_registry
+      end
+    end
+  end
+
+  def cache_to
+    if cached?
+      case @options["cache"]["type"]
+      when "gha"
+        cache_to_config_for_gha
+      when "registry"
+        cache_to_config_for_registry
+      end
+    end
+  end
+
+  def ssh
+    @options["ssh"]
+  end
+
+  private
+    def valid?
+      if @options["cache"] && @options["cache"]["type"]
+        raise ArgumentError, "Invalid cache type: #{@options["cache"]["type"]}" unless [ "gha", "registry" ].include?(@options["cache"]["type"])
+      end
+    end
+
+    def cache_image
+      @options["cache"]&.fetch("image", nil) || "#{@image}-build-cache"
+    end
+
+    def cache_image_ref
+      [ @server, cache_image ].compact.join("/")
+    end
+
+    def cache_from_config_for_gha
+      "type=gha"
+    end
+
+    def cache_from_config_for_registry
+      [ "type=registry", "ref=#{cache_image_ref}" ].compact.join(",")
+    end
+
+    def cache_to_config_for_gha
+      [ "type=gha", @options["cache"]&.fetch("options", nil) ].compact.join(",")
+    end
+
+    def cache_to_config_for_registry
+      [ "type=registry", @options["cache"]&.fetch("options", nil), "ref=#{cache_image_ref}" ].compact.join(",")
+    end
+end

lib/kamal/configuration/env.rb

@@ -0,0 +1,40 @@
+class Kamal::Configuration::Env
+  attr_reader :secrets_keys, :clear, :secrets_file
+  delegate :argumentize, to: Kamal::Utils
+
+  def self.from_config(config:, secrets_file: nil)
+    secrets_keys = config.fetch("secret", [])
+    clear = config.fetch("clear", config.key?("secret") ? {} : config)
+
+    new clear: clear, secrets_keys: secrets_keys, secrets_file: secrets_file
+  end
+
+  def initialize(clear:, secrets_keys:, secrets_file:)
+    @clear = clear
+    @secrets_keys = secrets_keys
+    @secrets_file = secrets_file
+  end
+
+  def args
+    [ "--env-file", secrets_file, *argumentize("--env", clear) ]
+  end
+
+  def secrets_io
+    StringIO.new(Kamal::EnvFile.new(secrets).to_s)
+  end
+
+  def secrets
+    @secrets ||= secrets_keys.to_h { |key| [ key, ENV.fetch(key) ] }
+  end
+
+  def secrets_directory
+    File.dirname(secrets_file)
+  end
+
+  def merge(other)
+    self.class.new \
+      clear: @clear.merge(other.clear),
+      secrets_keys: @secrets_keys | other.secrets_keys,
+      secrets_file: secrets_file
+  end
+end

lib/kamal/configuration/role.rb

@@ -0,0 +1,244 @@
+class Kamal::Configuration::Role
+  CORD_FILE = "cord"
+  delegate :argumentize, :optionize, to: Kamal::Utils
+
+  attr_accessor :name
+  alias to_s name
+
+  def initialize(name, config:)
+    @name, @config = name.inquiry, config
+  end
+
+  def primary_host
+    hosts.first
+  end
+
+  def hosts
+    @hosts ||= extract_hosts_from_config
+  end
+
+  def cmd
+    specializations["cmd"]
+  end
+
+  def option_args
+    if args = specializations["options"]
+      optionize args
+    else
+      []
+    end
+  end
+
+  def labels
+    default_labels.merge(traefik_labels).merge(custom_labels)
+  end
+
+  def label_args
+    argumentize "--label", labels
+  end
+
+  def logging_args
+    args = config.logging || {}
+    args.deep_merge!(specializations["logging"]) if specializations["logging"].present?
+
+    if args.any?
+      optionize({ "log-driver" => args["driver"] }.compact) +
+        argumentize("--log-opt", args["options"])
+    else
+      config.logging_args
+    end
+  end
+
+
+  def env
+    @env ||= base_env.merge(specialized_env)
+  end
+
+  def env_args
+    env.args
+  end
+
+  def asset_volume_args
+    asset_volume&.docker_args
+  end
+
+
+  def health_check_args(cord: true)
+    if health_check_cmd.present?
+      if cord && uses_cord?
+        optionize({ "health-cmd" => health_check_cmd_with_cord, "health-interval" => health_check_interval })
+          .concat(cord_volume.docker_args)
+      else
+        optionize({ "health-cmd" => health_check_cmd, "health-interval" => health_check_interval })
+      end
+    else
+      []
+    end
+  end
+
+  def health_check_cmd
+    health_check_options["cmd"] || http_health_check(port: health_check_options["port"], path: health_check_options["path"])
+  end
+
+  def health_check_cmd_with_cord
+    "(#{health_check_cmd}) && (stat #{cord_container_file} > /dev/null || exit 1)"
+  end
+
+  def health_check_interval
+    health_check_options["interval"] || "1s"
+  end
+
+
+  def running_traefik?
+    if specializations["traefik"].nil?
+      primary?
+    else
+      specializations["traefik"]
+    end
+  end
+
+  def primary?
+    self == @config.primary_role
+  end
+
+
+  def uses_cord?
+    running_traefik? && cord_volume && health_check_cmd.present?
+  end
+
+  def cord_host_directory
+    File.join config.run_directory_as_docker_volume, "cords", [ container_prefix, config.run_id ].join("-")
+  end
+
+  def cord_volume
+    if (cord = health_check_options["cord"])
+      @cord_volume ||= Kamal::Configuration::Volume.new \
+        host_path: File.join(config.run_directory, "cords", [ container_prefix, config.run_id ].join("-")),
+        container_path: cord
+    end
+  end
+
+  def cord_host_file
+    File.join cord_volume.host_path, CORD_FILE
+  end
+
+  def cord_container_directory
+    health_check_options.fetch("cord", nil)
+  end
+
+  def cord_container_file
+    File.join cord_volume.container_path, CORD_FILE
+  end
+
+
+  def container_name(version = nil)
+    [ container_prefix, version || config.version ].compact.join("-")
+  end
+
+  def container_prefix
+    [ config.service, name, config.destination ].compact.join("-")
+  end
+
+
+  def asset_path
+    specializations["asset_path"] || config.asset_path
+  end
+
+  def assets?
+    asset_path.present? && running_traefik?
+  end
+
+  def asset_volume(version = nil)
+    if assets?
+      Kamal::Configuration::Volume.new \
+        host_path: asset_volume_path(version), container_path: asset_path
+    end
+  end
+
+  def asset_extracted_path(version = nil)
+    File.join config.run_directory, "assets", "extracted", container_name(version)
+  end
+
+  def asset_volume_path(version = nil)
+    File.join config.run_directory, "assets", "volumes", container_name(version)
+  end
+
+  private
+    attr_accessor :config
+
+    def extract_hosts_from_config
+      if config.servers.is_a?(Array)
+        config.servers
+      else
+        servers = config.servers[name]
+        servers.is_a?(Array) ? servers : Array(servers["hosts"])
+      end
+    end
+
+    def default_labels
+      if config.destination
+        { "service" => config.service, "role" => name, "destination" => config.destination }
+      else
+        { "service" => config.service, "role" => name }
+      end
+    end
+
+    def traefik_labels
+      if running_traefik?
+        {
+          # Setting a service property ensures that the generated service name will be consistent between versions
+          "traefik.http.services.#{traefik_service}.loadbalancer.server.scheme" => "http",
+
+          "traefik.http.routers.#{traefik_service}.rule" => "PathPrefix(`/`)",
+          "traefik.http.routers.#{traefik_service}.priority" => "2",
+          "traefik.http.middlewares.#{traefik_service}-retry.retry.attempts" => "5",
+          "traefik.http.middlewares.#{traefik_service}-retry.retry.initialinterval" => "500ms",
+          "traefik.http.routers.#{traefik_service}.middlewares" => "#{traefik_service}-retry@docker"
+        }
+      else
+        {}
+      end
+    end
+
+    def traefik_service
+      container_prefix
+    end
+
+    def custom_labels
+      Hash.new.tap do |labels|
+        labels.merge!(config.labels) if config.labels.present?
+        labels.merge!(specializations["labels"]) if specializations["labels"].present?
+      end
+    end
+
+    def specializations
+      if config.servers.is_a?(Array) || config.servers[name].is_a?(Array)
+        {}
+      else
+        config.servers[name].except("hosts")
+      end
+    end
+
+    def specialized_env
+      Kamal::Configuration::Env.from_config config: specializations.fetch("env", {})
+    end
+
+    # Secrets are stored in an array, which won't merge by default, so have to do it by hand.
+    def base_env
+      Kamal::Configuration::Env.from_config \
+        config: config.env,
+        secrets_file: File.join(config.host_env_directory, "roles", "#{container_prefix}.env")
+    end
+
+    def http_health_check(port:, path:)
+      "curl -f #{URI.join("http://localhost:#{port}", path)} || exit 1" if path.present? || port.present?
+    end
+
+    def health_check_options
+      @health_check_options ||= begin
+        options = specializations["healthcheck"] || {}
+        options = config.healthcheck.merge(options) if running_traefik?
+        options
+      end
+    end
+end

lib/kamal/configuration/ssh.rb

@@ -0,0 +1,42 @@
+class Kamal::Configuration::Ssh
+  LOGGER = ::Logger.new(STDERR)
+
+  def initialize(config:)
+    @config = config.raw_config.ssh || {}
+  end
+
+  def user
+    config.fetch("user", "root")
+  end
+
+  def port
+    config.fetch("port", 22)
+  end
+
+  def proxy
+    if (proxy = config["proxy"])
+      Net::SSH::Proxy::Jump.new(proxy.include?("@") ? proxy : "root@#{proxy}")
+    elsif (proxy_command = config["proxy_command"])
+      Net::SSH::Proxy::Command.new(proxy_command)
+    end
+  end
+
+  def options
+    { user: user, port: port, proxy: proxy, logger: logger, keepalive: true, keepalive_interval: 30 }.compact
+  end
+
+  def to_h
+    options.except(:logger).merge(log_level: log_level)
+  end
+
+  private
+    attr_accessor :config
+
+    def logger
+      LOGGER.tap { |logger| logger.level = log_level }
+    end
+
+    def log_level
+      config.fetch("log_level", :fatal)
+    end
+end

lib/kamal/configuration/sshkit.rb

@@ -0,0 +1,20 @@
+class Kamal::Configuration::Sshkit
+  def initialize(config:)
+    @options = config.raw_config.sshkit || {}
+  end
+
+  def max_concurrent_starts
+    options.fetch("max_concurrent_starts", 30)
+  end
+
+  def pool_idle_timeout
+    options.fetch("pool_idle_timeout", 900)
+  end
+
+  def to_h
+    options
+  end
+
+  private
+    attr_accessor :options
+end

lib/kamal/configuration/volume.rb

@@ -0,0 +1,22 @@
+class Kamal::Configuration::Volume
+  attr_reader :host_path, :container_path
+  delegate :argumentize, to: Kamal::Utils
+
+  def initialize(host_path:, container_path:)
+    @host_path = host_path
+    @container_path = container_path
+  end
+
+  def docker_args
+    argumentize "--volume", "#{host_path_for_docker_volume}:#{container_path}"
+  end
+
+  private
+    def host_path_for_docker_volume
+      if Pathname.new(host_path).absolute?
+        host_path
+      else
+        File.join "$(pwd)", host_path
+      end
+    end
+end

lib/kamal/env_file.rb

@@ -0,0 +1,31 @@
+# Encode an env hash as a string where secret values have been looked up and all values escaped for Docker.
+class Kamal::EnvFile
+  def initialize(env)
+    @env = env
+  end
+
+  def to_s
+    env_file = StringIO.new.tap do |contents|
+      @env.each do |key, value|
+        contents << docker_env_file_line(key, value)
+      end
+    end.string
+
+    # Ensure the file has some contents to avoid the SSHKIT empty file warning
+    env_file.presence || "\n"
+  end
+
+  alias to_str to_s
+
+  private
+    def docker_env_file_line(key, value)
+      "#{key}=#{escape_docker_env_file_value(value)}\n"
+    end
+
+    # Escape a value to make it safe to dump in a docker file.
+    def escape_docker_env_file_value(value)
+      # Doublequotes are treated literally in docker env files
+      # so remove leading and trailing ones and unescape any others
+      value.to_s.dump[1..-2].gsub(/\\"/, "\"")
+    end
+end

lib/kamal/git.rb

@@ -0,0 +1,19 @@
+module Kamal::Git
+  extend self
+
+  def used?
+    system("git rev-parse")
+  end
+
+  def user_name
+    `git config user.name`.strip
+  end
+
+  def revision
+    `git rev-parse HEAD`.strip
+  end
+
+  def uncommitted_changes
+    `git status --porcelain`.strip
+  end
+end

lib/kamal/sshkit_with_ext.rb

@@ -0,0 +1,105 @@
+require "sshkit"
+require "sshkit/dsl"
+require "net/scp"
+require "active_support/core_ext/hash/deep_merge"
+require "json"
+
+class SSHKit::Backend::Abstract
+  def capture_with_info(*args, **kwargs)
+    capture(*args, **kwargs, verbosity: Logger::INFO)
+  end
+
+  def capture_with_debug(*args, **kwargs)
+    capture(*args, **kwargs, verbosity: Logger::DEBUG)
+  end
+
+  def capture_with_pretty_json(*args, **kwargs)
+    JSON.pretty_generate(JSON.parse(capture(*args, **kwargs)))
+  end
+
+  def puts_by_host(host, output, type: "App")
+    puts "#{type} Host: #{host}\n#{output}\n\n"
+  end
+
+  # Our execution pattern is for the CLI execute args lists returned
+  # from commands, but this doesn't support returning execution options
+  # from the command.
+  #
+  # Support this by using kwargs for CLI options and merging with the
+  # args-extracted options.
+  module CommandEnvMerge
+    private
+
+    # Override to merge options returned by commands in the args list with
+    # options passed by the CLI and pass them along as kwargs.
+    def command(args, options)
+      more_options, args = args.partition { |a| a.is_a? Hash }
+      more_options << options
+
+      build_command(args, **more_options.reduce(:deep_merge))
+    end
+
+    # Destructure options to pluck out env for merge
+    def build_command(args, env: nil, **options)
+      # Rely on native Ruby kwargs precedence rather than explicit Hash merges
+      SSHKit::Command.new(*args, **default_command_options, **options, env: env_for(env))
+    end
+
+    def default_command_options
+      { in: pwd_path, host: @host, user: @user, group: @group }
+    end
+
+    def env_for(env)
+      @env.to_h.merge(env.to_h)
+    end
+  end
+  prepend CommandEnvMerge
+end
+
+class SSHKit::Backend::Netssh::Configuration
+  attr_accessor :max_concurrent_starts
+end
+
+class SSHKit::Backend::Netssh
+  module LimitConcurrentStartsClass
+    attr_reader :start_semaphore
+
+    def configure(&block)
+      super &block
+      # Create this here to avoid lazy creation by multiple threads
+      if config.max_concurrent_starts
+        @start_semaphore = Concurrent::Semaphore.new(config.max_concurrent_starts)
+      end
+    end
+  end
+
+  class << self
+    prepend LimitConcurrentStartsClass
+  end
+
+  module LimitConcurrentStartsInstance
+    private
+      def with_ssh(&block)
+        host.ssh_options = self.class.config.ssh_options.merge(host.ssh_options || {})
+        self.class.pool.with(
+          method(:start_with_concurrency_limit),
+          String(host.hostname),
+          host.username,
+          host.netssh_options,
+          &block
+        )
+      end
+
+      def start_with_concurrency_limit(*args)
+        if self.class.start_semaphore
+          self.class.start_semaphore.acquire do
+            Net::SSH.start(*args)
+          end
+        else
+          Net::SSH.start(*args)
+        end
+      end
+  end
+
+  prepend LimitConcurrentStartsInstance
+end

lib/kamal/tags.rb

@@ -0,0 +1,39 @@
+require "time"
+
+class Kamal::Tags
+  attr_reader :config, :tags
+
+  class << self
+    def from_config(config, **extra)
+      new(**default_tags(config), **extra)
+    end
+
+    def default_tags(config)
+      { recorded_at: Time.now.utc.iso8601,
+        performer: `whoami`.chomp,
+        destination: config.destination,
+        version: config.version,
+        service_version: service_version(config) }
+    end
+
+    def service_version(config)
+      [ config.service, config.abbreviated_version ].compact.join("@")
+    end
+  end
+
+  def initialize(**tags)
+    @tags = tags.compact
+  end
+
+  def env
+    tags.transform_keys { |detail| "KAMAL_#{detail.upcase}" }
+  end
+
+  def to_s
+    tags.values.map { |value| "[#{value}]" }.join(" ")
+  end
+
+  def except(*tags)
+    self.class.new(**self.tags.except(*tags))
+  end
+end

lib/kamal/utils.rb

@@ -0,0 +1,77 @@
+module Kamal::Utils
+  extend self
+
+  DOLLAR_SIGN_WITHOUT_SHELL_EXPANSION_REGEX = /\$(?!{[^\}]*\})/
+
+  # Return a list of escaped shell arguments using the same named argument against the passed attributes (hash or array).
+  def argumentize(argument, attributes, sensitive: false)
+    Array(attributes).flat_map do |key, value|
+      if value.present?
+        attr = "#{key}=#{escape_shell_value(value)}"
+        attr = self.sensitive(attr, redaction: "#{key}=[REDACTED]") if sensitive
+        [ argument, attr ]
+      else
+        [ argument, key ]
+      end
+    end
+  end
+
+  # Returns a list of shell-dashed option arguments. If the value is true, it's treated like a value-less option.
+  def optionize(args, with: nil)
+    options = if with
+      flatten_args(args).collect { |(key, value)| value == true ? "--#{key}" : "--#{key}#{with}#{escape_shell_value(value)}" }
+    else
+      flatten_args(args).collect { |(key, value)| [ "--#{key}", value == true ? nil : escape_shell_value(value) ] }
+    end
+
+    options.flatten.compact
+  end
+
+  # Flattens a one-to-many structure into an array of two-element arrays each containing a key-value pair
+  def flatten_args(args)
+    args.flat_map { |key, value| value.try(:map) { |entry| [ key, entry ] } || [ [ key, value ] ] }
+  end
+
+  # Marks sensitive values for redaction in logs and human-visible output.
+  # Pass `redaction:` to change the default `"[REDACTED]"` redaction, e.g.
+  # `sensitive "#{arg}=#{secret}", redaction: "#{arg}=xxxx"
+  def sensitive(...)
+    Kamal::Utils::Sensitive.new(...)
+  end
+
+  def redacted(value)
+    case
+    when value.respond_to?(:redaction)
+      value.redaction
+    when value.respond_to?(:transform_values)
+      value.transform_values { |value| redacted value }
+    when value.respond_to?(:map)
+      value.map { |element| redacted element }
+    else
+      value
+    end
+  end
+
+  # Escape a value to make it safe for shell use.
+  def escape_shell_value(value)
+    value.to_s.dump
+      .gsub(/`/, '\\\\`')
+      .gsub(DOLLAR_SIGN_WITHOUT_SHELL_EXPANSION_REGEX, '\$')
+  end
+
+  # Apply a list of host or role filters, including wildcard matches
+  def filter_specific_items(filters, items)
+    matches = []
+
+    Array(filters).select do |filter|
+      matches += Array(items).select do |item|
+        # Only allow * for a wildcard
+        pattern = Regexp.escape(filter).gsub('\*', ".*")
+        # items are roles or hosts
+        (item.respond_to?(:name) ? item.name : item).match(/^#{pattern}$/)
+      end
+    end
+
+    matches
+  end
+end

lib/kamal/utils/sensitive.rb

@@ -0,0 +1,20 @@
+require "active_support/core_ext/module/delegation"
+require "sshkit"
+
+class Kamal::Utils::Sensitive
+  # So SSHKit knows to redact these values.
+  include SSHKit::Redaction
+
+  attr_reader :unredacted, :redaction
+  delegate :to_s, to: :unredacted
+  delegate :inspect, to: :redaction
+
+  def initialize(value, redaction: "[REDACTED]")
+    @unredacted, @redaction = value, redaction
+  end
+
+  # Sensitive values won't leak into YAML output.
+  def encode_with(coder)
+    coder.represent_scalar nil, redaction
+  end
+end

lib/kamal/version.rb

@@ -0,0 +1,3 @@
+module Kamal
+  VERSION = "1.4.0"
+end

lib/mrsk.rb

@@ -1,8 +0,0 @@
-module Mrsk
-end
-
-require "mrsk/version"
-require "mrsk/engine"
-
-require "mrsk/configuration"
-require "mrsk/commands"

lib/mrsk/commands.rb

@@ -1,13 +0,0 @@
-module Mrsk::Commands
-  class Base
-    attr_accessor :config
-
-    def initialize(config)
-      @config = config
-    end
-  end
-end
-
-require "mrsk/commands/app"
-require "mrsk/commands/traefik"
-require "mrsk/commands/registry"

lib/mrsk/commands/app.rb

@@ -1,22 +0,0 @@
-class Mrsk::Commands::App < Mrsk::Commands::Base
-  def push
-    # TODO: Run 'docker buildx create --use' when needed
-    "docker buildx build --push --platform=linux/amd64,linux/arm64 -t #{config.absolute_image} ."
-  end
-
-  def pull
-    "docker pull #{config.absolute_image}"
-  end
-
-  def start
-    "docker run -d --rm --name #{config.service_with_version} #{config.envs} #{config.labels} #{config.absolute_image}"
-  end
-
-  def stop
-    "docker ps -q --filter label=service=#{config.service} | xargs docker stop"
-  end
-
-  def info
-    "docker ps --filter label=service=#{config.service}"
-  end
-end

lib/mrsk/commands/registry.rb

@@ -1,5 +0,0 @@
-class Mrsk::Commands::Registry < Mrsk::Commands::Base
-  def login
-    "docker login #{config.registry["server"]} -u #{config.registry["username"]} -p #{config.registry["password"]}"
-  end
-end

lib/mrsk/commands/traefik.rb

@@ -1,17 +0,0 @@
-class Mrsk::Commands::Traefik < Mrsk::Commands::Base
-  def start
-    "docker run --name traefik " + 
-      "--rm -d " +
-      "-p 80:80 " +
-      "-v /var/run/docker.sock:/var/run/docker.sock " +
-      "traefik --providers.docker"
-  end
-
-  def stop
-    "docker container stop traefik"
-  end
-
-  def info
-    "docker ps --filter name=traefik"
-  end
-end

lib/mrsk/configuration.rb

@@ -1,78 +0,0 @@
-require "active_support/ordered_options"
-
-class Mrsk::Configuration
-  delegate :service, :image, :env, :registry, :ssh_user, to: :config, allow_nil: true
-
-  def self.load_file(file)
-    if file.exist?
-      new YAML.load_file(file).symbolize_keys
-    else
-      raise "Configuration file not found in #{file}"
-    end
-  end
-
-  def initialize(config)
-    @config = ActiveSupport::InheritableOptions.new(config)
-    ensure_required_keys_present
-  end
-
-  def servers
-    ENV["SERVERS"] || config.servers
-  end
-
-  def version
-    @version ||= ENV["VERSION"] || `git rev-parse HEAD`.strip
-  end
-
-  def absolute_image
-    [ config.registry["server"], image_with_version ].compact.join("/")
-  end
-
-  def image_with_version
-    "#{image}:#{version}"
-  end
-
-  def service_with_version
-    "#{service}-#{version}"
-  end
-
-  def envs
-    parameterize "-e", \
-      { "RAILS_MASTER_KEY" => master_key }.merge(env || {})
-  end
-
-  def labels
-    parameterize "--label", \
-      "service" => service,
-      "traefik.http.routers.#{service}.rule" => "'PathPrefix(`/`)'",
-      "traefik.http.services.#{service}.loadbalancer.healthcheck.path" => "/up",
-      "traefik.http.services.#{service}.loadbalancer.healthcheck.interval" => "1s",
-      "traefik.http.middlewares.#{service}.retry.attempts" => "3",
-      "traefik.http.middlewares.#{service}.retry.initialinterval" => "500ms"
-  end
-
-  def ssh_options
-    { user: config.ssh_user || "root", auth_methods: [ "publickey" ] }
-  end
-
-  private
-    attr_accessor :config
-
-    def ensure_required_keys_present
-      %i[ service image registry ].each do |key|
-        raise ArgumentError, "Missing required configuration for #{key}" unless config[key].present?
-      end
-
-      %w[ username password ].each do |key|
-        raise ArgumentError, "Missing required configuration for registry/#{key}" unless config.registry[key].present?
-      end      
-    end
-
-    def parameterize(param, hash)
-      hash.collect { |k, v| "#{param} #{k}=#{v}" }.join(" ")
-    end
-
-    def master_key
-      ENV["RAILS_MASTER_KEY"] || File.read(Rails.root.join("config/master.key"))
-    end
-end

lib/mrsk/engine.rb

@@ -1,4 +0,0 @@
-module Mrsk
-  class Engine < ::Rails::Engine
-  end
-end

lib/mrsk/version.rb

@@ -1,3 +0,0 @@
-module Mrsk
-  VERSION = "0.0.1"
-end

lib/tasks/mrsk/app.rake

@@ -1,31 +0,0 @@
-require_relative "setup"
-
-app = Mrsk::Commands::App.new(MRSK_CONFIG)
-
-namespace :mrsk do
-  namespace :app do
-    desc "Build and push app image to servers"
-    task :push do
-      run_locally             { execute app.push }
-      on(MRSK_CONFIG.servers) { execute app.pull }
-    end
-
-    desc "Start app on servers"
-    task :start do
-      on(MRSK_CONFIG.servers) { execute app.start }
-    end
-
-    desc "Stop app on servers"
-    task :stop do
-      on(MRSK_CONFIG.servers) { execute app.stop, raise_on_non_zero_exit: false }
-    end
-
-    desc "Restart app on servers"
-    task restart: %i[ stop start ]
-
-    desc "Display information about app containers"
-    task :info do
-      on(MRSK_CONFIG.servers) { |host| puts "Host: #{host}\n" + capture(app.info) + "\n\n" }
-    end
-  end
-end

lib/tasks/mrsk/mrsk.rake

@@ -1,12 +0,0 @@
-namespace :mrsk do
-  desc "Push the latest version of the app, ensure Traefik is running, then restart app"
-  task deploy: [ "app:push", "traefik:start", "app:restart" ]
-
-  desc "Display information about Traefik and app containers"
-  task info: [ "traefik:info", "app:info" ]
-
-  desc "Create config stub"
-  task :init do
-    Rails.root.join("config/deploy.yml")
-  end
-end

lib/tasks/mrsk/registry.rake

@@ -1,13 +0,0 @@
-require_relative "setup"
-
-registry = Mrsk::Commands::Registry.new(MRSK_CONFIG)
-
-namespace :mrsk do
-  namespace :registry do
-    desc "Login to the registry locally and remotely"
-    task :login do
-      run_locally             { execute registry.login }
-      on(MRSK_CONFIG.servers) { execute registry.login }
-    end
-  end
-end

lib/tasks/mrsk/setup.rb

@@ -1,8 +0,0 @@
-require "sshkit"
-require "sshkit/dsl"
-
-include SSHKit::DSL
-
-MRSK_CONFIG = Mrsk::Configuration.load_file(Rails.root.join("config/deploy.yml"))
-
-SSHKit::Backend::Netssh.configure { |ssh| ssh.ssh_options = MRSK_CONFIG.ssh_options }

lib/tasks/mrsk/traefik.rake

@@ -1,25 +0,0 @@
-require_relative "setup"
-
-traefik = Mrsk::Commands::Traefik.new(MRSK_CONFIG)
-
-namespace :mrsk do
-  namespace :traefik do
-    desc "Start Traefik"
-    task :start do
-      on(MRSK_CONFIG.servers) { execute traefik.start, raise_on_non_zero_exit: false }
-    end
-
-    desc "Stop Traefik"
-    task :stop do
-      on(MRSK_CONFIG.servers) { execute traefik.stop, raise_on_non_zero_exit: false }
-    end
-
-    desc "Restart Traefik"
-    task restart: %i[ stop start ]
-
-    desc "Display information about Traefik containers"
-    task :info do
-      on(MRSK_CONFIG.servers) { |host| puts "Host: #{host}\n" + capture(traefik.info) + "\n\n" }
-    end
-  end
-end

mrsk.gemspec

@@ -1,16 +0,0 @@
-require_relative "lib/mrsk/version"
-
-Gem::Specification.new do |spec|
-  spec.name        = "mrsk"
-  spec.version     = Mrsk::VERSION
-  spec.authors     = [ "David Heinemeier Hansson" ]
-  spec.email       = "dhh@hey.com"
-  spec.homepage    = "https://github.com/rails/mrsk"
-  spec.summary     = "Deploy Docker containers with zero downtime to any host."
-  spec.license     = "MIT"
-
-  spec.files = Dir["lib/**/*", "MIT-LICENSE", "README.md"]
-
-  spec.add_dependency "railties", ">= 7.0.0"
-  spec.add_dependency "sshkit", "~> 1.21"
-end

test/cli/accessory_test.rb

@@ -0,0 +1,183 @@
+require_relative "cli_test_case"
+
+class CliAccessoryTest < CliTestCase
+  test "boot" do
+    Kamal::Cli::Accessory.any_instance.expects(:directories).with("mysql")
+    Kamal::Cli::Accessory.any_instance.expects(:upload).with("mysql")
+
+    run_command("boot", "mysql").tap do |output|
+      assert_match /docker login.*on 1.1.1.3/, output
+      assert_match "docker run --name app-mysql --detach --restart unless-stopped --log-opt max-size=\"10m\" --publish 3306:3306 --env-file .kamal/env/accessories/app-mysql.env --env MYSQL_ROOT_HOST=\"%\" --volume $PWD/app-mysql/etc/mysql/my.cnf:/etc/mysql/my.cnf --volume $PWD/app-mysql/data:/var/lib/mysql --label service=\"app-mysql\" mysql:5.7 on 1.1.1.3", output
+    end
+  end
+
+  test "boot all" do
+    Kamal::Cli::Accessory.any_instance.expects(:directories).with("mysql")
+    Kamal::Cli::Accessory.any_instance.expects(:upload).with("mysql")
+    Kamal::Cli::Accessory.any_instance.expects(:directories).with("redis")
+    Kamal::Cli::Accessory.any_instance.expects(:upload).with("redis")
+
+    run_command("boot", "all").tap do |output|
+      assert_match /docker login.*on 1.1.1.3/, output
+      assert_match /docker login.*on 1.1.1.1/, output
+      assert_match /docker login.*on 1.1.1.2/, output
+      assert_match "docker run --name app-mysql --detach --restart unless-stopped --log-opt max-size=\"10m\" --publish 3306:3306 --env-file .kamal/env/accessories/app-mysql.env --env MYSQL_ROOT_HOST=\"%\" --volume $PWD/app-mysql/etc/mysql/my.cnf:/etc/mysql/my.cnf --volume $PWD/app-mysql/data:/var/lib/mysql --label service=\"app-mysql\" mysql:5.7 on 1.1.1.3", output
+      assert_match "docker run --name app-redis --detach --restart unless-stopped --log-opt max-size=\"10m\" --publish 6379:6379 --env-file .kamal/env/accessories/app-redis.env --volume $PWD/app-redis/data:/data --label service=\"app-redis\" redis:latest on 1.1.1.1", output
+      assert_match "docker run --name app-redis --detach --restart unless-stopped --log-opt max-size=\"10m\" --publish 6379:6379 --env-file .kamal/env/accessories/app-redis.env --volume $PWD/app-redis/data:/data --label service=\"app-redis\" redis:latest on 1.1.1.2", output
+    end
+  end
+
+  test "upload" do
+    run_command("upload", "mysql").tap do |output|
+      assert_match "mkdir -p app-mysql/etc/mysql", output
+      assert_match "test/fixtures/files/my.cnf app-mysql/etc/mysql/my.cnf", output
+      assert_match "chmod 755 app-mysql/etc/mysql/my.cnf", output
+    end
+  end
+
+  test "directories" do
+    assert_match "mkdir -p $PWD/app-mysql/data", run_command("directories", "mysql")
+  end
+
+  test "reboot" do
+    Kamal::Commands::Registry.any_instance.expects(:login)
+    Kamal::Cli::Accessory.any_instance.expects(:stop).with("mysql")
+    Kamal::Cli::Accessory.any_instance.expects(:remove_container).with("mysql")
+    Kamal::Cli::Accessory.any_instance.expects(:boot).with("mysql", login: false)
+
+    run_command("reboot", "mysql")
+  end
+
+  test "reboot all" do
+    Kamal::Commands::Registry.any_instance.expects(:login).times(3)
+    Kamal::Cli::Accessory.any_instance.expects(:stop).with("mysql")
+    Kamal::Cli::Accessory.any_instance.expects(:remove_container).with("mysql")
+    Kamal::Cli::Accessory.any_instance.expects(:boot).with("mysql", login: false)
+    Kamal::Cli::Accessory.any_instance.expects(:stop).with("redis")
+    Kamal::Cli::Accessory.any_instance.expects(:remove_container).with("redis")
+    Kamal::Cli::Accessory.any_instance.expects(:boot).with("redis", login: false)
+
+    run_command("reboot", "all")
+  end
+
+  test "start" do
+    assert_match "docker container start app-mysql", run_command("start", "mysql")
+  end
+
+  test "stop" do
+    assert_match "docker container stop app-mysql", run_command("stop", "mysql")
+  end
+
+  test "restart" do
+    Kamal::Cli::Accessory.any_instance.expects(:stop).with("mysql")
+    Kamal::Cli::Accessory.any_instance.expects(:start).with("mysql")
+
+    run_command("restart", "mysql")
+  end
+
+  test "details" do
+    assert_match "docker ps --filter label=service=app-mysql", run_command("details", "mysql")
+  end
+
+  test "details with non-existent accessory" do
+    assert_equal "No accessory by the name of 'hello' (options: mysql and redis)", stderred { run_command("details", "hello") }
+  end
+
+  test "details with all" do
+    run_command("details", "all").tap do |output|
+      assert_match "docker ps --filter label=service=app-mysql", output
+      assert_match "docker ps --filter label=service=app-redis", output
+    end
+  end
+
+  test "exec" do
+    run_command("exec", "mysql", "mysql -v").tap do |output|
+      assert_match "Launching command from new container", output
+      assert_match "mysql -v", output
+    end
+  end
+
+  test "exec with reuse" do
+    run_command("exec", "mysql", "--reuse", "mysql -v").tap do |output|
+      assert_match "Launching command from existing container", output
+      assert_match "docker exec app-mysql mysql -v", output
+    end
+  end
+
+  test "logs" do
+    SSHKit::Backend::Abstract.any_instance.stubs(:exec)
+      .with("ssh -t root@1.1.1.3 'docker logs app-mysql --timestamps --tail 10 2>&1'")
+
+    assert_match "docker logs app-mysql  --tail 100 --timestamps 2>&1", run_command("logs", "mysql")
+  end
+
+  test "logs with follow" do
+    SSHKit::Backend::Abstract.any_instance.stubs(:exec)
+      .with("ssh -t root@1.1.1.3 -p 22 'docker logs app-mysql --timestamps --tail 10 --follow 2>&1'")
+
+    assert_match "docker logs app-mysql --timestamps --tail 10 --follow 2>&1", run_command("logs", "mysql", "--follow")
+  end
+
+  test "remove with confirmation" do
+    Kamal::Cli::Accessory.any_instance.expects(:stop).with("mysql")
+    Kamal::Cli::Accessory.any_instance.expects(:remove_container).with("mysql")
+    Kamal::Cli::Accessory.any_instance.expects(:remove_image).with("mysql")
+    Kamal::Cli::Accessory.any_instance.expects(:remove_service_directory).with("mysql")
+
+    run_command("remove", "mysql", "-y")
+  end
+
+  test "remove all with confirmation" do
+    Kamal::Cli::Accessory.any_instance.expects(:stop).with("mysql")
+    Kamal::Cli::Accessory.any_instance.expects(:remove_container).with("mysql")
+    Kamal::Cli::Accessory.any_instance.expects(:remove_image).with("mysql")
+    Kamal::Cli::Accessory.any_instance.expects(:remove_service_directory).with("mysql")
+    Kamal::Cli::Accessory.any_instance.expects(:stop).with("redis")
+    Kamal::Cli::Accessory.any_instance.expects(:remove_container).with("redis")
+    Kamal::Cli::Accessory.any_instance.expects(:remove_image).with("redis")
+    Kamal::Cli::Accessory.any_instance.expects(:remove_service_directory).with("redis")
+
+    run_command("remove", "all", "-y")
+  end
+
+  test "remove_container" do
+    assert_match "docker container prune --force --filter label=service=app-mysql", run_command("remove_container", "mysql")
+  end
+
+  test "remove_image" do
+    assert_match "docker image rm --force mysql", run_command("remove_image", "mysql")
+  end
+
+  test "remove_service_directory" do
+    assert_match "rm -rf app-mysql", run_command("remove_service_directory", "mysql")
+  end
+
+  test "hosts param respected" do
+    Kamal::Cli::Accessory.any_instance.expects(:directories).with("redis")
+    Kamal::Cli::Accessory.any_instance.expects(:upload).with("redis")
+
+    run_command("boot", "redis", "--hosts", "1.1.1.1").tap do |output|
+      assert_match /docker login.*on 1.1.1.1/, output
+      assert_no_match /docker login.*on 1.1.1.2/, output
+      assert_match "docker run --name app-redis --detach --restart unless-stopped --log-opt max-size=\"10m\" --publish 6379:6379 --env-file .kamal/env/accessories/app-redis.env --volume $PWD/app-redis/data:/data --label service=\"app-redis\" redis:latest on 1.1.1.1", output
+      assert_no_match "docker run --name app-redis --detach --restart unless-stopped --log-opt max-size=\"10m\" --publish 6379:6379 --env-file .kamal/env/accessories/app-redis.env --volume $PWD/app-redis/data:/data --label service=\"app-redis\" redis:latest on 1.1.1.2", output
+    end
+  end
+
+  test "hosts param intersected with configuration" do
+    Kamal::Cli::Accessory.any_instance.expects(:directories).with("redis")
+    Kamal::Cli::Accessory.any_instance.expects(:upload).with("redis")
+
+    run_command("boot", "redis", "--hosts", "1.1.1.1,1.1.1.3").tap do |output|
+      assert_match /docker login.*on 1.1.1.1/, output
+      assert_no_match /docker login.*on 1.1.1.3/, output
+      assert_match "docker run --name app-redis --detach --restart unless-stopped --log-opt max-size=\"10m\" --publish 6379:6379 --env-file .kamal/env/accessories/app-redis.env --volume $PWD/app-redis/data:/data --label service=\"app-redis\" redis:latest on 1.1.1.1", output
+      assert_no_match "docker run --name app-redis --detach --restart unless-stopped --log-opt max-size=\"10m\" --publish 6379:6379 --env-file .kamal/env/accessories/app-redis.env --volume $PWD/app-redis/data:/data --label service=\"app-redis\" redis:latest on 1.1.1.3", output
+    end
+  end
+
+  private
+    def run_command(*command)
+      stdouted { Kamal::Cli::Accessory.start([ *command, "-c", "test/fixtures/deploy_with_accessories.yml" ]) }
+    end
+end

test/cli/app_test.rb

@@ -0,0 +1,249 @@
+require_relative "cli_test_case"
+
+class CliAppTest < CliTestCase
+  test "boot" do
+    stub_running
+    run_command("boot").tap do |output|
+      assert_match "docker tag dhh/app:latest dhh/app:latest", output
+      assert_match /docker run --detach --restart unless-stopped --name app-web-latest --hostname 1.1.1.1-[0-9a-f]{12} /, output
+      assert_match "docker container ls --all --filter name=^app-web-123$ --quiet | xargs docker stop", output
+    end
+  end
+
+  test "boot will rename if same version is already running" do
+    Object.any_instance.stubs(:sleep)
+    run_command("details") # Preheat Kamal const
+
+    SSHKit::Backend::Abstract.any_instance.expects(:capture_with_info)
+      .with(:docker, :container, :ls, "--all", "--filter", "name=^app-web-latest$", "--quiet", raise_on_non_zero_exit: false)
+      .returns("12345678") # running version
+
+    SSHKit::Backend::Abstract.any_instance.expects(:capture_with_info)
+      .with(:docker, :container, :ls, "--all", "--filter", "name=^app-web-latest$", "--quiet", "|", :xargs, :docker, :inspect, "--format", "'{{if .State.Health}}{{.State.Health.Status}}{{else}}{{.State.Status}}{{end}}'")
+      .returns("running") # health check
+
+    SSHKit::Backend::Abstract.any_instance.expects(:capture_with_info)
+      .with(:docker, :ps, "--filter", "label=service=app", "--filter", "label=role=web", "--filter", "status=running", "--filter", "status=restarting", "--latest", "--format", "\"{{.Names}}\"", "|", "while read line; do echo ${line#app-web-}; done", raise_on_non_zero_exit: false)
+      .returns("123") # old version
+
+    SSHKit::Backend::Abstract.any_instance.expects(:capture_with_info)
+      .with(:docker, :inspect, "-f '{{ range .Mounts }}{{printf \"%s %s\\n\" .Source .Destination}}{{ end }}'", "app-web-123", "|", :awk, "'$2 == \"/tmp/kamal-cord\" {print $1}'", raise_on_non_zero_exit: false)
+      .returns("cordfile") # old version
+
+    SSHKit::Backend::Abstract.any_instance.expects(:capture_with_info)
+      .with(:docker, :container, :ls, "--all", "--filter", "name=^app-web-123$", "--quiet", "|", :xargs, :docker, :inspect, "--format", "'{{if .State.Health}}{{.State.Health.Status}}{{else}}{{.State.Status}}{{end}}'")
+      .returns("unhealthy") # old version unhealthy
+
+    run_command("boot").tap do |output|
+      assert_match /Renaming container .* to .* as already deployed on 1.1.1.1/, output # Rename
+      assert_match /docker rename app-web-latest app-web-latest_replaced_[0-9a-f]{16}/, output
+      assert_match /docker run --detach --restart unless-stopped --name app-web-latest --hostname 1.1.1.1-[0-9a-f]{12} /, output
+      assert_match "docker container ls --all --filter name=^app-web-123$ --quiet | xargs docker stop", output
+    end
+  ensure
+    Thread.report_on_exception = true
+  end
+
+  test "boot uses group strategy when specified" do
+    Kamal::Cli::App.any_instance.stubs(:on).with("1.1.1.1").twice # acquire & release lock
+    Kamal::Cli::App.any_instance.stubs(:on).with([ "1.1.1.1" ]) # tag container
+
+    # Strategy is used when booting the containers
+    Kamal::Cli::App.any_instance.expects(:on).with([ "1.1.1.1" ], in: :groups, limit: 3, wait: 2).with_block_given
+
+    run_command("boot", config: :with_boot_strategy)
+  end
+
+  test "boot errors leave lock in place" do
+    Kamal::Cli::App.any_instance.expects(:using_version).raises(RuntimeError)
+
+    assert_not KAMAL.holding_lock?
+    assert_raises(RuntimeError) do
+      stderred { run_command("boot") }
+    end
+    assert KAMAL.holding_lock?
+  end
+
+  test "boot with assets" do
+    Object.any_instance.stubs(:sleep)
+    SSHKit::Backend::Abstract.any_instance.expects(:capture_with_info)
+      .with(:docker, :container, :ls, "--all", "--filter", "name=^app-web-latest$", "--quiet", raise_on_non_zero_exit: false)
+      .returns("12345678") # running version
+
+    SSHKit::Backend::Abstract.any_instance.expects(:capture_with_info)
+      .with(:docker, :container, :ls, "--all", "--filter", "name=^app-web-latest$", "--quiet", "|", :xargs, :docker, :inspect, "--format", "'{{if .State.Health}}{{.State.Health.Status}}{{else}}{{.State.Status}}{{end}}'")
+      .returns("running") # health check
+
+    SSHKit::Backend::Abstract.any_instance.expects(:capture_with_info)
+      .with(:docker, :ps, "--filter", "label=service=app", "--filter", "label=role=web", "--filter", "status=running", "--filter", "status=restarting", "--latest", "--format", "\"{{.Names}}\"", "|", "while read line; do echo ${line#app-web-}; done", raise_on_non_zero_exit: false)
+      .returns("123").twice # old version
+
+    SSHKit::Backend::Abstract.any_instance.expects(:capture_with_info)
+      .with(:docker, :inspect, "-f '{{ range .Mounts }}{{printf \"%s %s\\n\" .Source .Destination}}{{ end }}'", "app-web-123", "|", :awk, "'$2 == \"/tmp/kamal-cord\" {print $1}'", raise_on_non_zero_exit: false)
+      .returns("") # old version
+
+    run_command("boot", config: :with_assets).tap do |output|
+      assert_match "docker tag dhh/app:latest dhh/app:latest", output
+      assert_match "/usr/bin/env mkdir -p .kamal/assets/volumes/app-web-latest ; cp -rnT .kamal/assets/extracted/app-web-latest .kamal/assets/volumes/app-web-latest ; cp -rnT .kamal/assets/extracted/app-web-latest .kamal/assets/volumes/app-web-123 || true ; cp -rnT .kamal/assets/extracted/app-web-123 .kamal/assets/volumes/app-web-latest || true", output
+      assert_match "/usr/bin/env mkdir -p .kamal/assets/extracted/app-web-latest && docker stop -t 1 app-web-assets 2> /dev/null || true && docker run --name app-web-assets --detach --rm dhh/app:latest sleep 1000000 && docker cp -L app-web-assets:/public/assets/. .kamal/assets/extracted/app-web-latest && docker stop -t 1 app-web-assets", output
+      assert_match /docker run --detach --restart unless-stopped --name app-web-latest --hostname 1.1.1.1-[0-9a-f]{12} /, output
+      assert_match "docker container ls --all --filter name=^app-web-123$ --quiet | xargs docker stop", output
+      assert_match "/usr/bin/env find .kamal/assets/extracted -maxdepth 1 -name 'app-web-*' ! -name app-web-latest -exec rm -rf \"{}\" + ; find .kamal/assets/volumes -maxdepth 1 -name 'app-web-*' ! -name app-web-latest -exec rm -rf \"{}\" +", output
+    end
+  end
+
+  test "start" do
+    run_command("start").tap do |output|
+      assert_match "docker start app-web-999", output
+    end
+  end
+
+  test "stop" do
+    run_command("stop").tap do |output|
+      assert_match "docker ps --quiet --filter label=service=app --filter label=role=web --filter status=running --filter status=restarting --latest | xargs docker stop", output
+    end
+  end
+
+  test "stale_containers" do
+    SSHKit::Backend::Abstract.any_instance.expects(:capture_with_info)
+      .with(:docker, :ps, "--filter", "label=service=app", "--filter", "label=role=web", "--format", "\"{{.Names}}\"", "|", "while read line; do echo ${line#app-web-}; done", raise_on_non_zero_exit: false)
+      .returns("12345678\n87654321")
+
+    run_command("stale_containers").tap do |output|
+      assert_match /Detected stale container for role web with version 87654321/, output
+    end
+  end
+
+  test "stop stale_containers" do
+    SSHKit::Backend::Abstract.any_instance.expects(:capture_with_info)
+      .with(:docker, :ps, "--filter", "label=service=app", "--filter", "label=role=web", "--format", "\"{{.Names}}\"", "|", "while read line; do echo ${line#app-web-}; done", raise_on_non_zero_exit: false)
+      .returns("12345678\n87654321")
+
+    run_command("stale_containers", "--stop").tap do |output|
+      assert_match /Stopping stale container for role web with version 87654321/, output
+      assert_match /#{Regexp.escape("docker container ls --all --filter name=^app-web-87654321$ --quiet | xargs docker stop")}/, output
+    end
+  end
+
+  test "details" do
+    run_command("details").tap do |output|
+      assert_match "docker ps --filter label=service=app --filter label=role=web", output
+    end
+  end
+
+  test "remove" do
+    run_command("remove").tap do |output|
+      assert_match /#{Regexp.escape("docker ps --quiet --filter label=service=app --filter label=role=web --filter status=running --filter status=restarting --latest | xargs docker stop")}/, output
+      assert_match /#{Regexp.escape("docker container prune --force --filter label=service=app")}/, output
+      assert_match /#{Regexp.escape("docker image prune --all --force --filter label=service=app")}/, output
+    end
+  end
+
+  test "remove_container" do
+    run_command("remove_container", "1234567").tap do |output|
+      assert_match "docker container ls --all --filter name=^app-web-1234567$ --quiet | xargs docker container rm", output
+    end
+  end
+
+  test "remove_containers" do
+    run_command("remove_containers").tap do |output|
+      assert_match "docker container prune --force --filter label=service=app", output
+    end
+  end
+
+  test "remove_images" do
+    run_command("remove_images").tap do |output|
+      assert_match "docker image prune --all --force --filter label=service=app", output
+    end
+  end
+
+  test "exec" do
+    run_command("exec", "ruby -v").tap do |output|
+      assert_match "docker run --rm --env-file .kamal/env/roles/app-web.env dhh/app:latest ruby -v", output
+    end
+  end
+
+  test "exec with reuse" do
+    run_command("exec", "--reuse", "ruby -v").tap do |output|
+      assert_match "docker ps --filter label=service=app --filter label=role=web --filter status=running --filter status=restarting --latest --format \"{{.Names}}\" | while read line; do echo ${line#app-web-}; done", output # Get current version
+      assert_match "docker exec app-web-999 ruby -v", output
+    end
+  end
+
+  test "exec interactive" do
+    SSHKit::Backend::Abstract.any_instance.expects(:exec)
+      .with("ssh -t root@1.1.1.1 -p 22 'docker run -it --rm --env-file .kamal/env/roles/app-web.env dhh/app:latest ruby -v'")
+    run_command("exec", "-i", "ruby -v").tap do |output|
+      assert_match "Get most recent version available as an image...", output
+      assert_match "Launching interactive command with version latest via SSH from new container on 1.1.1.1...", output
+    end
+  end
+
+  test "exec interactive with reuse" do
+    SSHKit::Backend::Abstract.any_instance.expects(:exec)
+      .with("ssh -t root@1.1.1.1 -p 22 'docker exec -it app-web-999 ruby -v'")
+    run_command("exec", "-i", "--reuse", "ruby -v").tap do |output|
+      assert_match "Get current version of running container...", output
+      assert_match "Running docker ps --filter label=service=app --filter label=role=web --filter status=running --filter status=restarting --latest --format \"{{.Names}}\" | while read line; do echo ${line#app-web-}; done on 1.1.1.1", output
+      assert_match "Launching interactive command with version 999 via SSH from existing container on 1.1.1.1...", output
+    end
+  end
+
+  test "containers" do
+    run_command("containers").tap do |output|
+      assert_match "docker container ls --all --filter label=service=app", output
+    end
+  end
+
+  test "images" do
+    run_command("images").tap do |output|
+      assert_match "docker image ls dhh/app", output
+    end
+  end
+
+  test "logs" do
+    SSHKit::Backend::Abstract.any_instance.stubs(:exec)
+      .with("ssh -t root@1.1.1.1 'docker ps --quiet --filter label=service=app --filter label=role=web --filter status=running --filter status=restarting --latest| xargs docker logs --timestamps --tail 10 2>&1'")
+
+    assert_match "docker ps --quiet --filter label=service=app --filter label=role=web --filter status=running --filter status=restarting --latest | xargs docker logs --tail 100 2>&1", run_command("logs")
+  end
+
+  test "logs with follow" do
+    SSHKit::Backend::Abstract.any_instance.stubs(:exec)
+      .with("ssh -t root@1.1.1.1 -p 22 'docker ps --quiet --filter label=service=app --filter label=role=web --filter status=running --filter status=restarting --latest | xargs docker logs --timestamps --tail 10 --follow 2>&1'")
+
+    assert_match "docker ps --quiet --filter label=service=app --filter label=role=web --filter status=running --filter status=restarting --latest | xargs docker logs --timestamps --tail 10 --follow 2>&1", run_command("logs", "--follow")
+  end
+
+  test "version" do
+    run_command("version").tap do |output|
+      assert_match "docker ps --filter label=service=app --filter label=role=web --filter status=running --filter status=restarting --latest --format \"{{.Names}}\" | while read line; do echo ${line#app-web-}; done", output
+    end
+  end
+
+
+  test "version through main" do
+    stdouted { Kamal::Cli::Main.start([ "app", "version", "-c", "test/fixtures/deploy_with_accessories.yml", "--hosts", "1.1.1.1" ]) }.tap do |output|
+      assert_match "docker ps --filter label=service=app --filter label=role=web --filter status=running --filter status=restarting --latest --format \"{{.Names}}\" | while read line; do echo ${line#app-web-}; done", output
+    end
+  end
+
+  private
+    def run_command(*command, config: :with_accessories)
+      stdouted { Kamal::Cli::App.start([ *command, "-c", "test/fixtures/deploy_#{config}.yml", "--hosts", "1.1.1.1" ]) }
+    end
+
+    def stub_running
+      Object.any_instance.stubs(:sleep)
+
+      SSHKit::Backend::Abstract.any_instance.stubs(:capture_with_info).returns("123") # old version
+
+      SSHKit::Backend::Abstract.any_instance.expects(:capture_with_info)
+        .with(:docker, :container, :ls, "--all", "--filter", "name=^app-web-latest$", "--quiet", "|", :xargs, :docker, :inspect, "--format", "'{{if .State.Health}}{{.State.Health.Status}}{{else}}{{.State.Status}}{{end}}'")
+        .returns("running") # health check
+
+      SSHKit::Backend::Abstract.any_instance.expects(:capture_with_info)
+        .with(:docker, :container, :ls, "--all", "--filter", "name=^app-web-123$", "--quiet", "|", :xargs, :docker, :inspect, "--format", "'{{if .State.Health}}{{.State.Health.Status}}{{else}}{{.State.Status}}{{end}}'")
+        .returns("unhealthy") # health check
+    end
+end