From 6a3b0249fe8c07516992e850f43000a9a745cfdf Mon Sep 17 00:00:00 2001
From: Donal McBreen <donal@basecamp.com>
Date: Mon, 11 Sep 2023 17:02:32 +0100
Subject: [PATCH] Connect to remote host before creating builder

Connecting to the remote host will make any SSH configuration issues
obvious and add the host to known hosts if that is how SSHKit is
configured.
---
 lib/kamal/cli/build.rb                       | 14 +++++++
 test/cli/build_test.rb                       | 12 +++++-
 test/fixtures/deploy_with_remote_builder.yml | 41 ++++++++++++++++++++
 3 files changed, 65 insertions(+), 2 deletions(-)
 create mode 100644 test/fixtures/deploy_with_remote_builder.yml

diff --git a/lib/kamal/cli/build.rb b/lib/kamal/cli/build.rb
index 9a23117d..379fd12a 100644
--- a/lib/kamal/cli/build.rb
+++ b/lib/kamal/cli/build.rb
@@ -1,3 +1,5 @@
+require "uri"
+
 class Kamal::Cli::Build < Kamal::Cli::Base
   class BuildError < StandardError; end
 
@@ -55,6 +57,10 @@ class Kamal::Cli::Build < Kamal::Cli::Base
   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}"
@@ -103,4 +109,12 @@ class Kamal::Cli::Build < Kamal::Cli::Base
         end
       end
     end
+
+    def connect_to_remote_host(remote_host)
+      remote_uri = URI.parse(remote_host)
+      options = { user: remote_uri.user, port: remote_uri.port }.compact
+      on(remote_uri.host, options) do
+        execute "true"
+      end
+    end
 end
diff --git a/test/cli/build_test.rb b/test/cli/build_test.rb
index 35e8b761..c64a4917 100644
--- a/test/cli/build_test.rb
+++ b/test/cli/build_test.rb
@@ -66,6 +66,14 @@ class CliBuildTest < CliTestCase
     end
   end
 
+  test "create remote" do
+    run_command("create", fixture: :with_remote_builder).tap do |output|
+      assert_match "Running /usr/bin/env true on 1.1.1.5", output
+      assert_match "docker context create kamal-app-native-remote-amd64 --description 'kamal-app-native-remote amd64 native host' --docker 'host=ssh://app@1.1.1.5'", output
+      assert_match "docker buildx create --name kamal-app-native-remote kamal-app-native-remote-amd64 --platform linux/amd64", output
+    end
+  end
+
   test "create with error" do
     stub_setup
     SSHKit::Backend::Abstract.any_instance.stubs(:execute)
@@ -95,8 +103,8 @@ class CliBuildTest < CliTestCase
   end
 
   private
-    def run_command(*command)
-      stdouted { Kamal::Cli::Build.start([*command, "-c", "test/fixtures/deploy_with_accessories.yml"]) }
+    def run_command(*command, fixture: :with_accessories)
+      stdouted { Kamal::Cli::Build.start([*command, "-c", "test/fixtures/deploy_#{fixture}.yml"]) }
     end
 
     def stub_dependency_checks
diff --git a/test/fixtures/deploy_with_remote_builder.yml b/test/fixtures/deploy_with_remote_builder.yml
new file mode 100644
index 00000000..44103499
--- /dev/null
+++ b/test/fixtures/deploy_with_remote_builder.yml
@@ -0,0 +1,41 @@
+service: app
+image: dhh/app
+servers:
+  web:
+    - "1.1.1.1"
+    - "1.1.1.2"
+  workers:
+    - "1.1.1.3"
+    - "1.1.1.4"
+registry:
+  username: user
+  password: pw
+
+accessories:
+  mysql:
+    image: mysql:5.7
+    host: 1.1.1.3
+    port: 3306
+    env:
+      clear:
+        MYSQL_ROOT_HOST: '%'
+      secret:
+        - MYSQL_ROOT_PASSWORD
+    files:
+      - test/fixtures/files/my.cnf:/etc/mysql/my.cnf
+    directories:
+      - data:/var/lib/mysql
+  redis:
+    image: redis:latest
+    roles:
+      - web
+    port: 6379
+    directories:
+      - data:/data
+
+readiness_delay: 0
+
+builder:
+  remote:
+    arch: amd64
+    host: ssh://app@1.1.1.5