From 9a84460754cf771532935dc0728615a6424253e7 Mon Sep 17 00:00:00 2001
From: David Heinemeier Hansson <david@loudthinking.com>
Date: Tue, 17 Jan 2023 13:35:55 +0100
Subject: [PATCH] Add option for two-part configs with the destination option

---
 lib/mrsk/cli.rb                         |  6 +++---
 lib/mrsk/cli/base.rb                    | 13 +++++++++++-
 lib/mrsk/commander.rb                   |  9 ++++-----
 lib/mrsk/configuration.rb               | 27 +++++++++++++++++++------
 test/configuration_test.rb              | 20 +++++++++++++++++-
 test/fixtures/deploy_for_dest.mars.yml  |  5 +++++
 test/fixtures/deploy_for_dest.world.yml |  5 +++++
 test/fixtures/deploy_for_dest.yml       |  6 ++++++
 8 files changed, 75 insertions(+), 16 deletions(-)
 create mode 100644 test/fixtures/deploy_for_dest.mars.yml
 create mode 100644 test/fixtures/deploy_for_dest.world.yml
 create mode 100644 test/fixtures/deploy_for_dest.yml

diff --git a/lib/mrsk/cli.rb b/lib/mrsk/cli.rb
index 5413e350..35fc8f44 100644
--- a/lib/mrsk/cli.rb
+++ b/lib/mrsk/cli.rb
@@ -1,9 +1,9 @@
 require "mrsk"
 
-MRSK = Mrsk::Commander.new \
-  config_file: Pathname.new(File.expand_path("config/deploy.yml"))
-
 module Mrsk::Cli
 end
 
+# SSHKit uses instance eval, so we need a global const for ergonomics
+MRSK = Mrsk::Commander.new
+
 require "mrsk/cli/main"
diff --git a/lib/mrsk/cli/base.rb b/lib/mrsk/cli/base.rb
index a2821915..87ffbafb 100644
--- a/lib/mrsk/cli/base.rb
+++ b/lib/mrsk/cli/base.rb
@@ -10,12 +10,23 @@ module Mrsk::Cli
 
     class_option :verbose, type: :boolean, aliases: "-v", desc: "Detailed logging"
 
+    class_option :config_file, aliases: "-c", default: "config/deploy.yml", desc: "Path to config file (default: config/deploy.yml)"
+    class_option :destination, aliases: "-d", desc: "Specify destination to be used for config file (west -> deploy.west.yml)"
+
     def initialize(*)
       super
-      MRSK.verbose = options[:verbose]
+      initialize_commander(options)
     end
 
     private
+      def initialize_commander(options)
+        MRSK.tap do |commander|
+          commander.config_file = Pathname.new(File.expand_path(options[:config_file]))
+          commander.destination = options[:destination]
+          commander.verbose     = options[:verbose]
+        end
+      end
+
       def print_runtime
         started_at = Time.now
         yield
diff --git a/lib/mrsk/commander.rb b/lib/mrsk/commander.rb
index 26c87b5d..10e15b1d 100644
--- a/lib/mrsk/commander.rb
+++ b/lib/mrsk/commander.rb
@@ -6,15 +6,14 @@ require "mrsk/commands/traefik"
 require "mrsk/commands/registry"
 
 class Mrsk::Commander
-  attr_reader :config
-  attr_accessor :verbose
+  attr_accessor :config_file, :destination, :verbose
 
-  def initialize(config_file:)
-    @config_file = config_file
+  def initialize(config_file: nil, destination: nil, verbose: false)
+    @config_file, @destination, @verbose = config_file, destination, verbose
   end
 
   def config
-    @config ||= Mrsk::Configuration.load_file(@config_file).tap { |config| setup_with(config) }
+    @config ||= Mrsk::Configuration.create_from(config_file, destination: destination).tap { |config| setup_with(config) }
   end
 
 
diff --git a/lib/mrsk/configuration.rb b/lib/mrsk/configuration.rb
index 0920d276..b8a23826 100644
--- a/lib/mrsk/configuration.rb
+++ b/lib/mrsk/configuration.rb
@@ -9,17 +9,32 @@ class Mrsk::Configuration
   delegate :service, :image, :servers, :env, :labels, :registry, :builder, to: :config, allow_nil: true
 
   class << self
-    def load_file(file)
-      if file.exist?
-        new YAML.load(ERB.new(IO.read(file)).result).symbolize_keys
-      else
-        raise "Configuration file not found in #{file}"
-      end
+    def create_from(base_config_file, destination: nil)
+      new(load_config_file(base_config_file).tap do |config|
+        if destination
+          config.merge! \
+            load_config_file destination_config_file(base_config_file, destination)
+        end
+      end)
     end
 
     def argumentize(argument, attributes, redacted: false)
       attributes.flat_map { |k, v| [ argument, redacted ? Mrsk::Utils.redact("#{k}=#{v}") : "#{k}=#{v}" ] }
     end
+
+    private
+      def load_config_file(file)
+        if file.exist?
+          YAML.load(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)
+        dir, basename = base_config_file.split
+        dir.join basename.to_s.remove(".yml") + ".#{destination}.yml"
+      end
   end
 
   def initialize(config, validate: true)
diff --git a/test/configuration_test.rb b/test/configuration_test.rb
index 406e9fbc..9170c67e 100644
--- a/test/configuration_test.rb
+++ b/test/configuration_test.rb
@@ -111,7 +111,25 @@ class ConfigurationTest < ActiveSupport::TestCase
 
 
   test "erb evaluation of yml config" do
-    config = Mrsk::Configuration.load_file Pathname.new(File.expand_path("fixtures/deploy.erb.yml", __dir__))
+    config = Mrsk::Configuration.create_from Pathname.new(File.expand_path("fixtures/deploy.erb.yml", __dir__))
     assert_equal "my-user", config.registry["username"]
   end
+
+  test "destination yml config merge" do
+    dest_config_file = Pathname.new(File.expand_path("fixtures/deploy_for_dest.yml", __dir__))
+
+    config = Mrsk::Configuration.create_from dest_config_file, destination: "world"
+    assert_equal "1.1.1.1", config.hosts.first
+
+    config = Mrsk::Configuration.create_from dest_config_file, destination: "mars"
+    assert_equal "1.1.1.3", config.hosts.first
+  end
+
+  test "destination yml config file missing" do
+    dest_config_file = Pathname.new(File.expand_path("fixtures/deploy_for_dest.yml", __dir__))
+
+    assert_raises(RuntimeError) do
+      config = Mrsk::Configuration.create_from dest_config_file, destination: "missing"
+    end
+  end
 end
diff --git a/test/fixtures/deploy_for_dest.mars.yml b/test/fixtures/deploy_for_dest.mars.yml
new file mode 100644
index 00000000..c4fb213a
--- /dev/null
+++ b/test/fixtures/deploy_for_dest.mars.yml
@@ -0,0 +1,5 @@
+servers:
+  - 1.1.1.3
+  - 1.1.1.4
+env:
+  REDIS_URL: redis://a/b
diff --git a/test/fixtures/deploy_for_dest.world.yml b/test/fixtures/deploy_for_dest.world.yml
new file mode 100644
index 00000000..764dd236
--- /dev/null
+++ b/test/fixtures/deploy_for_dest.world.yml
@@ -0,0 +1,5 @@
+servers:
+  - 1.1.1.1
+  - 1.1.1.2
+env:
+  REDIS_URL: redis://x/y
diff --git a/test/fixtures/deploy_for_dest.yml b/test/fixtures/deploy_for_dest.yml
new file mode 100644
index 00000000..96740aec
--- /dev/null
+++ b/test/fixtures/deploy_for_dest.yml
@@ -0,0 +1,6 @@
+service: app
+image: dhh/app
+registry:
+  server: registry.digitalocean.com
+  username: <%= "my-user" %>
+  password: <%= "my-password" %>