Allow overriding compose env for local builds

Now we can write this very simple pipeline for debugging builds locally.

```ruby
Buildkite::Builder.pipeline do
  require "buildkite_config"
  use Buildkite::Config::BuildContext
  use Buildkite::Config::DockerBuild
  use Buildkite::Config::RakeCommand
  use Buildkite::Config::RubyGroup

  plugin :docker_compose, "docker-compose#v4.16.0"
  plugin :artifacts, "artifacts#v1.9.3"

  build_context.setup_rubies %w(3.3)

  group do
    label "build"
    build_context.rubies.each do |ruby|
      builder ruby, compose: {
        "cli_version": "2",
        "image-name": "buildkite_base",
        "cache-from": ["buildkite_base"],
        "push": "",
        "image-repository": "",
      }
    end
  end

  build_context.rubies.each do |ruby|
    ruby_group ruby do
      rake "actioncable", task: "test:integration", retry_on: { exit_status: -1, limit: 3 }, compose: {
        "cli_version": "2",
        "pull": "",
      }, env: {
        "IMAGE_NAME": "buildkite_base",
      }
    end
  end
end
```

:nail_care: whitespace

lib/buildkite/config/docker_build.rb

@@ -43,12 +43,23 @@ def prepare
     end
 
     dsl do
-      def builder(ruby)
+      def builder(ruby, compose: nil)
         build_context = context.extensions.find(BuildContext)
         build_context.ruby = ruby
         return unless build_context.ruby.build?
 
         command do
+          compose_options = {
+            build: "base",
+            config: ".buildkite/docker-compose.yml",
+            env: %w[PRE_STEPS RACK],
+            "image-name" => build_context.ruby.image_name_for(build_context.build_id),
+            "cache-from" => cache_from(build_context),
+            push: build_push(build_context),
+            "image-repository" => build_context.image_base,
+          }
+          compose_options.merge!(compose) if compose
+
           label ":docker: #{build_context.ruby.prefix}#{build_context.ruby.version}"
           key "docker-image-#{build_context.ruby.image_key}"
           plugin :artifacts, {
@@ -66,16 +77,7 @@ def builder(ruby)
             compressed: ".buildkite.tgz"
           }
 
-          plugin :docker_compose, {
-            build: "base",
-            config: ".buildkite/docker-compose.yml",
-            env: %w[PRE_STEPS RACK],
-            "image-name" => build_context.ruby.image_name_for(build_context.build_id),
-            "cache-from" => cache_from(build_context),
-            push: build_push(build_context),
-            "image-repository" => build_context.image_base,
-          }
-
+          plugin :docker_compose, compose_options
           env({
             BUNDLER: build_context.bundler,
             RUBYGEMS: build_context.rubygems,

lib/buildkite/config/rake_command.rb

@@ -20,7 +20,7 @@ def build_env(build_context, pre_steps, env)
         env ||= {}
         pre_steps ||= []
 
-        env[:IMAGE_NAME] = build_context.image_name_for(build_context.build_id, prefix: nil)
+        env[:IMAGE_NAME] ||= build_context.image_name_for(build_context.build_id, prefix: nil)
 
         if build_context.ruby.yjit_enabled?
           env[:RUBY_YJIT_ENABLE] = "1"
@@ -33,7 +33,17 @@ def build_env(build_context, pre_steps, env)
         env
       end
 
-      def install_plugins(service = "default", env = nil, dir = ".")
+      def install_plugins(service = "default", env = nil, dir = ".", compose: nil)
+        compose_options = {
+          "env" => env,
+          "run" => service,
+          "pull" => service,
+          "pull-retries" => 3,
+          "config" => ".buildkite/docker-compose.yml",
+          "shell" => ["runner", *dir],
+        }
+        compose_options.merge!(compose) if compose
+
         plugin :artifacts, {
             download: ".dockerignore"
           }
@@ -49,14 +59,7 @@ def install_plugins(service = "default", env = nil, dir = ".")
           compressed: ".buildkite.tgz"
         }
 
-        plugin :docker_compose, {
-          "env" => env,
-          "run" => service,
-          "pull" => service,
-          "pull-retries" => 3,
-          "config" => ".buildkite/docker-compose.yml",
-          "shell" => ["runner", *dir],
-        }.compact
+        plugin :docker_compose, compose_options.compact
       end
     end
 
@@ -65,15 +68,15 @@ def prepare
     end
 
     dsl do
-      def bundle(command, label:, env: nil)
+      def bundle(command, label:, env: nil, compose: nil)
         build_context = context.extensions.find(BuildContext)
 
         command do
           label label
           depends_on "docker-image-#{build_context.ruby.image_key}"
           command command
 
-          install_plugins
+          install_plugins(compose: compose)
 
           env build_env(build_context, nil, env)
 
@@ -85,7 +88,7 @@ def bundle(command, label:, env: nil)
         end
       end
 
-      def rake(dir, task: "test", label: nil, service: "default", pre_steps: nil, env: nil, retry_on: nil, soft_fail: nil, parallelism: nil)
+      def rake(dir, task: "test", label: nil, service: "default", pre_steps: nil, env: nil, retry_on: nil, soft_fail: nil, parallelism: nil, compose: nil)
         build_context = context.extensions.find(BuildContext)
 
         if task.start_with?("mysql2:") || (build_context.rails_version >= Gem::Version.new("7.1.0.alpha") && task.start_with?("trilogy:"))
@@ -99,7 +102,7 @@ def rake(dir, task: "test", label: nil, service: "default", pre_steps: nil, env:
           depends_on "docker-image-#{build_context.ruby.image_key}"
           command "rake #{task}"
 
-          install_plugins(service,  %w[PRE_STEPS RACK], dir)
+          install_plugins(service, %w[PRE_STEPS RACK], dir, compose: compose)
 
           env build_env(build_context, pre_steps, env)
 

test/buildkite_config/test_docker_build.rb

@@ -153,4 +153,32 @@ def test_builder_gem_version
     assert_equal ["base:buildkite-config-base:ruby-1-9-3-br-main"], compose["cache-from"]
     assert_equal ["base:buildkite-config-base:ruby-1-9-3-br-"], compose["push"]
   end
+
+  def test_builder_compose_options
+    pipeline = PipelineFixture.new do
+      use Buildkite::Config::DockerBuild
+
+      build_context.stub(:rails_version, Gem::Version.new("7.1")) do
+        builder Buildkite::Config::RubyConfig.new(version: "3.2"), compose: {
+          "cli_version": "2",
+          "image-name": "buildkite_base",
+          "cache-from": ["buildkite_base"],
+          "push": "",
+          "image-repository": "",
+        }
+      end
+    end
+
+    plugins = pipeline.to_h["steps"][0]["plugins"]
+
+    compose = plugins.find { |plugin|
+      plugin.key?("docker-compose#v1.0")
+    }.fetch("docker-compose#v1.0")
+
+    assert_equal "2", compose["cli_version"]
+    assert_equal "buildkite_base", compose["image-name"]
+    assert_equal ["buildkite_base"], compose["cache-from"]
+    assert_equal "", compose["push"]
+    assert_equal "", compose["image-repository"]
+  end
 end

test/buildkite_config/test_rake_command.rb

@@ -147,6 +147,21 @@ def test_env
     assert_equal "buildkite-config-base:ruby-3-2-local", pipeline.to_h["steps"][0]["env"]["IMAGE_NAME"]
   end
 
+  def test_env_image_name
+    pipeline = PipelineFixture.new do
+      build_context.ruby = Buildkite::Config::RubyConfig.new(prefix: "ruby:", version: Gem::Version.new("3.2"))
+      use Buildkite::Config::RakeCommand
+
+      build_context.stub(:rails_version, Gem::Version.new("7.1")) do
+        rake "test", task: "test:all", env: { "IMAGE_NAME": "override-at-command-definition" }
+      end
+    end
+
+    assert_includes pipeline.to_h["steps"][0], "env"
+    assert_includes pipeline.to_h["steps"][0]["env"], "IMAGE_NAME"
+    assert_equal "override-at-command-definition", pipeline.to_h["steps"][0]["env"]["IMAGE_NAME"]
+  end
+
   def test_timeout_in_minutes
     pipeline = PipelineFixture.new do
       build_context.ruby = Buildkite::Config::RubyConfig.new(prefix: "ruby:", version: Gem::Version.new("3.2"))
@@ -220,6 +235,39 @@ def test_compose
     assert_equal ["runner", "test"], compose["shell"]
   end
 
+  def test_compose_options
+    pipeline = PipelineFixture.new do
+      build_context.ruby = Buildkite::Config::RubyConfig.new(prefix: "ruby:", version: Gem::Version.new("3.2"))
+      use Buildkite::Config::RakeCommand
+
+      build_context.stub(:rails_version, Gem::Version.new("7.1")) do
+        rake "test", task: "test:all", compose: {
+          "cli_version": "2",
+          "pull": "",
+        }
+      end
+    end
+
+    plugins = pipeline.to_h["steps"][0]["plugins"]
+
+    compose = plugins.find { |plugin|
+      plugin.key?("docker-compose#v1.0")
+    }.fetch("docker-compose#v1.0")
+
+    %w[env run pull config shell].each do |key|
+      assert_includes compose, key
+    end
+
+    assert_includes compose["env"], "PRE_STEPS"
+    assert_includes compose["env"], "RACK"
+
+    assert_equal "2", compose["cli_version"]
+    assert_equal "default", compose["run"]
+    assert_equal "", compose["pull"]
+    assert_equal ".buildkite/docker-compose.yml", compose["config"]
+    assert_equal ["runner", "test"], compose["shell"]
+  end
+
   def test_multiple
     pipeline = PipelineFixture.new do
       build_context.ruby = Buildkite::Config::RubyConfig.new(version: Gem::Version.new("3.2"))
@@ -462,4 +510,41 @@ def test_bundle_command
     assert_equal ["test-reports/*/*.xml"], step["artifact_paths"]
     assert_equal 30, step["timeout_in_minutes"]
   end
+
+  def test_bundle_command_options
+    pipeline = PipelineFixture.new do
+      build_context.ruby = Buildkite::Config::RubyConfig.new(prefix: "ruby:", version: Gem::Version.new("3.2"))
+      use Buildkite::Config::RakeCommand
+
+      build_context.stub(:rails_version, Gem::Version.new("7.1")) do
+        bundle "rubocop", label: "rubocop", compose: {
+          "cli_version": "2",
+          "pull": "",
+        }, env: {
+          "IMAGE_NAME": "override-at-command-definition",
+        }
+      end
+    end
+
+    step = pipeline.to_h["steps"][0]
+    assert_equal "override-at-command-definition", step["env"]["IMAGE_NAME"]
+
+    plugins = step["plugins"]
+
+    compose = plugins.find { |plugin|
+      plugin.key?("docker-compose#v1.0")
+    }.fetch("docker-compose#v1.0")
+
+    %w[run pull config shell].each do |key|
+      assert_includes compose, key
+    end
+
+    assert_predicate compose["env"], :nil?
+
+    assert_equal "2", compose["cli_version"]
+    assert_equal "default", compose["run"]
+    assert_equal "", compose["pull"]
+    assert_equal ".buildkite/docker-compose.yml", compose["config"]
+    assert_equal ["runner", "."], compose["shell"]
+  end
 end