Extract Dev Container implementation into its own generator

This refactoring prepares the way to implement a devcontainer command to add an devcontainer to an existing app.

Author: andrewn617

railties/lib/rails/generators/app_base.rb

@@ -12,7 +12,6 @@
 module Rails
   module Generators
     class AppBase < Base # :nodoc:
-      include Devcontainer
       include AppName
 
       NODE_LTS_VERSION = "20.11.1"
@@ -454,10 +453,6 @@ def to_s
         end
       end
 
-      def gem_ruby_version
-        Gem::Version.new(Gem::VERSION) >= Gem::Version.new("3.3.13") ? Gem.ruby_version : RUBY_VERSION
-      end
-
       def rails_prerelease?
         options.dev? || options.edge? || options.main?
       end

railties/lib/rails/generators/base.rb

@@ -423,6 +423,10 @@ def self.default_generator_root # :doc:
           path = File.expand_path(File.join(base_name, generator_name), base_root)
           path if File.exist?(path)
         end
+
+        def gem_ruby_version
+          Gem::Version.new(Gem::VERSION) >= Gem::Version.new("3.3.13") ? Gem.ruby_version : RUBY_VERSION
+        end
     end
   end
 end

railties/lib/rails/generators/devcontainer.rb

@@ -1,6 +1,7 @@
 # frozen_string_literal: true
 
 require "rails/generators/app_base"
+require "rails/generators/rails/devcontainer/devcontainer_generator"
 
 module Rails
   module ActionMethods # :nodoc:
@@ -268,11 +269,17 @@ def config_target_version
     end
 
     def devcontainer
-      empty_directory ".devcontainer"
-
-      template ".devcontainer/devcontainer.json"
-      template ".devcontainer/Dockerfile"
-      template ".devcontainer/compose.yaml"
+      devcontainer_options = {
+        database: options[:database],
+        redis: !(options[:skip_action_cable] && options[:skip_active_job]),
+        system_test: depends_on_system_test?,
+        active_storage: !options[:skip_active_storage],
+        dev: options[:dev],
+        node: using_node?,
+        app_name: app_name
+      }
+
+      Rails::Generators::DevcontainerGenerator.new([], devcontainer_options).invoke_all
     end
   end
 

railties/lib/rails/generators/rails/app/app_generator.rb

@@ -0,0 +1,127 @@
+# frozen_string_literal: true
+
+require "rails/generators"
+
+module Rails
+  module Generators
+    class DevcontainerGenerator < Base # :nodoc:
+      class_option :app_name, type: :string, default: "rails_app",
+                   desc: "Name of the app"
+
+      class_option :database, enum: Database::DATABASES, type: :string, default: "sqlite3",
+                   desc: "Include configuration for selected database"
+
+      class_option :redis, type: :boolean, default: true,
+                   desc: "Include configuration for Redis"
+
+      class_option :system_test, type: :boolean, default: true,
+                   desc: "Include configuration for System Tests"
+
+      class_option :active_storage, type: :boolean, default: true,
+                   desc: "Include configuration for Active Storage"
+
+      class_option :node, type: :boolean, default: false,
+                   desc: "Include configuration for Node"
+
+      class_option :dev, type: :boolean, default: false,
+                    desc: "For applications pointing to a local Rails checkout"
+
+      def create_devcontainer
+        empty_directory ".devcontainer"
+
+        template ".devcontainer/devcontainer.json"
+        template ".devcontainer/Dockerfile"
+        template ".devcontainer/compose.yaml"
+      end
+
+      private
+        def dependencies
+          return @dependencies if @dependencies
+
+          @dependencies = []
+
+          @dependencies << "selenium" if options[:system_test]
+          @dependencies << "redis" if options[:redis]
+          @dependencies << database.name if database.service
+          @dependencies
+        end
+
+        def container_env
+          return @container_env if @container_env
+
+          @container_env = {}
+
+          @container_env["CAPYBARA_SERVER_PORT"] = "45678" if options[:system_test]
+          @container_env["SELENIUM_HOST"] = "selenium" if options[:system_test]
+          @container_env["REDIS_URL"] = "redis://redis:6379/1" if options[:redis]
+          @container_env["DB_HOST"] = database.name if database.service
+
+          @container_env
+        end
+
+        def volumes
+          return @volumes if @volumes
+
+          @volumes = []
+
+          @volumes << "redis-data" if options[:redis]
+          @volumes << database.volume if database.volume
+
+          @volumes
+        end
+
+        def features
+          return @features if @features
+
+          @features = {
+            "ghcr.io/devcontainers/features/github-cli:1" => {}
+          }
+
+          @features["ghcr.io/rails/devcontainer/features/activestorage"] = {} if options[:active_storage]
+          @features["ghcr.io/devcontainers/features/node:1"] = {} if options[:node]
+
+          @features.merge!(database.feature) if database.feature
+
+          @features
+        end
+
+        def mounts
+          return @mounts if @mounts
+
+          @mounts = []
+
+          @mounts << local_rails_mount if options[:dev]
+
+          @mounts
+        end
+
+        def forward_ports
+          return @forward_ports if @forward_ports
+
+          @forward_ports = [3000]
+          @forward_ports << database.port if database.port
+          @forward_ports << 6379 if options[:redis]
+
+          @forward_ports
+        end
+
+        def database
+          @database ||= Database.build(options[:database])
+        end
+
+        def devcontainer_db_service_yaml(**options)
+          return unless service = database.service
+
+          { database.name => service }.to_yaml(**options)[4..-1]
+        end
+
+        def local_rails_mount
+          {
+            type: "bind",
+            source: Rails::Generators::RAILS_DEV_PATH,
+            target: Rails::Generators::RAILS_DEV_PATH
+          }
+        end
+    end
+  end
+end

railties/lib/rails/generators/rails/devcontainer/devcontainer_generator.rb

@@ -1,4 +1,4 @@
-name: "<%= app_name %>"
+name: "<%= options[:app_name] %>"
 
 services:
   rails-app:
@@ -22,13 +22,13 @@ services:
     # (Adding the "ports" property to this file will not forward from a Codespace.)
     ports:
     - 45678:45678
-<%- if !devcontainer_dependencies.empty? -%>
+<%- if !dependencies.empty? -%>
     depends_on:
-<%- devcontainer_dependencies.each do |dependency| -%>
+<%- dependencies.each do |dependency| -%>
     - <%= dependency %>
 <%- end -%>
 <%- end -%>
-<%- if depends_on_system_test? -%>
+<%- if options[:system_test] -%>
 
   selenium:
     image: seleniarm/standalone-chromium
@@ -37,7 +37,7 @@ services:
     - default
 <%- end -%>
 
-<%- if devcontainer_needs_redis? -%>
+<%- if options[:redis] -%>
   redis:
     image: redis:7.2
     restart: unless-stopped
@@ -48,9 +48,9 @@ services:
 
 <%- end -%>
   <%= devcontainer_db_service_yaml(indentation: 4) %>
-<%- if !devcontainer_volumes.empty? -%>
+<%- if !volumes.empty? -%>
 volumes:
-<%- devcontainer_volumes.each do |volume| -%>
+<%- volumes.each do |volume| -%>
   <%= volume %>:
 <%- end -%>
 <%- end -%>

railties/lib/rails/generators/rails/app/templates/.devcontainer/Dockerfile.tt renamed to railties/lib/rails/generators/rails/devcontainer/templates/.devcontainer/Dockerfile.tt

@@ -1,34 +1,34 @@
 // For format details, see https://aka.ms/devcontainer.json. For config options, see the
 // README at: https://github.com/devcontainers/templates/tree/main/src/ruby
 {
-  "name": "<%= app_name %>",
+  "name": "<%= options[:app_name] %>",
   "dockerComposeFile": "compose.yaml",
   "service": "rails-app",
   "workspaceFolder": "/workspaces/${localWorkspaceFolderBasename}",
 
   // Features to add to the dev container. More info: https://containers.dev/features.
   "features": {
-    <%= devcontainer_features.map { |key, value| "\"#{key}\": #{value.as_json}" }.join(",\n    ") %>
+    <%= features.map { |key, value| "\"#{key}\": #{value.as_json}" }.join(",\n    ") %>
   },
 
-<%- if !devcontainer_variables.empty? -%>
+<%- if !container_env.empty? -%>
   "containerEnv": {
-    <%= devcontainer_variables.map { |key, value| "\"#{key}\": \"#{value}\"" }.join(",\n    ") %>
+    <%= container_env.map { |key, value| "\"#{key}\": \"#{value}\"" }.join(",\n    ") %>
   },
 <%- end -%>
 
   // Use 'forwardPorts' to make a list of ports inside the container available locally.
-  "forwardPorts": <%= devcontainer_forward_ports.as_json %>,
+  "forwardPorts": <%= forward_ports.as_json %>,
 
   // Configure tool-specific properties.
   // "customizations": {},
 
   // Uncomment to connect as root instead. More info: https://aka.ms/dev-containers-non-root.
   // "remoteUser": "root",
 
-<%- if !devcontainer_mounts.empty? -%>
+<%- if !mounts.empty? -%>
   "mounts": [
-    <%= devcontainer_mounts.map { |mount| "{\n      " + mount.map { |key, value| "\"#{key}\": \"#{value}\"" }.join(",\n      ") + "\n    }" }.join(",\n    ") %>
+    <%= mounts.map { |mount| "{\n      " + mount.map { |key, value| "\"#{key}\": \"#{value}\"" }.join(",\n      ") + "\n    }" }.join(",\n    ") %>
   ],
 <%- end -%>