Generate a .devcontainer folder and its contents when creating a new …

…app.

The devcontainer folder includes everything needed to boot the app and do development in a remote container.

The container setup includes:
 - A redis container for Sidekiq and Action Cable
 - A database (SQLite, Postgres, MySQL or MariaDB)
 - A Headless chrome container for system tests
 - Active Storage configured to use the local disk and with preview features working

If any of these options are skipped in the app setup they will not be included in the container configuration.

Co-authored-by: Rafael Mendonça França <rafael@franca.dev>

railties/CHANGELOG.md

@@ -1,3 +1,19 @@
+*   Generate a .devcontainer folder and its contents when creating a new app.
+
+    The .devcontainer folder includes everything needed to boot the app and do development in a remote container.
+
+    The container setup includes:
+     - A redis container for Sidekiq and Action Cable
+     - A database (SQLite, Postgres, MySQL or MariaDB)
+     - A Headless chrome container for system tests
+     - Active Storage configured to use the local disk and with preview features working
+
+    If any of these options are skipped in the app setup they will not be included in the container configuration.
+
+    These files can be skipped using the `--skip_devcontainer` option.
+
+    *Andrew Novoselac & Rafael Mendonça França*
+
 *   Rails console now indicates application name and the current Rails environment:
 
     ```txt

railties/lib/rails/generators/app_base.rb

@@ -109,6 +109,9 @@ def self.add_shared_options_for(name)
         class_option :skip_ci,             type: :boolean, default: nil,
                                            desc: "Skip GitHub CI files"
 
+        class_option :skip_devcontainer,   type: :boolean, default: nil,
+                                           desc: "Skip devcontainer files"
+
         class_option :dev,                 type: :boolean, default: nil,
                                            desc: "Set up the #{name} with Gemfile pointing to your Rails checkout"
 
@@ -400,6 +403,10 @@ def skip_ci?
         options[:skip_ci]
       end
 
+      def skip_devcontainer?
+        options[:skip_devcontainer]
+      end
+
       class GemfileEntry < Struct.new(:name, :version, :comment, :options, :commented_out)
         def initialize(name, version, comment, options = {}, commented_out = false)
           super

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

@@ -268,6 +268,14 @@ def vendor
     def config_target_version
       @config_target_version || Rails::VERSION::STRING.to_f
     end
+
+    def devcontainer
+      empty_directory ".devcontainer"
+
+      template ".devcontainer/devcontainer.json"
+      template ".devcontainer/Dockerfile"
+      template ".devcontainer/docker-compose.yml"
+    end
   end
 
   module Generators
@@ -457,6 +465,11 @@ def create_storage_files
         build(:storage)
       end
 
+      def create_devcontainer_files
+        return if skip_devcontainer?
+        build(:devcontainer)
+      end
+
       def delete_app_assets_if_api_option
         if options[:api]
           remove_dir "app/assets"
@@ -595,6 +608,20 @@ def after_bundle(&block) # :doc:
       def get_builder_class
         defined?(::AppBuilder) ? ::AppBuilder : Rails::AppBuilder
       end
+
+      def devcontainer_dependencies
+        return @devcontainer_dependencies if @devcontainer_dependencies
+
+        @devcontainer_dependencies = []
+
+        @devcontainer_dependencies << "selenium" if depends_on_system_test?
+        @devcontainer_dependencies << "redis" unless options.skip_action_cable? && options.skip_active_job?
+        @devcontainer_dependencies << "postgres" if options.database == "postgresql"
+        @devcontainer_dependencies << "mysql" if options.database == "mysql"
+        @devcontainer_dependencies << "mariadb" if options.database == "trilogy"
+
+        @devcontainer_dependencies
+      end
     end
 
     # This class handles preparation of the arguments before the AppGenerator is

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

@@ -0,0 +1,14 @@
+FROM mcr.microsoft.com/devcontainers/ruby:1-3-bookworm
+
+<%- unless options.skip_active_storage -%>
+# Install packages needed to build gems
+RUN apt-get update -qq && \
+    apt-get install --no-install-recommends -y \
+      libvips \
+      #  For video thumbnails
+      ffmpeg \
+      # For pdf thumbnails. If you want to use mupdf instead of poppler,
+      # you can install the following packages instead:
+      # mupdf mupdf-tools
+      poppler-utils
+<%- end -%>

railties/lib/rails/generators/rails/app/templates/.devcontainer/devcontainer.json.tt

@@ -0,0 +1,49 @@
+// 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": "Ruby",
+  "dockerComposeFile": "docker-compose.yml",
+  "service": "rails-app",
+  "workspaceFolder": "/workspaces/${localWorkspaceFolderBasename}",
+
+  // Features to add to the dev container. More info: https://containers.dev/features.
+  "features": {
+    "ghcr.io/devcontainers/features/github-cli:1": {}
+  },
+
+  "containerEnv": {
+<%- if depends_on_system_test? -%>
+    "CAPYBARA_SERVER_PORT": "45678",
+<%- end -%>
+<%- unless options.skip_active_job? -%>
+    "JOBS_REDIS_URL": "redis://redis:6379/1",
+<%- end -%>
+<%- unless options.skip_action_cable? -%>
+    "CABLE_REDIS_URL": "redis://redis:6379/1",
+<%- end -%>
+<%- if options.database == "postgresql" -%>
+    "RAILS_DATABASE_HOST": "postgres",
+<%- end -%>
+<%- if options.database == "mysql" -%>
+    "RAILS_DATABASE_HOST": "mysql",
+<%- end -%>
+<%- if options.database == "trilogy" -%>
+    "RAILS_DATABASE_HOST": "mariadb",
+<%- end -%>
+  },
+
+  // Features to add to the dev container. More info: https://containers.dev/features.
+  // "features": {},
+
+  // Use 'forwardPorts' to make a list of ports inside the container available locally.
+  // "forwardPorts": [],
+
+  // Use 'postCreateCommand' to run commands after the container is created.
+  "postCreateCommand": "bin/setup"
+
+  // Configure tool-specific properties.
+  // "customizations": {},
+
+  // Uncomment to connect as root instead. More info: https://aka.ms/dev-containers-non-root.
+  // "remoteUser": "root"
+}

railties/lib/rails/generators/rails/app/templates/.devcontainer/docker-compose.yml.tt

@@ -0,0 +1,78 @@
+services:
+  rails-app:
+    build:
+      context: ..
+      dockerfile: .devcontainer/Dockerfile
+
+    volumes:
+      - ../..:/workspaces:cached
+
+    # Overrides default command so things don't shut down after the process ends.
+    command: sleep infinity
+
+    networks:
+      - default
+
+    # Uncomment the next line to use a non-root user for all processes.
+    # user: vscode
+
+    # Use "forwardPorts" in **devcontainer.json** to forward an app port locally.
+    # (Adding the "ports" property to this file will not forward from a Codespace.)
+    ports:
+      - 45678:45678
+<%- if !devcontainer_dependencies.empty? -%>
+    depends_on:
+<%- devcontainer_dependencies.each do |dependency| -%>
+      - <%= dependency %>
+<%- end -%>
+<%- end -%>
+
+<%- if depends_on_system_test? -%>
+  selenium:
+    image: seleniarm/standalone-chromium
+    restart: unless-stopped
+    networks:
+      - default
+<%- end -%>
+
+<%- unless options.skip_active_job? && options.skip_action_cable? -%>
+  redis:
+    image: redis:7.2
+    restart: unless-stopped
+    networks:
+      - default
+    ports:
+      - 6379:6379
+<%- end -%>
+
+<%- if options.database == "postgresql" -%>
+  postgres:
+    image: postgres:16.1
+    restart: unless-stopped
+    networks:
+      - default
+    environment:
+      POSTGRES_USER: postgres
+      POSTGRES_PASSWORD: postgres
+<%- end -%>
+
+<%- if options.database == "mysql" -%>
+  mysql:
+    image: mysql/mysql-server:8.0
+    restart: unless-stopped
+    environment:
+      MYSQL_ALLOW_EMPTY_PASSWORD: true
+      MYSQL_ROOT_HOST: "%"
+    networks:
+      - default
+<%- end -%>
+
+<%- if options.database == "trilogy" -%>
+  mariadb:
+    image: mariadb:10.5
+    restart: unless-stopped
+    networks:
+      - default
+    environment:
+      MARIADB_ALLOW_EMPTY_ROOT_PASSWORD: true
+<%- end -%>

railties/test/generators/app_generator_test.rb

@@ -1253,6 +1253,133 @@ def test_name_option
     assert_file "config/application.rb", /^module MyApp$/
   end
 
+  def test_devcontainer
+    run_generator
+
+    assert_file(".devcontainer/devcontainer.json") do |content|
+      assert_match(/JOBS_REDIS_URL/, content)
+      assert_match(/CABLE_REDIS_URL/, content)
+      assert_match(/CAPYBARA_SERVER_PORT/, content)
+    end
+    assert_file(".devcontainer/Dockerfile") do |content|
+      assert_match(/libvips/, content)
+      assert_match(/ffmpeg/, content)
+      assert_match(/poppler-utils/, content)
+    end
+    assert_file(".devcontainer/docker-compose.yml") do |content|
+      assert_match(/depends_on:/, content)
+      assert_match(/- selenium/, content)
+      assert_match(/selenium:/, content)
+      assert_match(/redis:/, content)
+      assert_match(/- redis/, content)
+      assert_no_match(/- maria_db/, content)
+      assert_no_match(/maria_db:/, content)
+      assert_no_match(/- postgres/, content)
+      assert_no_match(/postgres:/, content)
+      assert_no_match(/- mysql/, content)
+      assert_no_match(/mysql:/, content)
+    end
+  end
+
+  def test_devcontainer_no_redis_skipping_action_cable_and_active_job
+    run_generator [ destination_root, "--skip_action_cable", "--skip_active_job" ]
+
+    assert_file(".devcontainer/docker-compose.yml") do |content|
+      assert_no_match(/- redis/, content)
+      assert_no_match(/redis:/, content)
+    end
+  end
+
+  def test_devcontainer_no_jobs_redis_url_when_skipping_active_job
+    run_generator [ destination_root, "--skip_active_job" ]
+
+    assert_file(".devcontainer/devcontainer.json") do |content|
+      assert_no_match(/JOBS_REDIS_URL/, content)
+    end
+  end
+
+  def test_devcontainer_no_cable_redis_url_when_skipping_action_cable
+    run_generator [ destination_root, "--skip_action_cable" ]
+
+    assert_file(".devcontainer/devcontainer.json") do |content|
+      assert_no_match(/CABLE_REDIS_URL/, content)
+    end
+  end
+
+  def test_devonctainer_postgresql
+    run_generator [ destination_root, "-d", "postgresql" ]
+
+    assert_file(".devcontainer/docker-compose.yml") do |content|
+      assert_match(/- postgres/, content)
+      assert_match(/postgres:/, content)
+    end
+    assert_file(".devcontainer/devcontainer.json") do |content|
+      assert_match(/"RAILS_DATABASE_HOST": "postgres"/, content)
+    end
+  end
+
+  def test_devonctainer_mysql
+    run_generator [ destination_root, "-d", "mysql" ]
+
+    assert_file(".devcontainer/docker-compose.yml") do |content|
+      assert_match(/- mysql/, content)
+      assert_match(/mysql:/, content)
+    end
+    assert_file(".devcontainer/devcontainer.json") do |content|
+      assert_match(/"RAILS_DATABASE_HOST": "mysql"/, content)
+    end
+  end
+
+  def test_devonctainer_mariadb
+    run_generator [ destination_root, "-d", "trilogy" ]
+
+    assert_file(".devcontainer/docker-compose.yml") do |content|
+      assert_match(/- mariadb/, content)
+      assert_match(/mariadb:/, content)
+    end
+    assert_file(".devcontainer/devcontainer.json") do |content|
+      assert_match(/"RAILS_DATABASE_HOST": "mariadb"/, content)
+    end
+  end
+
+  def test_devcontainer_no_selenium_when_skipping_system_test
+    run_generator [ destination_root, "--skip_system_test" ]
+
+    assert_file(".devcontainer/docker-compose.yml") do |content|
+      assert_no_match(/- selenium/, content)
+      assert_no_match(/selenium:/, content)
+    end
+    assert_file(".devcontainer/devcontainer.json") do |content|
+      assert_no_match(/CAPYBARA_SERVER_PORT/, content)
+    end
+  end
+
+  def test_devcontainer_no_Dockerfile_packages_when_skipping_active_storage
+    run_generator [ destination_root, "--skip_active_storage" ]
+
+    assert_file(".devcontainer/Dockerfile") do |content|
+      assert_no_match(/libvips/, content)
+      assert_no_match(/ffmpeg/, content)
+      assert_no_match(/poppler-utils/, content)
+    end
+  end
+
+  def test_devcontainer_no_depends_on_when_no_dependencies
+    run_generator [ destination_root, "--minimal" ]
+
+    assert_file(".devcontainer/docker-compose.yml") do |content|
+      assert_no_match(/depends_on:/, content)
+    end
+  end
+
+  def test_skip_devcontainer
+    run_generator [ destination_root, "--skip_devcontainer" ]
+
+    assert_no_file(".devcontainer/devcontainer.json")
+    assert_no_file(".devcontainer/Dockerfile")
+    assert_no_file(".devcontainer/docker-compose.yml")
+  end
+
   private
     def assert_node_files
       assert_file ".node-version" do |content|