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 `--no-devcontainer` option.

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

actionpack/lib/action_dispatch/system_test_case.rb

@@ -159,7 +159,7 @@ def self.driven_by(driver, using: :chrome, screen_size: [1400, 1400], options: {
       self.driver = SystemTesting::Driver.new(driver, **driver_options, &capabilities)
     end
 
-    # Configuration for the System Test application server
+    # Configuration for the System Test application server.
     #
     # By default this is localhost. This method allows the host and port to be specified manually.
     def self.served_by(host:, port:)

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 Kredis, ActionCable etc.
+     - 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 `--no-devcontainer` option.
+
+    *Andrew Novoselac & Rafael Mendonça França*
+
 *   Introduce `SystemTestCase#served_by` for configuring the System Test application server
 
     By default this is localhost. This method allows the host and port to be specified manually.

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 :devcontainer,        type: :boolean, default: true,
+                                           desc: "Generate 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[: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/database.rb

@@ -90,6 +90,14 @@ def mysql_socket
             "/opt/lampp/var/mysql/mysql.sock"         # xampp for linux
           ].find { |f| File.exist?(f) } unless Gem.win_platform?
         end
+
+        def mysql_database_host
+          if options[:devcontainer]
+            "<%= ENV.fetch(\"DB_HOST\") { \"localhost\" } %>"
+          else
+            "localhost"
+          end
+        end
     end
   end
 end

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

@@ -266,6 +266,14 @@ 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
@@ -455,6 +463,11 @@ def create_storage_files
         build(:storage)
       end
 
+      def create_devcontainer_files
+        return if skip_devcontainer? || options[:dummy_app]
+        build(:devcontainer)
+      end
+
       def delete_app_assets_if_api_option
         if options[:api]
           remove_dir "app/assets"
@@ -592,6 +605,35 @@ 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
+
+      def devcontainer_variables
+        return @devcontainer_variables if @devcontainer_variables
+
+        @devcontainer_variables = {}
+
+        @devcontainer_variables["CAPYBARA_SERVER_PORT"] = "45678" if depends_on_system_test?
+        @devcontainer_variables["SELENIUM_HOST"] = "selenium" if depends_on_system_test?
+        @devcontainer_variables["REDIS_URL"] = "redis://redis:6379/1" unless options.skip_active_job? && options.skip_action_cable?
+        @devcontainer_variables["DB_HOST"] = "postgres" if options.database == "postgresql"
+        @devcontainer_variables["DB_HOST"] = "mysql" if options.database == "mysql"
+        @devcontainer_variables["DB_HOST"] = "mariadb" if options.database == "trilogy"
+
+        @devcontainer_variables
+      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 +1,34 @@
+// 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 %>",
+  "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": {}
+  },
+
+<%- if !devcontainer_variables.empty? -%>
+  "containerEnv": {
+    <%= devcontainer_variables.map { |key, value| "\"#{key}\": \"#{value}\"" }.join(",\n    ") %>
+  },
+<%- 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": [],
+
+  // Configure tool-specific properties.
+  // "customizations": {},
+
+  // Uncomment to connect as root instead. More info: https://aka.ms/dev-containers-non-root.
+  // "remoteUser": "root",
+
+  // Use 'postCreateCommand' to run commands after the container is created.
+  "postCreateCommand": "bin/setup"
+}

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/lib/rails/generators/rails/app/templates/config/databases/mysql.yml.tt

@@ -18,7 +18,7 @@ default: &default
 <% if mysql_socket -%>
   socket: <%= mysql_socket %>
 <% else -%>
-  host: localhost
+  host: <%= mysql_database_host %>
 <% end -%>
 
 development:

railties/lib/rails/generators/rails/app/templates/config/databases/postgresql.yml.tt

@@ -18,6 +18,13 @@ default: &default
   # For details on connection pooling, see Rails configuration guide
   # https://guides.rubyonrails.org/configuring.html#database-pooling
   pool: <%%= ENV.fetch("RAILS_MAX_THREADS") { 5 } %>
+<% if options[:devcontainer] -%>
+  <%% if ENV["DB_HOST"] %>
+  host: <%%= ENV["DB_HOST"] %>
+  username: postgres
+  password: postgres
+  <%% end %>
+<% end %>
 
 development:
   <<: *default

railties/lib/rails/generators/rails/app/templates/config/databases/trilogy.yml.tt

@@ -18,7 +18,7 @@ default: &default
 <% if mysql_socket -%>
   socket: <%= mysql_socket %>
 <% else -%>
-  host: localhost
+  host: <%= mysql_database_host %>
 <% end -%>
 
 development:

railties/lib/rails/generators/rails/app/templates/test/application_system_test_case.rb.tt

@@ -1,5 +1,18 @@
 require "test_helper"
 
 class ApplicationSystemTestCase < ActionDispatch::SystemTestCase
+<% if skip_devcontainer? -%>
   driven_by :selenium, using: :headless_chrome, screen_size: [ 1400, 1400 ]
+<% else -%>
+  if ENV["CAPYBARA_SERVER_PORT"]
+    served_by host: "rails-app", port: ENV["CAPYBARA_SERVER_PORT"]
+
+    driven_by :selenium, using: :headless_chrome, screen_size: [ 1400, 1400 ], options: {
+      browser: :remote,
+      url: "http://#{ENV["SELENIUM_HOST"]}:4444",
+    }
+  else
+    driven_by :selenium, using: :headless_chrome, screen_size: [ 1400, 1400 ]
+  end
+<% end -%>
 end