Add default Dockerfiles (rails#46762)

Author: dhh

railties/CHANGELOG.md

@@ -1,3 +1,31 @@
+*   Add Docker files by default to new apps: Dockerfile, .dockerignore, bin/docker-entrypoint.
+    These files can be skipped with `--skip-docker`. They're intended as a starting point for
+    a production deploy of the application. Not intended for development (see Docked Rails for that).
+
+    Example:
+
+    ```
+    docker build -t app .
+    docker volume create app-storage
+    docker run --rm -it -v app-storage:/rails/storage -p 3000:3000 --env RAILS_MASTER_KEY=<see config/master.key> app
+    ```
+
+    You can also start a console or a runner from this image:
+
+    ```
+    docker run --rm -it -v app-storage:/rails/storage --env RAILS_MASTER_KEY=<see config/master.key> app console
+    ```
+
+    To create a multi-platform image on Apple Silicon to deploy on AMD or Intel and push to Docker Hub for user/app:
+
+    ```
+    docker login -u <user>
+    docker buildx create --use
+    docker buildx build --push --platform=linux/amd64,linux/arm64 -t <user/image> .
+    ```
+
+    *DHH*
+
 *   Add ENV["SECRET_KEY_BASE_DUMMY"] for starting production environment with a generated secret base key,
     which can be used to run tasks like `assets:precompile` without making the RAILS_MASTER_KEY available
     to the build process.

railties/lib/rails/generators/app_base.rb

@@ -37,6 +37,9 @@ def self.add_shared_options_for(name)
         class_option :skip_git,            type: :boolean, aliases: "-G", default: nil,
                                            desc: "Skip git init, .gitignore and .gitattributes"
 
+        class_option :skip_docker,         type: :boolean, default: nil,
+                                           desc: "Skip Dockerfile, .dockerignore and bin/docker-entrypoint"
+
         class_option :skip_keeps,          type: :boolean, default: nil,
                                            desc: "Skip source control .keep files"
 

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

@@ -70,6 +70,14 @@ def gitattributes
       template "gitattributes", ".gitattributes"
     end
 
+    def dockerfiles
+      template "Dockerfile"
+      template "dockerignore", ".dockerignore"
+
+      template "docker-entrypoint", "bin/docker-entrypoint"
+      chmod "bin/docker-entrypoint", 0755 & ~File.umask, verbose: false
+    end
+
     def version_control
       if !options[:skip_git] && !options[:pretend]
         run git_init_command, capture: options[:quiet], abort_on_failure: false
@@ -342,6 +350,12 @@ def update_active_storage
       end
       remove_task :update_active_storage
 
+      def create_dockerfiles
+        unless options[:skip_docker]
+          build(:dockerfiles)
+        end
+      end
+
       def create_config_files
         build(:config)
       end

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

@@ -0,0 +1,50 @@
+# Make sure it matches the Ruby version in .ruby-version and Gemfile
+ARG RUBY_VERSION=<%= Gem.ruby_version %>
+FROM ruby:$RUBY_VERSION
+
+<% if using_node? -%>
+# Install JavaScript dependencies and libvips for Active Storage
+ARG NODE_MAJOR_VERSION=19
+RUN curl -sL https://deb.nodesource.com/setup_$NODE_MAJOR_VERSION.x | bash -
+RUN apt-get update -qq && \
+    apt-get install -y build-essential libvips nodejs && \
+    apt-get clean && \
+    rm -rf /var/lib/apt/lists/* /usr/share/doc /usr/share/man && \
+    npm install -g yarn
+
+<% elsif !skip_active_storage? -%>
+# Install libvips for Active Storage preview support
+RUN apt-get update -qq && \
+    apt-get install -y build-essential libvips && \
+    apt-get clean && \
+    rm -rf /var/lib/apt/lists/* /usr/share/doc /usr/share/man
+
+<% end -%>
+# Rails app lives here
+WORKDIR /rails
+
+# Set production environment
+ENV RAILS_LOG_TO_STDOUT="1" \
+    RAILS_SERVE_STATIC_FILES="true" \
+    RAILS_ENV="production" \
+    BUNDLE_WITHOUT="development:test"
+
+# Install application gems
+COPY Gemfile Gemfile.lock ./
+RUN bundle install
+
+# Copy application code
+COPY . .
+
+<% if depend_on_bootsnap? -%>
+# Precompile bootsnap code for faster boot times
+RUN bundle exec bootsnap precompile --gemfile app/ lib/
+
+<% end -%>
+# Precompiling assets for production without requiring secret RAILS_MASTER_KEY
+RUN SECRET_KEY_BASE_DUMMY=1 bundle exec rails assets:precompile
+
+# Entrypoint prepares database and starts app on 0.0.0.0:3000 by default,
+# but can also take a rails command, like "console" or "runner" to start instead.
+ENTRYPOINT ["/rails/bin/docker-entrypoint"]
+EXPOSE 3000

railties/lib/rails/generators/rails/app/templates/docker-entrypoint.tt

@@ -0,0 +1,12 @@
+#!/bin/sh
+
+if [ $# -eq 0 ]; then
+  # Create new or migrate existing database
+  ./bin/rails db:prepare
+
+  # Start the server by default
+  exec bin/rails server
+else
+  # Allow other commands, like console or runner, to be called
+  exec bin/rails "$@"
+fi

railties/lib/rails/generators/rails/app/templates/dockerignore.tt

@@ -0,0 +1,34 @@
+# See https://docs.docker.com/engine/reference/builder/#dockerignore-file for more about ignoring files.
+
+# Ignore bundler config.
+/.bundle
+
+# Ignore all default key files
+config/master.key
+config/credentials/*.key
+
+# Ignore all logfiles and tempfiles.
+/log/*
+/tmp/*
+<% if keeps? -%>
+!/log/.keep
+!/tmp/.keep
+
+# Ignore pidfiles, but keep the directory.
+/tmp/pids/*
+!/tmp/pids/
+!/tmp/pids/.keep
+<% end -%>
+
+# Ignore storage (uploaded files in development and any SQLite databases).
+/storage/*
+<% if keeps? -%>
+!/storage/.keep
+/tmp/storage/*
+!/tmp/storage/
+!/tmp/storage/.keep
+<% end -%>
+<% unless options.api? -%>
+
+/public/assets
+<% end -%>

railties/test/generators/api_app_generator_test.rb

@@ -110,9 +110,11 @@ def test_app_update_does_not_generate_unnecessary_bin_files
     def default_files
       %w(.gitignore
         .ruby-version
+        .dockerignore
         README.md
         Gemfile
         Rakefile
+        Dockerfile
         config.ru
         app/channels
         app/controllers
@@ -121,6 +123,7 @@ def default_files
         app/views/layouts
         app/views/layouts/mailer.html.erb
         app/views/layouts/mailer.text.erb
+        bin/docker-entrypoint
         bin/rails
         bin/rake
         bin/setup

railties/test/generators/app_generator_test.rb

@@ -7,10 +7,12 @@
 DEFAULT_APP_FILES = %w(
   .gitattributes
   .gitignore
+  .dockerignore
   .ruby-version
   README.md
   Gemfile
   Rakefile
+  Dockerfile
   config.ru
   app/assets/config/manifest.js
   app/assets/images
@@ -34,6 +36,7 @@
   app/views/layouts/application.html.erb
   app/views/layouts/mailer.html.erb
   app/views/layouts/mailer.text.erb
+  bin/docker-entrypoint
   bin/rails
   bin/rake
   bin/setup
@@ -1006,6 +1009,14 @@ def test_gitignore
     end
   end
 
+  def test_dockerignore
+    run_generator
+
+    assert_file ".dockerignore" do |content|
+      assert_match(/config\/master\.key/, content)
+    end
+  end
+
   def test_system_tests_directory_generated
     run_generator
 

railties/test/generators/shared_generator_tests.rb

@@ -132,6 +132,13 @@ def test_skip_keeps
     assert_no_file("app/models/concerns/.keep")
   end
 
+  def test_skip_docker
+    run_generator [destination_root, "--skip-docker", "--full"]
+    assert_no_file(".dockerignore")
+    assert_no_file("Dockerfile")
+    assert_no_file("bin/docker-entrypoint")
+  end
+
   def test_default_frameworks_are_required_when_others_are_removed
     run_generator [
       destination_root,