既存のRailsアプリからAction CableやAction Mailerなどの不要な機能を取り除く

$ rails new -h | grep Skip
      [--skip-namespace], [--no-skip-namespace]              # Skip namespace (affects only isolated engines)
      [--skip-collision-check], [--no-skip-collision-check]  # Skip collision check
  -G, [--skip-git], [--no-skip-git]                          # Skip .gitignore file
      [--skip-keeps], [--no-skip-keeps]                      # Skip source control .keep files
  -M, [--skip-action-mailer], [--no-skip-action-mailer]      # Skip Action Mailer files
      [--skip-action-mailbox], [--no-skip-action-mailbox]    # Skip Action Mailbox gem
      [--skip-action-text], [--no-skip-action-text]          # Skip Action Text gem
  -O, [--skip-active-record], [--no-skip-active-record]      # Skip Active Record files
      [--skip-active-job], [--no-skip-active-job]            # Skip Active Job
      [--skip-active-storage], [--no-skip-active-storage]    # Skip Active Storage files
  -P, [--skip-puma], [--no-skip-puma]                        # Skip Puma related files
  -C, [--skip-action-cable], [--no-skip-action-cable]        # Skip Action Cable files
  -S, [--skip-sprockets], [--no-skip-sprockets]              # Skip Sprockets files
  -J, [--skip-javascript], [--no-skip-javascript]            # Skip JavaScript files
      [--skip-turbolinks], [--no-skip-turbolinks]            # Skip turbolinks gem
      [--skip-jbuilder], [--no-skip-jbuilder]                # Skip jbuilder gem
  -T, [--skip-test], [--no-skip-test]                        # Skip test files
      [--skip-system-test], [--no-skip-system-test]          # Skip system test files
      [--skip-bootsnap], [--no-skip-bootsnap]                # Skip bootsnap gem
      [--no-rc], [--no-no-rc]                                # Skip loading of extra configuration options from .railsrc file
  -s, [--skip], [--no-skip]        # Skip files that already exist

$ rails new sample_app -G -B
$ mv sample_app rails-all

$ rails new sample_app -G -B -C
$ mv sample_app rails-without-action-cable

$ diff -r -x credentials.yml.enc -x master.key rails-all rails-without-action-cable

$ diff -r -x credentials.yml.enc -x master.key rails-all rails-without-action-cable
diff -r -x credentials.yml.enc -x master.key rails-all/Gemfile rails-without-action-cable/Gemfile
20,21d19
< # Use Redis adapter to run Action Cable in production
< # gem 'redis', '~> 4.0'
Only in rails-all/app: channels
Only in rails-all/app/javascript: channels
diff -r -x credentials.yml.enc -x master.key rails-all/app/javascript/packs/application.js rails-without-action-cable/app/javascript/packs/application.js
9d8
< import "channels"
diff -r -x credentials.yml.enc -x master.key rails-all/config/application.rb rails-without-action-cable/config/application.rb
3c3,16
< require "rails/all"
---
> require "rails"
> # Pick the frameworks you want:
> require "active_model/railtie"
> require "active_job/railtie"
> require "active_record/railtie"
> require "active_storage/engine"
> require "action_controller/railtie"
> require "action_mailer/railtie"
> require "action_mailbox/engine"
> require "action_text/engine"
> require "action_view/railtie"
> # require "action_cable/engine"
> require "sprockets/railtie"
> require "rails/test_unit/railtie"
Only in rails-all/config: cable.yml
diff -r -x credentials.yml.enc -x master.key rails-all/config/environments/production.rb rails-without-action-cable/config/environments/production.rb
43,47d42
<   # Mount Action Cable outside main process or domain.
<   # config.action_cable.mount_path = nil
<   # config.action_cable.url = 'wss://example.com/cable'
<   # config.action_cable.allowed_request_origins = [ 'http://example.com', /http:\/\/example.*/ ]
<
diff -r -x credentials.yml.enc -x master.key rails-all/package.json rails-without-action-cable/package.json
7,8c7
<     "@rails/activestorage": "^6.0.0",
<     "@rails/actioncable": "^6.0.0"
---
>     "@rails/activestorage": "^6.0.0"
Only in rails-all/test: channels

 gem 'turbolinks', '~> 5'
 # Build JSON APIs with ease. Read more: https://github.com/rails/jbuilder
 gem 'jbuilder', '~> 2.10'
-# Use Redis adapter to run Action Cable in production
-# gem 'redis', '~> 4.0'
 # Use Active Model has_secure_password
 # gem 'bcrypt', '~> 3.1.7'

 require_relative 'boot'

-require 'rails/all'
+require 'rails'
+require 'active_model/railtie'
+require 'active_job/railtie'
+require 'active_record/railtie'
+require 'active_storage/engine'
+require 'action_controller/railtie'
+require 'action_mailer/railtie'
+require 'action_mailbox/engine'
+require 'action_text/engine'
+require 'action_view/railtie'
+require 'sprockets/railtie'
+require 'rails/test_unit/railtie'

 # Require the gems listed in Gemfile, including any gems
 # you've limited to :test, :development, or :production.

   "name": "masamune",
   "private": true,
   "dependencies": {
-    "@rails/actioncable": "^6.0.4",
     "@rails/activestorage": "^6.0.4",
     "@rails/ujs": "^6.0.4",
     "@rails/webpacker": "5.1.1",

 require("@rails/ujs").start()
 require("turbolinks").start()
 require("@rails/activestorage").start()
-require("channels")

 require("chartkick/chart.js")
 require("admin-lte")

   # Store uploaded files on the local file system (see config/storage.yml for options).
   config.active_storage.service = :local

-  # Mount Action Cable outside main process or domain.
-  # config.action_cable.mount_path = nil
-  # config.action_cable.url = 'wss://example.com/cable'
-  # config.action_cable.allowed_request_origins = [ 'http://example.com', /http:\/\/example.*/ ]
-
   # Force all access to the app over SSL, use Strict-Transport-Security, and use secure cookies.
   # config.force_ssl = true