Docker ComposeでのRailsアプリのDocker化方法

みなさま、ごきげんよう！今回はDocker ComposeでのRailsアプリのDocker化方法についてごく簡単にまとめてみました。前提として、Docker、Docker ComposeやRuby on Railsの基礎的な知識をお持ちの方が対象です。

 条件

• Docker未使用の環境で動作するRailsのwebアプリを用意。
• RailsアプリはRubyのバージョン3.3.0、dbとしてpostgresのバージョン12を使用。
• docker-compose upでRailsプロセスとdbが起動し、http://localhost:3000 でこのWebアプリでアクセスできるようにする。
• ホストのファイルシステムとコンテナのファイルシステムを同期。

 Docker化の手順

 1.必要なファイル類の準備

• Railsアプリのためアプリケーション用とdb用のコンテナを使用。複数コンテナを使うため、Dockerfileとdocker-compose.ymlを用意。
• WebアプリのソースがGitHub等リモートのリポジトリで公開されている場合クローンしてくる。
• 土台となるDockerfileとdocker-compose.ymlを作成。
• railsのdatabase.yml等に記述が不足している場合は必要な内容を追記。　　　　　　　　　　
  
  
  
  
  
  FROM ruby:3.3.0

  RUN apt-get update && apt-get install -y \

  build-essential \

  libpq-dev \

  nodejs \

  postgresql-client \

  yarn

  WORKDIR /rails-docker

  COPY Gemfile Gemfile.lock /rails-docker/

  RUN bundle install

  Dockerfile Dockerfile

 

version: '3'

volumes:

db-data:

services:

db:

image: postgres:12

volumes:

- 'db-data:/var/lib/postgresql/data'

environment:

- 'POSTGRES_USER=postgres'

- 'POSTGRES_PASSWORD=postgres'

web:

build: .

command: >

bash -c "rm -f tmp/pids/server.pid && rails db:create
&& rails db:migrate && rails s -b 0.0.0.0"

ports:

- '3000:3000'

volumes:

- '.:/rails-docker'

environment:

- 'DATABASE_PASSWORD=postgres'

tty: true

stdin_open: true

depends_on:

- db

links:

- db

 

source "https://rubygems.org"

git_source(:github) { |repo| "https://github.com/#{repo}.git" }

ruby "3.3.0"

gem 'concurrent-ruby', '1.1.9'

# Bundle edge Rails instead: gem "rails", github: "rails/rails", branch: "main"

gem "rails", "~> 7.0.6"

gem 'bundler', '~> 2.5', '>= 2.5.3'

gem 'rubygems-update', '~> 3.5', '>= 3.5.3'

# The original asset pipeline for Rails https://github.com/rails/sprockets-rails

gem "sprockets-rails"

# Use postgresql as the database for Active Record

gem 'pg', '~> 1.1'

# Use the Puma web server https://github.com/puma/puma

gem "puma", "~> 5.0"

# Use JavaScript with ESM import maps https://github.com/rails/importmap-rails

gem "importmap-rails"

# Hotwire's SPA-like page accelerator https://turbo.hotwired.dev

gem "turbo-rails"

# Hotwire's modest JavaScript framework https://stimulus.hotwired.dev

gem "stimulus-rails"

# Build JSON APIs with ease https://github.com/rails/jbuilder

gem "jbuilder"

# Use Redis adapter to run Action Cable in production

# gem "redis", "~> 4.0"

# Use Kredis to get higher-level data types in Redis https://github.com/rails/kredis

# gem "kredis"

# Use Active Model has_secure_password [https://guides.rubyonrails.org

/active_model_basics.html#securepassword]

# gem "bcrypt", "~> 3.1.7"

# Windows does not include zoneinfo files, so bundle the tzinfo-data gem

gem "tzinfo-data", platforms: %i[ mingw mswin x64_mingw jruby ]

# Reduces boot times through caching; required in config/boot.rb

gem "bootsnap", require: false

# Use Sass to process CSS

# gem "sassc-rails"

# Use Active Storage variants [https://guides.rubyonrails.org/active_storage_overview.

html#transforming-images]

# gem "image_processing", "~> 1.2"

group :development, :test do

# See https://guides.rubyonrails.org/debugging_rails_applications.

html#debugging-with-the-debug-gem

gem "debug", platforms: %i[ mri mingw x64_mingw ]

end

group :development do

# Use console on exceptions pages https://github.com/rails/web-console

gem "web-console"

# Add speed badges https://github.com/MiniProfiler/rack-mini-profiler

# gem "rack-mini-profiler"

# Speed up commands on slow machines / big apps https://github.com/rails/spring

# gem "spring"

end

group :test do

# Use system testing https://guides.rubyonrails.org/testing.html#system-testing

gem "capybara"

gem "selenium-webdriver"

gem "webdrivers"

end

 

 

GEM

remote: https://rubygems.org/

specs:

actioncable (7.0.8)

actionpack (= 7.0.8)

activesupport (= 7.0.8)

nio4r (~> 2.0)

websocket-driver (>= 0.6.1)

actionmailbox (7.0.8)

actionpack (= 7.0.8)

activejob (= 7.0.8)

activerecord (= 7.0.8)

activestorage (= 7.0.8)

activesupport (= 7.0.8)

mail (>= 2.7.1)

net-imap

net-pop

net-smtp

actionmailer (7.0.8)

actionpack (= 7.0.8)

actionview (= 7.0.8)

activejob (= 7.0.8)

activesupport (= 7.0.8)

mail (~> 2.5, >= 2.5.4)

net-imap

net-pop

net-smtp

rails-dom-testing (~> 2.0)

actionpack (7.0.8)

actionview (= 7.0.8)

activesupport (= 7.0.8)

rack (~> 2.0, >= 2.2.4)

rack-test (>= 0.6.3)

rails-dom-testing (~> 2.0)

rails-html-sanitizer (~> 1.0, >= 1.2.0)

actiontext (7.0.8)

actionpack (= 7.0.8)

activerecord (= 7.0.8)

activestorage (= 7.0.8)

activesupport (= 7.0.8)

globalid (>= 0.6.0)

nokogiri (>= 1.8.5)

actionview (7.0.8)

activesupport (= 7.0.8)

builder (~> 3.1)

erubi (~> 1.4)

rails-dom-testing (~> 2.0)

rails-html-sanitizer (~> 1.1, >= 1.2.0)

activejob (7.0.8)

activesupport (= 7.0.8)

globalid (>= 0.3.6)

activemodel (7.0.8)

activesupport (= 7.0.8)

activerecord (7.0.8)

activemodel (= 7.0.8)

activesupport (= 7.0.8)

activestorage (7.0.8)

actionpack (= 7.0.8)

activejob (= 7.0.8)

activerecord (= 7.0.8)

activesupport (= 7.0.8)

marcel (~> 1.0)

mini_mime (>= 1.1.0)

activesupport (7.0.8)

concurrent-ruby (~> 1.0, >= 1.0.2)

i18n (>= 1.6, < 2)

minitest (>= 5.1)

tzinfo (~> 2.0)

addressable (2.8.6)

public_suffix (>= 2.0.2, < 6.0)

bindex (0.8.1)

bootsnap (1.17.1)

msgpack (~> 1.2)

builder (3.2.4)

capybara (3.39.2)

addressable

matrix

mini_mime (>= 0.1.3)

nokogiri (~> 1.8)

rack (>= 1.6.0)

rack-test (>= 0.6.3)

regexp_parser (>= 1.5, < 3.0)

xpath (~> 3.2)

concurrent-ruby (1.2.3)

crass (1.0.6)

date (3.3.4)

debug (1.9.1)

irb (~> 1.10)

reline (>= 0.3.8)

erubi (1.12.0)

globalid (1.2.1)

activesupport (>= 6.1)

i18n (1.14.1)

concurrent-ruby (~> 1.0)

importmap-rails (2.0.1)

actionpack (>= 6.0.0)

activesupport (>= 6.0.0)

railties (>= 6.0.0)

io-console (0.7.1)

irb (1.11.1)

rdoc

reline (>= 0.4.2)

jbuilder (2.11.5)

actionview (>= 5.0.0)

activesupport (>= 5.0.0)

loofah (2.22.0)

crass (~> 1.0.2)

nokogiri (>= 1.12.0)

mail (2.8.1)

mini_mime (>= 0.1.1)

net-imap

net-pop

net-smtp

marcel (1.0.2)

matrix (0.4.2)

method_source (1.0.0)

mini_mime (1.1.5)

minitest (5.21.1)

msgpack (1.7.2)

net-imap (0.4.9.1)

date

net-protocol

net-pop (0.1.2)

net-protocol

net-protocol (0.2.2)

timeout

net-smtp (0.4.0.1)

net-protocol

nio4r (2.7.0)

nokogiri (1.16.0-aarch64-linux)

racc (~> 1.4)

nokogiri (1.16.0-arm-linux)

racc (~> 1.4)

nokogiri (1.16.0-arm64-darwin)

racc (~> 1.4)

nokogiri (1.16.0-x86-linux)

racc (~> 1.4)

nokogiri (1.16.0-x86_64-darwin)

racc (~> 1.4)

nokogiri (1.16.0-x86_64-linux)

racc (~> 1.4)

pg (1.5.4)

psych (5.1.2)

stringio

public_suffix (5.0.4)

puma (5.6.8)

nio4r (~> 2.0)

racc (1.7.3)

rack (2.2.8)

rack-test (2.1.0)

rack (>= 1.3)

rails (7.0.8)

actioncable (= 7.0.8)

actionmailbox (= 7.0.8)

actionmailer (= 7.0.8)

actionpack (= 7.0.8)

actiontext (= 7.0.8)

actionview (= 7.0.8)

activejob (= 7.0.8)

activemodel (= 7.0.8)

activerecord (= 7.0.8)

activestorage (= 7.0.8)

activesupport (= 7.0.8)

bundler (>= 1.15.0)

railties (= 7.0.8)

rails-dom-testing (2.2.0)

activesupport (>= 5.0.0)

minitest

nokogiri (>= 1.6)

rails-html-sanitizer (1.6.0)

loofah (~> 2.21)

nokogiri (~> 1.14)

railties (7.0.8)

actionpack (= 7.0.8)

activesupport (= 7.0.8)

method_source

rake (>= 12.2)

thor (~> 1.0)

zeitwerk (~> 2.5)

rake (13.1.0)

rdoc (6.6.2)

psych (>= 4.0.0)

regexp_parser (2.9.0)

reline (0.4.2)

io-console (~> 0.5)

rexml (3.2.6)

rubyzip (2.3.2)

selenium-webdriver (4.10.0)

rexml (~> 3.2, >= 3.2.5)

rubyzip (>= 1.2.2, < 3.0)

websocket (~> 1.0)

sprockets (4.2.1)

concurrent-ruby (~> 1.0)

rack (>= 2.2.4, < 4)

sprockets-rails (3.4.2)

actionpack (>= 5.2)

activesupport (>= 5.2)

sprockets (>= 3.0.0)

stimulus-rails (1.3.3)

railties (>= 6.0.0)

stringio (3.1.0)

thor (1.3.0)

timeout (0.4.1)

turbo-rails (1.5.0)

actionpack (>= 6.0.0)

activejob (>= 6.0.0)

railties (>= 6.0.0)

tzinfo (2.0.6)

concurrent-ruby (~> 1.0)

web-console (4.2.1)

actionview (>= 6.0.0)

activemodel (>= 6.0.0)

bindex (>= 0.4.0)

railties (>= 6.0.0)

webdrivers (5.3.1)

nokogiri (~> 1.6)

rubyzip (>= 1.3.0)

selenium-webdriver (~> 4.0, < 4.11)

websocket (1.2.10)

websocket-driver (0.7.6)

websocket-extensions (>= 0.1.0)

websocket-extensions (0.1.5)

xpath (3.2.0)

nokogiri (~> 1.8)

zeitwerk (2.6.12)

PLATFORMS

aarch64-linux

arm-linux

arm64-darwin

x86-linux

x86_64-darwin

x86_64-linux

DEPENDENCIES

bootsnap

capybara

concurrent-ruby (= 1.2.3)

debug

importmap-rails

jbuilder

pg (~> 1.5, >= 1.5.4)

puma (~> 5.0)

rails (~> 7.0.6)

selenium-webdriver

sprockets-rails

stimulus-rails

turbo-rails

tzinfo-data

web-console

webdrivers

RUBY VERSION

ruby 3.3.0

BUNDLED WITH

2.5.3

 

 

# PostgreSQL. Versions 9.3 and up are supported.

#

# Install the pg driver:

# gem install pg

# On macOS with Homebrew:

# gem install pg -- --with-pg-config=/usr/local/bin/pg_config

# On macOS with MacPorts:

# gem install pg -- --with-pg-config=/opt/local/lib/postgresql84/bin/pg_config

# On Windows:

# gem install pg

# Choose the win32 build.

# Install PostgreSQL and put its /bin directory on your path.

#

# Configure Using Gemfile

# gem "pg"

#

default: &default

adapter: postgresql

encoding: unicode

host: db

username: postgres

password: postgres

pool: <%= ENV.fetch("RAILS_MAX_THREADS") { 5 } %>

timeout: 5000

development:

<<: *default

database: rails-docker_development

test:

<<: *default

database: rails-docker_test

production:

<<: *default

database: rails-docker_production

 

 2.docker-compose upで動作確認

最後にdocker-compose upを入力してRailsプロセスとdb起動まで完了するか確認。エラーなくコンテナが起動し、http://localhost:3000 でWebアプリへアクセスできたらDocker化完了。



最後に

Rails bundlerは相互に複雑な依存関係にあるため各々のバージョンを揃えることに個人的には苦心しました。
Docker Composeのみならず、Ruby on Railsの知見も高まりますので良かったら皆様もお試しください！
ではまた👋

 参考

• • 米国AI開発者がゼロから教えるDocker講座 | Udemy
  • クィックスタート: Compose と Rails | Docker ドキュメント