Ruby on Rails with Sidekiq and docker compose

.env

PORT=3000

REDIS_PORT=6379
SIDEKIQ_REDIS_URL=redis://redis:6379/0

APP_DATABASE_HOST=database
APP_DATABASE_PORT=5432
APP_DATABASE_NAME=app_development
APP_DATABASE_USERNAME=postgres
APP_DATABASE_PASSWORD=postgres

database.yml

# config/database.yml

default: &default
  adapter: postgresql
  encoding: unicode
  pool: <%= ENV.fetch("RAILS_MAX_THREADS") { 5 } %>
  host: <%= ENV['APP_DATABASE_HOST'] %>
  database: <%= ENV['APP_DATABASE_NAME'] %>
  username: <%= ENV['APP_DATABASE_USERNAME'] %>
  password: <%= ENV['APP_DATABASE_PASSWORD'] %>

development:
  <<: *default

test:
  <<: *default
  database: app_test

production:
  <<: *default

docker-compose.yml

version: "3.3"
services: 
  app: 
    build: .
    env_file:
      - .env
    volumes: 
      - ".:/app"
    ports: 
      - ${PORT}:${PORT}
    depends_on:
      - database

  database:
    image: postgres:13.2
    restart: always
    environment:
      POSTGRES_PASSWORD: postgres
    ports:
      - ${APP_DATABASE_PORT}:${APP_DATABASE_PORT}
    volumes:
      - "pg_volume:/var/lib/postgresql/data"

  redis:
    image: redis
    ports:
      - ${REDIS_PORT}:${REDIS_PORT}

  sidekiq:
    build: .
    depends_on:
      - database
      - redis
    volumes:
      - .:/app
    env_file:
      - .env
    command: bundle exec sidekiq

volumes:
  pg_volume:
    driver: local

Dockerfile

FROM ruby:2.7.2

RUN curl -sS https://dl.yarnpkg.com/debian/pubkey.gpg | apt-key add -
RUN echo "deb https://dl.yarnpkg.com/debian/ stable main" | tee /etc/apt/sources.list.d/yarn.list
RUN apt-get update -qq && apt-get install -y build-essential nodejs yarn

RUN mkdir /app

WORKDIR /app

ADD Gemfile /app/Gemfile
ADD Gemfile.lock /app/Gemfile.lock

RUN bundle install

ADD . /app

CMD rm -f tmp/pids/server.pid && bin/rails server -b '0.0.0.0'

Gemfile

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

ruby '2.7.2'

gem 'rails', '~> 6.1.4', '>= 6.1.4.1'

routes.rb

# config/routes.rb
require 'sidekiq/web'

Rails.application.routes.draw do
  mount Sidekiq::Web, at: '/sidekiq'
end

sidekiq.rb

# config/initializers/sidekiq.rb
Sidekiq.configure_server do |config|
  config.redis = { url: ENV['SIDEKIQ_REDIS_URL'] }
end

Sidekiq.configure_client do |config|
  config.redis = { url: ENV['SIDEKIQ_REDIS_URL'] }
end

Create initial files:

touch docker-compose.yml Dockerfile Gemfile Gemfile.lock .env

Copy contents of the corresponding files above.

Create new rails app:

docker-compose run --no-deps app rails new . --force --database=postgresql

Add gem 'sidekiq' to Gemfile

touch config/initializers/sidekiq.rb config/routes.rb config/database.yml

Copy contents of the corresponding files above.

Build docker images and install webpacker:

docker-compose build
docker-compose run app bundle exec rails webpacker:install

Create the database:

docker-compose up -d database
docker-compose run app rake db:create

Run the app:

docker-compose up -d

The app is running on localhost:3000. The Sidekiq web interface can be accessed at http://localhost:3000/sidekiq