Rails + MySQL environment construction with Docker

Overview

Remake https://docs.docker.com/compose/rails/ for MySQL.

procedure:

1. Preparation of configuration file
2. Create Dockerfile
3. Create Gemfile
4. Create entrypoint.sh
5. Create docker-compose.yaml
6. Build
7. Initialize rails project
8. Image update
9. Connect with DB
10. Display confirmation

Preparation of configuration file

Dockerfile creation

FROM ruby:2.5
RUN apt-get update -qq && apt-get install -y nodejs build-essential libpq-dev
WORKDIR /app
COPY Gemfile /app/Gemfile
COPY Gemfile.lock /app/Gemfile.lock
RUN bundle install
COPY . /app

# Add a script to be executed every time the container starts.
COPY entrypoint.sh /usr/bin/
RUN chmod +x /usr/bin/entrypoint.sh
ENTRYPOINT ["entrypoint.sh"]
EXPOSE 3000

# Start the main process.
CMD ["rails", "server", "-b", "0.0.0.0"]

Create Gemfile

Create a Gemfile in the project root

source 'https://rubygems.org'
gem 'rails', '~>5'

Create Gemfile.lock

touch Gemfile.lock

Create entrypoint.sh

#!/bin/bash
set -e

# Remove a potentially pre-existing server.pid for Rails.
rm -f /myapp/tmp/pids/server.pid

# Then exec the container's main process (what's set as CMD in the Dockerfile).
exec "$@"

Create docker-compose.yaml

Create volume as db_data to make DB data persistent

version: "3"
services:
  db:
    image: mysql:8.0
    volumes:
      - db_data:/var/lib/mysql
    command: --default-authentication-plugin=mysql_native_password
    ports: 
      - "3306:3306"
    environment:
      MYSQL_ROOT_PASSWORD: root
      MYSQL_DATABASE: root
      MYSQL_USER: admin
      MYSQL_PASSWORD: password
  web:
    build: .
    command: bash -c "rm -f tmp/pids/server.pid && bundle exec rails s -p 3000 -b '0.0.0.0'"
    volumes:
      - .:/app
    ports:
      - "3000:3000"
    depends_on:
      - db
volumes:
  db_data:

Build

Create a Rail project.

Rails project initialization

Run rails new on the web to initialize rails. Gemfile is updated automatically.

docker-compose run --no-deps web rails new . --force --database=mysql

image update

The Gemfile has been updated, so build the image again.

docker-compose build

Connect with DB

Write DB settings to config/database.yml

default: &default
  adapter: mysql2
  encoding: utf8
  pool: <%= ENV.fetch("RAILS_MAX_THREADS") { 5 } %>
  username: root
  password: root
  host: db

development:
  <<: *default
  database: app_development

test:
  <<: *default
  database: app_test

production:
  <<: *default
  database: app_production
  username: app
  password: <%= ENV['APP_DATABASE_PASSWORD'] %>

Display confirmation

Container launch

docker-compose up -d

DB creation

docker-compose run web rake db:create

Connect to http: // localhost: 3000 and check the operation.