Docker Setup for Rails – 26 July 2021

.env for database (development)

POSTGRES_USER=postgres
POSTGRES_PASSWORD=ThereNeedsToBeOne
POSTGRES_DB=my_project_development

.env for web (development)

DATABASE_HOST=database

Add to .gitignore

# Environment variables
/.env/*

/public/packs
/public/packs-test
/node_modules
/yarn-error.log
yarn-debug.log*
.yarn-integrity

database.yml

default: &default
  adapter: postgresql
  encoding: unicode
  host: <%= ENV.fetch('DATABASE_HOST') %>
  username: <%= ENV.fetch('POSTGRES_USER') %>
  password: <%= ENV.fetch('POSTGRES_PASSWORD') %>
  database: <%= ENV.fetch('POSTGRES_DB') %>
  pool: 5
  variables:
    statement_timeout: 5000

development:
  <<: *default

# Warning: The database defined as "test" will be erased and
# re-generated from your development database when you run "rake".
# Do not set this db to the same as development or production.
test:
  <<: *default
  database: my_project_test

production:
  <<: *default

docker-compose.yml

version: '3'

services:

  app: &app
    build: .
    tmpfs:
      - /tmp

  backend: &backend
    <<: *app
    stdin_open: true
    tty: true
    volumes:
      - .:/usr/src/app:cached
      - rails_cache:/usr/src/app/tmp/cache
      - bundle:/usr/local/bundle
      - node_modules:/app/node_modules
      - packs:/app/public/packs
    env_file:
      - .env/development/database
      - .env/development/web
    environment:
      - WEBPACKER_DEV_SERVER_HOST=webpack-dev-server

  web:
    <<: *backend
    entrypoint: ./bin/docker-entrypoint.sh
    command: bundle exec rails server -b 0.0.0.0
    ports:
      - "3000:3000"
      - "4000:4000"

  webpack-dev-server:
    <<: *app
    command: ./bin/webpack-dev-server
    volumes:
      - .:/usr/src/app:cached
      - bundle:/usr/local/bundle
      - node_modules:/app/node_modules
      - packs:/app/public/packs
    ports:
      - "3035:3035"
    environment:
      - WEBPACKER_DEV_SERVER_HOST=0.0.0.0

  database:
    image: postgres
    env_file:
      - .env/development/database
    volumes:
      - db_data:/var/lib/postgresql/data

  selenium_chrome:
    image: selenium/standalone-chrome-debug:3.141.59
    ports:
      - "5900:5900"

volumes:
  db_data:
  rails_cache:
  bundle:
  node_modules:
  packs:

docker-entrypoint.sh

#!/bin/sh
set -e

if [ -f tmp/pids/server.pid ]; then
  rm tmp/pids/server.pid
fi

exec bundle exec "$@"

Dockerfile

FROM ruby:2.7.4

LABEL maintainer="name@email.com"

# Allow use of https
RUN apt-get update -yqq && apt-get install -yqq --no-install-recommends \
  apt-transport-https

# Get recent Node
RUN curl -sL https://deb.nodesource.com/setup_14.x | bash -

# Get latest yarn
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

# Install packages
RUN apt-get update -yqq && apt-get install -yqq --no-install-recommends \
  nodejs \
  yarn

WORKDIR /usr/src/app