Ruby on Rails Docker Development Setup

docker-compose.postgres.yml

version: '2.3'

services:

  postgres:
    image: postgres:9.6
    hostname: postgres
    ports:
      - "5432:5432"
    volumes:
      - "./tmp:/var/lib/postgresql/data"
    environment:
      POSTGRES_USER: placeholder
      POSTGRES_PASSWORD: placeholder

docker-compose.yml

version: '2.3'

services:

  placeholder-app:
    build: .
    container_name: placeholder-app
    hostname: placeholder-app
    ports:
      - "3000:80"
    volumes:
      - .:/app
    environment:
      - RAILS_ENV=development
      - DATABASE_URL=postgres://placeholder:placeholder@172.17.0.1
      - MAIL_URL=smtp://172.17.0.1:1025 # @TODO support
      - ROOT_URL=http://localhost:3000 # @TODO support

Dockerfile

FROM ruby:2.4.3

RUN apt-get update -qq && apt-get install -y build-essential libpq-dev graphviz

RUN mkdir /app
WORKDIR /app
COPY . /app

RUN bundle install

ENV PORT=80
EXPOSE $PORT

CMD bin/rails server -b '0.0.0.0' -p $PORT