Simple docker for rails

docker-compose.yml

version: '3'
services:
  db:
    image: postgres
    volumes:
      - datavol:/var/lib/postgresql/data
  web:
    build: .
    command: bundle exec rails s -p 3000 -b '0.0.0.0'
    volumes:
      - .:/app_name
    ports:
      - "3000:3000"
    depends_on:
      - db
    stdin_open: true
    tty: true
volumes:
  datavol:

Dockerfile

FROM ruby:2.5.0
 
ENV LANG C.UTF-8
RUN apt-get update -qq && apt-get install -y build-essential libpq-dev nodejs
 
RUN mkdir /app_name
WORKDIR /app_name
ADD Gemfile /app_name/Gemfile
ADD Gemfile.lock /app_name/Gemfile.lock
RUN bundle install
COPY . /app_name

Gemfile

source 'https://rubygems.org'

gem 'rails'