README.md

Basic Example

Basic Compose configuration for dockerizing a simple Ruby on Rails/SQLite app. I assume using a debian-based image in the Dockerfile commands.

• Dockerfile
• docker-compose.yml

Dockerfile

Choose ruby version from the docker images

FROM ruby:2.5

Install Node.js

RUN apt-get update -qq && \
    apt-get install -y build-essential nodejs

Create the app working directory

WORKDIR /app

Add rails user and give it ownership of the app directory
The user has a home directory, the default 1000 UID and belongs to a group with the same name

RUN useradd -u 1000 -Um rails && \
    chown -R rails:rails /app

Set rails as the default user

USER rails

docker-compose.yml

Choose compose version

version: '3'

Set a volume for the gem bundle

volumes:
  app_bundle:

Configure the web service

services:
  web:
    # build the app image from the Dockerfile in the working dir
    build: .
    # start the server binding to all interfaces
    command: rails s -b 0.0.0.0 -p 3000
    # send the right signal to the rails server when stopping the container
    stop_signal: SIGINT
    volumes:
      # bind the working dir on the host machine to the one in the container
      - .:/app
      # use the volume for storing the bundle
      - app_bundle:/usr/local/bundle
    # expose rails server to the host machine
    ports:
      - 3000:3000
    # try restarting the service on failure
    restart: on-failure