Docker Compose file for ruby, postgres and redis

docker-compose.yml

version: '3'
services:
  app:
    build:
      context: ..
      dockerfile: .devcontainer/Dockerfile
      args:
        VARIANT: 2.6
        NODE_VERSION: "lts/*"
    volumes:
      - ..:/workspace:cached
    command: sleep infinity

    # Runs app on the same network as the database container, allows "forwardPorts" in devcontainer.json function.
    network_mode: service:db
  db:
    image: postgres:latest
    restart: unless-stopped
    volumes:
      - postgres-data:/var/lib/postgresql/data
      - ./create-db-user.sql:/docker-entrypoint-initdb.d/create-db-user.sql
    environment:
      POSTGRES_USER: postgres
      POSTGRES_DB: postgres
      POSTGRES_PASSWORD: postgres
  redis:
    image: redis:4.0.14-alpine
    network_mode: service:db  # <-- this is the line that took me an hour, so app can see redis
volumes:
  postgres-data:

Taken from: https://twitter.com/chacon/status/1426986360703963144?lang=en

Also, the Rails/PG example has this line in the Dockerfile:

ENV RAILS_DEVELOPMENT_HOSTS=".githubpreview.dev"

but that doesn't work in Rails 6, so you just need to add this to your development.rb file:

config.hosts << /[a-z0-9\-]+\.githubpreview\.dev/ # for codespaces

More Details: https://aaronblondeau.com/posts/november_2021/github-codespaces/

More Details: https://code.visualstudio.com/docs/remote/codespaces