Development With Docker-Compose

Docker’s documentation leaves much to be desired as navigating it often becomes an exercise in CMD-fing. I often want to use docker-compose for a project to get it running locally as PoC before setting up my k8s cluster. But it usually takes me longer to get the ports and volumes sorted out than I would prefer.

Here’s a sample docker-compose.yml which marks a MongoDB container as a dependency for my web service. As all containers are accessible to each other based on the format <protocol>://<serviceName>:<port>, my web service can now ping the mongo service at mongodb://mongo:27017 and be assured that the mongo container is up and running when it does; with the mongo service’s container persisting its /data/db folder locally to my host machines working subdirectory ./data/db.

version: "3"
services:
  web:
    image: evanlouie/echoml
    ports:
      - 80:80
      - 3000:3000
      - 4000:4000
    depends_on:
      - mongo
      - redis
    environment:
      - NODE_ENV=production
  mongo:
    image: mongo
    ports:
      - 27017:27017
    volumes:
      - ./data/mongodb:/data/db
  redis:
    image: redis
    ports:
      - 6379:6379

Note: By default, containers can ping eachother via their service name, the depends_on marks one your services to require the listed ones to be started (doesn’t check if “ready”) before itself can start.

In order to make development easier, add ports mappings to expose the container ports to the host (<hostPort>:<containerPort>). Now you can develop locally on your host machine while having the mongo and redis containers exposed. In this example, mongo is accessible by the host via: mongodb://0.0.0.0:27017 and redis via redis://0.0.0.0:6379.

This is my default dev environment I run when developing locally (minus the web service). Exposing to my host persistent MongoDB, PostgreSQL, and MySQL databases as well as volatile redis cache:

version: "3"
services:
  mongo:
    image: mongo
    ports:
      - 27017:27017
    volumes:
      - ./data/mongodb:/data/db
  postgres:
    image: postgres
    ports:
      - 5432:5432
    volumes:
      - ./data/postgresql:/var/lib/postgresql/data
  mysql:
    image: mysql
    environment:
      - MYSQL_ROOT_PASSWORD=password
    ports:
      - 3306:3306
    volumes:
      - ./data/mysql:/var/lib/mysql
  redis:
    image: redis
    ports:
      - 6379:6379

LA(MMP)P stack? Sure!:

version: "3"
services:
  php:
    image: php:apache
    ports:
      - 9000:80
    volumes:
      - ./:/var/www/html
  mongo:
    image: mongo
    ports:
      - 27017:27017
    volumes:
      - ./data/mongodb:/data/db
  postgres:
    image: postgres
    environment:
      - POSTGRES_PASSWORD=password
    ports:
      - 5432:5432
    volumes:
      - ./data/postgresql:/var/lib/postgresql/data
  mysql:
    image: mysql
    environment:
      - MYSQL_ROOT_PASSWORD=password
    ports:
      - 3306:3306
    volumes:
      - ./data/mysql:/var/lib/mysql
  redis:
    image: redis
    ports:
      - 6379:6379