Docker - docker-compose.yml

Basic

version: "3"
services:
  web:
    # replace username/repo:tag with your name and image details
    image: username/repo:tag
    deploy:
      replicas: 5
      resources:
        limits:
          cpus: "0.1"
          memory: 50M
      restart_policy:
        condition: on-failure
    ports:
      - "80:80"
    networks:
      - webnet
networks:
  webnet:

where:

• web define the name of the service as web
• image: defines the image to pull
• replicas defines the number of instances to run
• limits limits each replica to use, at most, 10% of the CPU (across all cores), and 50MB of RAM.
• restart_policy defines that a replica must restart on failure
• ports map the port 80 on the host to web’s port 80. See Docker - Port
• webnet defines a load-balanced network that shares the port 80 (Internally, the containers themselves publish to web’s port 80 at an ephemeral port.). The default settings is a load-balanced overlay network.

From docker options to yaml

Theses options:

docker container run -d \
  --env DOKKU_HOSTNAME=dokku.me \
  --env DOKKU_HOST_ROOT=/var/lib/dokku/home/dokku \
  --env DOKKU_LIB_HOST_ROOT=/var/lib/dokku/var/lib/dokku \
  --name dokku \
  --publish 3022:22 \
  --publish 8080:80 \
  --publish 8443:443 \
  --volume /var/lib/dokku:/mnt/dokku \
  --volume /var/run/docker.sock:/var/run/docker.sock \
  dokku/dokku:0.34.4

Are equivalent to

version: "3.8"

services:
  dokku:
    image: dokku/dokku:0.34.4
    container_name: dokku
    ports:
      - "3022:22"
      - "8080:80"
      - "8443:443"
    volumes:
      - "/var/lib/dokku:/mnt/dokku"
      - "/var/run/docker.sock:/var/run/docker.sock"
    environment:
      DOKKU_HOSTNAME: dokku.me
      DOKKU_HOST_ROOT: /var/lib/dokku/home/dokku
      DOKKU_LIB_HOST_ROOT: /var/lib/dokku/var/lib/dokku
    restart: unless-stopped

Port

Port linkage

version: '2'

services:

  serviceName:
    ports:
      - "8080:8080"
      - "80:80"
      - ...

Network

version: '2'

services:

  serviceName:
    networks:
      - netWorkName

networks:

  networkName:
    driver: bridge

See: Network - Bridge Driver