# A local Swarm cluster made of Docker-in-Docker nodes: 1 master + 3 workers
x-node: &node
  image: docker:dind
  privileged: true            # required to run a Docker daemon inside a container
  environment:
    DOCKER_TLS_CERTDIR: ""    # plain TCP on port 2375 (no TLS), fine for a local playground

services:
  master:
    <<: *node
    hostname: master
    ports:
      - "127.0.0.1:2375:2375" # Docker API of the master, for the host's CLI
  worker-1:
    <<: *node
    hostname: worker-1
  worker-2:
    <<: *node
    hostname: worker-2
  worker-3:
    <<: *node
    hostname: worker-3
  gateway:                    # relays the ports of the services deployed on the Swarm, via master
    image: alpine/socat
    entrypoint: ["sh", "-c"]
    command:
      - |
        for port in 9443 8889 8890; do
          socat TCP-LISTEN:$$port,fork,reuseaddr TCP:master:$$port &
        done
        wait
    ports:
      - "9443:9443"           # Portainer
      - "8889:8889"           # ports of the stacks deployed later in the lecture
      - "8890:8890"