docker swarm stack example

docker-compose.yml

version: "3.8"

services:
  web:
    image: httpd:2.4.55
    ports: 
      - 80:80
    networks:
      - frontend
    deploy:
      replicas: 10
      placement:
        constraints: [node.role == worker]
      restart_policy:
        condition: on-failure
  
  node:
    image: node:19-alpine3.16
    networks:
      - frontend
      - backend
    command: ["sleep", "10000"] # this is only to force keep the conotainer running since there is no actual app code
    deploy:
      replicas: 4
      placement:
        constraints: [node.role == worker]
      restart_policy:
        condition: on-failure
  
  db:
    image: postgres:15.2
    volumes:
      - db-data:/var/lib/postgresql/data
    environment:
      - POSTGRES_PASSWORD=mypass
    networks:
      - backend
    deploy:
      replicas: 1
      placement:
        constraints: [node.role == worker]
      restart_policy:
        condition: on-failure
  
  visualizer:
    image: bretfisher/visualizer
    ports:
      - 8080:8080
    stop_grace_period: 1m30s
    networks:
      - frontend
    volumes:
      - /var/run/docker.sock:/var/run/docker.sock
    deploy:
      placement:
        constraints: [node.role == manager]

networks:
  frontend:
    driver: bridge
  backend:
    driver: bridge

volumes:
  db-data: