how to limit container running on different node use docker stack deploy

Question

I have three nodes in docker swarm (all nodes are manager) I want to run zookeeper cluster on these three nodes

my docker-compose file

version: '3.8'
services:
  zookeeper1:
    image: 'bitnami/zookeeper:latest'
    hostname: "zookeeper-1"
    ports:
      - '2181'
      - '2888'
      - '3888'
    volumes:
      - "zookeeper-1:/opt/bitnami/zookeeper/conf"
    environment:
      - ZOO_SERVER_ID=1
      - ZOO_SERVERS=0.0.0.0:2888:3888,zookeeper-2:2888:3888,zookeeper-3:2888:3888
      - ALLOW_ANONYMOUS_LOGIN=yes
    networks:
      - network_test
  zookeeper2:
    image: 'bitnami/zookeeper:latest'
    hostname: "zookeeper-2"
    ports:
      - '2181'
      - '2888'
      - '3888'
    volumes:
      - "zookeeper-2:/opt/bitnami/zookeeper/conf"
    environment:
      - ZOO_SERVER_ID=2
      - ZOO_SERVERS=zookeeper-1:2888:3888,0.0.0.0:2888:3888,zookeeper-3:2888:3888
      - ALLOW_ANONYMOUS_LOGIN=yes
    networks:
      - network_test
  zookeeper3:
    image: 'bitnami/zookeeper:latest'
    hostname: "zookeeper-3"
    ports:
      - '2181'
      - '2888'
      - '3888'
    volumes:
      - "zookeeper-3:/opt/bitnami/zookeeper/conf"
    environment:
      - ZOO_SERVER_ID=3
      - ZOO_SERVERS=zookeeper-1:2888:3888,zookeeper-2:2888:3888,0.0.0.0:2888:3888
      - ALLOW_ANONYMOUS_LOGIN=yes
    networks:
      - network_test

I use docker stack deploy to run, my expect is each zookeeper will run on different node, but sometimes one node will start two zookeeper conatiners

Does the docker stack deploy can have this feature??

thanks

Answer 1

To start a service on each available node in your Docker Swarm cluster you need to run it in global mode.

But, in your case because of the specific volumes for each Zookeeper you can use placement constraints to control the nodes a service can be assigned to. So you can add the following section to each Zookeeper service which will allow each instance to run on a different node:

services:
  ...
  zookeeper-1:
   ...
   deploy:
      placement:
        constraints:
          - node.hostname==node1