Docker container deployment to mulitple nodes in a swarm cluster

Question

I have a swarm cluster of 6 worker nodes and 3 master nodes so a total of 9 nodes. I am having machines of different sizes in my swarm cluster. So there is a requirement that I need to deploy certain services (containers) on particular worker nodes as per the size of the node. I am aware we can have placement constraints in the docker-compose file and can specify the hostname.

Since I will be running 2 replicas of the service so swarm will create replicas on the same worker to which I have set the constraint. But I don't want the replicas to be running on the same worker node.

Can we have an option to specify multiple hostnames while setting the placement constraint? Please guide.

Answer 1

You can to combine some nodes by labels.

    docker node update --label-add ssd=fat_machine hostname1
    docker node update --label-add ssd=fat_machine hostname2

and define label in docker-compose

    constraints: [node.labels.ssd == fat_machine]