Docker swarm mode on Docker Desktop

Question

I've managed to run Docker Swam mode with multiple hosts with Docker Toolbox, but I am unable to create a swarm with Docker Desktop since it apparently only offers single node swarm.

Is there any way to get this working with Docker Desktop or is it not supported?

Answer 1

No. But yes. But actually no. But technically yes.

No. Docker Desktop does not support this. It manages a single docker node in a vm and has no capability to manage multiple dockers.

But yes. docker:dind is an image you can easily use to deploy multiple docker nodes as containers, and then swarm init / swarm join to create a swarm cluster hosted on docker. You can even swarm join the docker-desktop node to be the swarm manager which means you can communicate with your local docker desktop node to control the swarm.

But actually, no. Unless your use case is a very limited hello-world on swarm tutorial, there is no support for exposing ports from the dind-swarm to the host. Even if the host docker acts as the manager, overlay.networking that is required for ingress will require communications over:2377, :4789/udp, and:7946, and as the host is not part of its own overlay.networks, this will never work. So, communicating with tasks running on the swarm is basically impossible.

But technically yes. play-with-docker apparently runs docker swarms using dind. They do some heavy lifting to expose a restricted set of ports via l7 loadbalancers. Pretty cool. but not at all easy to do at home. If you have a spare Dell PowerEdge or equivalent blade server with 120+ cores just laying around, and want to expose it as a docker swarm rather than split it into VMS... perhaps this is a viable approach.