Docker Swarm Cluster with docker-in-docker on MacOS

TL;DR

Docker-in-Docker dind can help you to run Docker Swarm cluster on your Macbook only with Docker for Mac (v1.12+). No VirtualBox, docker-machine, vagrant or other app is required.

The Beginning

One day, I’ve decided to try running Docker 1.12 Swarm cluster on my MacBook Pro. Docker team did a great job releasing Docker for Mac, and from that time I forgot all problems I used to have with boot2docker. I really like Docker for Mac: it’s fast, lightweight, tightly integrated with MacOS and significantly simplifies my life when working in changing network environment. The only missing thing is that it’s possible to create and work with single Docker daemon running inside xhyve VM. Shit! I want a cluster.

Of cause, it’s possible to create Swarm cluster with docker-machine tool, but it’s not MacOS friendly and requires to install additional VM software, like VirtualBox or Parallels (why? I already have xhyve!). I have different network for work office and home. At work I’m behind corporate proxy with multiple firewall filters. At home, of cause, life is better. docker-machine requires to create dedicated VMs for each environment and thus force me juggling with different shell scripts when I switch from one to another. It’s possible, but it’s not fun.

I just want to have multi-node Swarm cluster with Docker for Mac (and xhyve VM). As simple as it is.

I’m a lazy person and if there is an already existing solution, I will alway choose one, even if it’s not ideal. So, after googling for a while, I’ve failed to find any suitable solution or blog post. So, I’ve decided to create my own and share it with you.

The Idea

The basic idea is to use Docker for Mac for running Swam master and several Docker-in-Docker containers for running Swarm worker nodes.

First, lets init our Swarm master:

# init Swarm master 
$ docker swarm init

… keep Swarm join token:

# get join token 
$ SWARM_TOKEN=$(docker swarm join-token -q worker)

… and Docker xhyve VM IP:

# get Swarm master IP (Docker for Mac xhyve VM IP) 
$ SWARM_MASTER=$(docker info | grep -w 'Node Address' | awk '{print $3}')

… now let’s create 3 worker nodes and join these nodes to our cluster

# run NUM_WORKERS workers with SWARM_TOKEN 
$ NUM_WORKERS=3 
$ for i in $(seq "${NUM_WORKERS}"); do \
    docker run -d --privileged \
      --name worker-${i} \
      --hostname=worker-${i} \
      --publish ${i}2375:2375 \
      --volume $PWD/cdata/worker-${i}:/var/lib/docker \
      docker:1.12.1-dind 
    # join swarm cluster 
    docker --host=localhost:${i}2375 \
      swarm join --token ${SWARM_TOKEN} ${SWARM_MASTER}:2377 \
  done

Listing all our Swarm cluster nodes:

# list Swarm nodes :) 
$ docker node ls

… you should see something like this:

ID HOSTNAME STATUS AVAILABILITY MANAGER STATUS 1f6z8pioh3vuaz84gyp0biqt0 worker-2 Ready Active 35z72o6zjhs9u1h99lrwzvx5n worker-3 Ready Active d9ph5cmc604wp1vhhs754nnxx * moby Ready Active Leader dj3gnpv86uqrw4b9mo9ux4jb5 worker-1 Ready Active

That’s all folks! Now, you have running Swarm cluster on your Macbook and your Docker client is talking with Swarm master.

Nice tip:

You can use very nice Swarm visualizer by Mano Marks to see your Swarm cluster “in action”.

Run it with following command:

$ docker run -it -d -p 8080:8080 \
     -e HOST=localhost \
     -v /var/run/docker.sock:/var/run/docker.sock \
     manomarks/visualizer

And you should be able to see something like this (after you deploy some demo app):

Originally published at blog.terranillius.com.