All of this can be found on my github repo here. After cloning you can follow the README.md instructions.

This post is mostly just to show how easy it is to get up and running with docker swarm mode and docker stack deploy.

Swarm Mode on Docker for Mac

This is an example of thumbor in docker swarm using docker stack deploy.

Initialize the swarm cluster

• docker swarm init

Let preemptively pull the docker images we will be using for the demo.

• docker pull apsl/thumbor-nginx
• docker pull apsl/thumbor

*Note: You can skip the above pull steps, but this will cause your services to take longer to start on the first deploy as it will need to pull down the images at deploy time.

Using the compose file in the repo let’s deploy the services.

• docker stack deploy -f docker-compose.yml img

Display a list of service running.

• docker service ls

Test our new dynamic image resizing service which has nginx in front of it.

• Visit http://localhost/unsafe/500x400/i.imgur.com/Q4FAyLw.png
• Enjoy the puppy!

Multi-host using Virtualbox

This example is the same as above but we will use multiple VMs to show how easy it is to cluster boxes. This requires docker-machine and virtualbox to be pre-installed.

We will start by using docker-machine to provision a manager for the swarm.

• docker-machine create --driver virtualbox manager

Now let’s provision 3 more boxes that will be our worker nodes.

• docker-machine create --driver virtualbox worker1
• docker-machine create --driver virtualbox worker2
• docker-machine create --driver virtualbox worker3

Now we can create the cluster

• eval $(docker-machine env manager)
• docker swarm init --advertise-addr eth1

Then run the resulting command in each worker. Here is an example output on my Mac.

• eval $(docker-machine env worker1)
• docker swarm join \ --token SWMTKN-1-0mfm860fo4snq5pt7zodvlcbh1irdbz4iixtz91kcs1my8d2hm-ets0olq240wa04agfqaf0tf9r \ 192.168.99.100:2377
• eval $(docker-machine env worker2)
• docker swarm join \ --token SWMTKN-1-0mfm860fo4snq5pt7zodvlcbh1irdbz4iixtz91kcs1my8d2hm-ets0olq240wa04agfqaf0tf9r \ 192.168.99.100:2377
• eval $(docker-machine env worker3)
• docker swarm join \ --token SWMTKN-1-0mfm860fo4snq5pt7zodvlcbh1irdbz4iixtz91kcs1my8d2hm-ets0olq240wa04agfqaf0tf9r \ 192.168.99.100:2377

Now that we have a swarm of 4 VM let’s connect back to the manager and deploy our img stack.

• eval $(docker-machine env manager)
• docker stack deploy -c docker-compose.yml img

docker-machine ls will give you the IP address of each node in the swarm cluster

You should be able to hit any of those IP address and enjoy the puppy

• Visit http://192.168.99.100/unsafe/500x400/i.imgur.com/Q4FAyLw.png

You can scale individual services by either modifying the docker-compose.yml file and running docker stack deploy -c docker-compose.yml img or running scaling commands as a one off docker service scale img_nginx=3

Visualizer for Docker Swarm

If you are a more visual person you can run manomarks docker swarm visualizer on the manager

• eval $(docker-machine env manager)
• docker run -it -d -p 8080:8080 -v /var/run/docker.sock:/var/run/docker.sock manomarks/visualizer
• Visit http://192.168.99.100:8080