Automatic proxified docker setup demo

What is this?

This is a demo using:

• docker
• docker-compose for composition
• consul for service discovery
• registrator to automatically feed consul with new containers
• tutum/hello-world as the demo application

How to run

First, launch the consul/registrator base infrastructure with:

$ docker-compose -f consul.yml up -d

Then launch the hello-world application with:

$ docker-compose -f hello.yml up -d

You could also launch both stacks in one go with:

$ docker-compose -f consul.yml -f hello.yml up -d

What is there to see?

Once the stacks are started, you can view:

• the consul dashboard at http://consul-admin.127.0.0.1.xip.io
• the haproxy dashboard at http://proxy-admin.127.0.0.1.xip.io
• the running application at http://hello-dev.127.0.0.1.xip.io

Scale the app

If you type:

$ docker-compose -f hello.yml scale web=2

You will see:

• A new node added to the consul dashboard
• A new backend added to the haproxy dashboard
• A changing ID when refreshing the application page

Health checking

Health checking is implemented at two levels in this stack:

• haproxy checks that port 80 of each member is up
• consul checks that the node is up and that / returns a 200 status

If either check fails, the node will not be proxified.

You can test the HTTP check with:

$ docker-compose -f hello.yml scale web=3
$ docker exec -ti $(basename $PWD)_web_2 pkill php-fpm

This will kill the php-fpm master process of the second container:

• The web_2 node will be shown in error in the consul dashboard
• The web_2 node will not appear anymore in the haproxy dashboard
• The service will still run on the two other instances

To fix it, kill the container and scale again:

$ docker rm -f $(basename $PWD)_web_2
$ docker-compose -f hello.yml scale web=3

TODO

• Test with an overlay network and:

  • get rid of links
  • use consul DNS instead of links

• Test on swarm

• Port to an AWS ECS stack with CloudFormation