haproxy-passenger-standalone-rolling-upgrades

This is repository is an example of how you can do zero downtime rolling upgrades with Haproxy using Phusion Passenger Standalone, with Ansible.

Overview

This zero downtime rolling upgrade, is accomplished by spinning up two seperate Passenger processes that sit behind an HAProxy load balancer. When a deploy is commencing, it will take down 1 process a a time, upgrade it, and reattach it back to the load balancer.

Getting Started

vagrant up

Startup Issues

Vagrant will complain about being unable to build guest additions, if you are using vb-guest.

After you get the error message, do the following:

vagrant ssh
sudo yum install kernel kernel-devel -y
exit

vagrant halt
vagrant up

Now Vagant should start to provision itself with Ansible.

Commands

./deploy.sh - run a deployment

./rollback.sh $rollback_release_version - rollback to a specific version, first argument is a integer.

In another terminal window, inside Vagrant, run:

sudo watch `sudo service haproxyctl show health`

To watch your rolling update live!

Live Demonstration

• localhost:8080 - Page that will poll an endpoint

Servers

• titanium - Passenger instance 1, runs on port 4000
• carbon - Passenger instance 2, runs on port 4001