Creating the load balancer role

We created the Nginx and MySQL roles to serve the WordPress site. However, if we have to build a scalable site, we also need to add a load balancer to the mix. This load balancer will then act as an entry point for the incoming requests, and then spread the traffic across the available web servers. Let's consider the following scenario, where our fifanews site has become an instant hit. The traffic is growing exponentially, and the single web server approach that we have been using is showing cracks. We need to scale out horizontally and add more web servers. Once we start creating more web servers, we also need to have some mechanism to balance traffic across those. We have been tasked to create a haproxy role, which would discover all web servers in our cluster automatically and add to its configurations.

The following diagram explains this scenario with haproxy as a frontend, balancing the load across web servers in the backend. Haproxy is a widely...