Now, suppose that the workload in the previous section starts to overload each of our three Docker hosts. Without a load balancer such as our preceding Nginx setup, our application's performance will start to degrade. This may mean a lower quality of service to our application's users or being paged in the middle of the night to perform heroic systems operations. However, with a load balancer managing the connections to our applications, it is very simple to add more capacity to scale out the performance of our application.
As our application is already designed to be load balanced, our scale-out process is very simple. The next few steps form a typical workflow on how to add capacity to a load-balanced application:
First, provision new Docker hosts with the same base configuration as the first three in our Docker host pool. In this section, we will create two new Docker hosts, named
greenhost03andgreenhost04.The next step in our scale-out process is to...