Another advantage of having our Docker application load balanced is that we can use the same load-balancing techniques to update our application. Normally, operations engineers have to schedule downtime or a maintenance window in order to update an application deployed in production. However, as our application's traffic goes to a load balancer before it reaches our application, we can use this intermediate step to our advantage. In this section, we will employ a technique called blue-green deployments to update our running application with zero downtime.
Our current pool of hubuser/app:1.0.0 Docker containers is called our green Docker host pool because it actively receives requests from our NGINX load balancer. ...
