https://medium.com/@aevitas/continuous-integration-and-deployment-with-github-circleci-and-kubernetes-50405716de7c

Deploying an application is traditionally the most challenging part of the software delivery process. No two machines are the same, the guy who usually does the deployments is on vacation, and risk of disrupting production is ever looming. Without proper automation and safety checks, it can be a very daunting process.

In the modern, containerized world of applications, deployments can be more easily automated, with more safety checks, and with far fewer variables than before. Rather than deploying to a multitude of machines, each with their own configurations and dependencies, we can simply deploy our self-contained application as a container, and be confident it will run.