OpenShift for Developers, 2nd Edition

Chapter 10. Templates, Operators, and OpenShift Automation

You’ve used templates and Operators throughout this book. Both automate repetitive tasks. This chapter provides more detail about these two mechanisms and relates them to the principle of automation in OpenShift. Triggering builds and deployments when source code changes, restarting failed pods, and an Operator upgrading your application’s database server are all ways of delegating to software some of the toil of operating software.

An OpenShift template automates the creation of a set of resources so that it can describe, for example, an application’s components and then be repeatedly processed to deploy that application. An Operator also deploys an application and its resources, but an Operator continues to watch and govern those resources over their entire life cycle. The most advanced Operators turn their applications into managed services. You took steps in an administrator role to set up Operators for Pipelines and other services. But consider the process after that was done: back in your developer role, you selected and instantiated services in your Project without much concern for the details of their deployment and administration. The Operator created the resources, started the services, and kept them running so that you could use them in your application.

Templates

A template is a list of objects and the named parameters of their configuration. Each time OpenShift processes a template, it inserts values for ...