4.3 Additional Labs on Application Migration and Modernization Techlab

4.3.1 Operators

Mon, 01 Jan 0001 00:00:00 +0000

Operators are a way to package, deploy and manage Kubernetes-native applications. Kubernetes-native applications are applications that are deployed in Kubernetes/OpenShift and managed via the Kubernetes/OpenShift API (kubectl/oc). Since the introduction of OpenShift 4, OpenShift itself uses several operators to manage the OpenShift cluster.

Note

Use the existing Namespace <username>-operator for this lab.

Introduction / Terms

To understand, what an operator is and how it works, we first look at the so-called controller, because operators are based on its concept.

4.3.2 Requests and Limits

Mon, 01 Jan 0001 00:00:00 +0000

In this lab, we are going to look at ResourceQuotas and LimitRanges. As OpenShift users, we are most certainly going to encounter the limiting effects that ResourceQuotas and LimitRanges impose.

Note

Use the existing Namespace <username>-resources for this lab.

Task 4.3.2.1: Check project setup

We first check that the project is ready for the lab.

Ensure that the LAB_USER environment variable is set.

echo $LAB_USER

If the result is empty, set the LAB_USER environment variable.

4.3.3 Jobs and Cronjobs

Mon, 01 Jan 0001 00:00:00 +0000

Jobs are different from normal Deployments: Jobs execute a time-constrained operation and report the result as soon as they are finished; think of a batch job. To achieve this, a Job creates a Pod and runs a defined command. A Job isn’t limited to create a single Pod, it can also create multiple Pods. When a Job is deleted, the Pods started (and stopped) by the Job are also deleted.