What is CronJob and How to Use it in Kubernetes Cluster

The Cronjob is running in Kubernetes like a Linux or Windows Cron schedule, this post will walk you through to understand the Cron Jobs and configure your Kubernetes cluster.

A CronJob can creates Jobs on a repeating schedule as your have configured in the K8S cluster. And its performing regular scheduled actions such as backups, report generation, and so on

Create a YAML file with CronJob code: hello-cronjob.yaml

apiVersion: batch/v1

kind: CronJob

metadata:

  name: hello-world

spec:

  schedule: "*/10 * * * *"

  jobTemplate:

    spec:

      template:

        spec:

          containers:

          - name: hello-world

            image: hello-world-text:1.20.1

            command:

            - /bin/sh

            - -c

            - date; echo Hello-World from the K8S cluster

          restartPolicy: OnFailure

Execute the YAML code (hello-cronjob.yaml) using the command below,

$ kubectl create -f ./hello-cronjob.yaml



cronjob "hello-world" created

After creating the cron job, if you want to view the running CronJob with the command below,

$ kubectl get cronjob hello-world

And also, watch the running jobs which is triggered by CronJob around 10 minutes:

$ kubectl get jobs --watch



NAME                DESIRED   SUCCESSFUL   AGE

hello-world-206356    1         1         2s

If you would like to delete the CronJob and job use the command below, 

$ kubectl delete cronjob hello-world



cronjob "hello-world" deleted

This stops new jobs from being created. However, running jobs won't be stopped,  and no jobs or their pods will be deleted. To clean up those jobs and pods, you need to list all jobs created by the cron job, and delete them all.

$ kubectl delete jobs hello-world-206356 



job "hello-world-206356" deleted