In this blog, we will see how to create Jobs and CronJobs on Kubernetes.

Do you know what is Jobs and CronJobs on Kubernetes?

If you don't know don't worry I will give you a quick review of Jobs and CronJobs in Kubernetes.

What Are Kubernetes Jobs?

Jobs are objects in Kubernetes that deploy a pod, run tasks to completion, and then stop. They do not run continuously like other Kubernetes objects.

Use cases:

  • One-time tasks
  • Batch data processing
  • Database migrations
  • Cleanup operations

First, here's a simple example of how to create Jobs on Kubernetes.

Create Jobs

To create a Job, first, create a manifest file job.yaml and copy the below content into it

apiVersion: batch/v1
kind: Job
metadata:
  name: job
spec:
  template:
    spec:
      containers:
      - name: container
        image: busybox
        command: ["echo", "Hello, Kubernetes!"]
      restartPolicy: Never

Run the following command to create a Job:

kubectl apply -f job.yaml

This will create a Job in the default namespace that runs the echo command on the busybox container and then gets terminated.

Check the Job:

kubectl get jobs

Check the logs:

kubectl get pods
kubectl logs <pod-name>

What Are Kubernetes CronJobs?

CronJobs are also a Kubernetes object that schedules tasks to run at specified times. The job will automatically start according to the schedule specified in the job.

Use cases:

  • Backups
  • Log rotation
  • Cleanup jobs
  • Scheduled reports

Create CronJobs

Now, let's see how to create CronJobs on Kubernetes.

To create a Job, first, create a manifest file cronjob.yaml and copy the below content into it

apiVersion: batch/v1
kind: CronJob
metadata:
  name: cronjob
spec:
  schedule: "*/1 * * * *"
  jobTemplate:
    spec:
      template:
        spec:
          containers:
          - name: container
            image: busybox
            command: ["echo", "Hello, Kubernetes!"]
          restartPolicy: Never

Run the following command to create a Job:

kubectl apply -f cronjob.yaml

This will create a CronJob on the default namespace which schedules the command to run every 1 minute and print “Hello, Kubernetes!”

Check CronJob activity:

kubectl get cronjobs
kubectl get jobs

Check the logs:

kubectl get pods
kubectl logs <pod-name>

Important Fields for CKA

These fields often appear in exam scenarios.

Jobs:

  • completions: how many times the Job must run successfully
  • parallelism: how many Pods run at the same time
  • backoffLimit: retry count before marking the Job as failed

CronJobs:

  • suspend: true to pause CronJobs
  • concurrencyPolicy:
    • Allow (default)
    • Forbid (do not run new Job if previous is still running)
    • Replace (kill old Job and run a new one)

Conclusion

In this blog, you have learned about how to create Jobs and CronJobs and how they run tasks on Kubernetes.

I hope this blog gives a basic understanding of Kubernetes Jobs and CronJobs.