Jobs and CronJobs for batch processing in Kubernetes - Practice Problems & Coding Challenges

Challenge - 5 Problems

💻 Command Output

intermediate

Output of a Kubernetes Job status command

What is the output of the following command after the Job completes successfully?

kubectl get jobs batch-job -o jsonpath='{.status.succeeded}'

A 0

B Error: job not found

C null

D 1

💡 Hint

The .status.succeeded field shows how many pods completed successfully.

When a Kubernetes Job finishes successfully, the .status.succeeded field shows the count of successful pods, usually 1 for a single-run Job.

🧠 Conceptual

intermediate

Understanding CronJob schedule format

Which of the following CronJob schedule strings runs a job every day at 3:30 AM?

A 30 3 * * *

B 3 30 * * *

C 0 3 * * *

D 30 15 * * *

💡 Hint

Cron format is: minute hour day month weekday

The schedule '30 3 * * *' means at minute 30 of hour 3 every day.

❓ Configuration

advanced

Correct YAML for a Kubernetes Job with restartPolicy

Which YAML snippet correctly defines a Kubernetes Job with a pod restart policy of 'Never'?

A

apiVersion: batch/v1
kind: Job
metadata:
  name: example-job
spec:
  template:
    spec:
      containers:
      - name: example
        image: busybox
        command: ['echo', 'hello']
      restartPolicy: Always

B

apiVersion: batch/v1
kind: Job
metadata:
  name: example-job
spec:
  template:
    spec:
      containers:
      - name: example
        image: busybox
        command: ['echo', 'hello']
      restartPolicy: Never

C

apiVersion: batch/v1
kind: Job
metadata:
  name: example-job
spec:
  restartPolicy: Never
  template:
    spec:
      containers:
      - name: example
        image: busybox
        command: ['echo', 'hello']

D

apiVersion: batch/v1
kind: Job
metadata:
  name: example-job
spec:
  template:
    spec:
      containers:
      - name: example
        image: busybox
        command: ['echo', 'hello']

💡 Hint

The restartPolicy must be under spec.template.spec and set to 'Never' for Jobs.

In Kubernetes Jobs, restartPolicy is set inside the pod template spec. 'Never' means pods won't restart on failure.

❓ Troubleshoot

advanced

Troubleshooting a CronJob that never runs

A CronJob is created with schedule '0 25 * * *'. What is the likely reason it never runs?

A The CronJob needs a manual trigger to start the first run.

B The minute field '0' is invalid; minutes must be 1-59.

C The hour field '25' is invalid; hours must be 0-23.

D The CronJob requires a restartPolicy of Always to run.

💡 Hint

Check the valid ranges for cron schedule fields.

Cron schedules use 0-23 for hours. '25' is invalid, so the job never triggers.

🔀 Workflow

expert

Order the steps to create and verify a Kubernetes CronJob

Put these steps in the correct order to create and verify a Kubernetes CronJob that runs a batch task every hour.

A 1,2,3,4

B 2,1,3,4

C 1,3,2,4

D 3,1,2,4

💡 Hint

Think about writing, applying, then checking status and logs.

First write the manifest, then apply it, then check status, then verify pods and logs.