Jobs and CronJobs for batch processing in Kubernetes - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is a Kubernetes Job?

A Kubernetes Job runs a task to completion. It creates one or more pods and ensures they finish successfully. Once done, the Job stops.

beginner

What is a CronJob in Kubernetes?

A CronJob runs Jobs on a schedule, like a clock. It creates Jobs repeatedly at specified times, similar to a calendar alarm.

intermediate

How does a Job ensure a task completes successfully?

A Job creates pods and watches them. If a pod fails, the Job starts a new pod until the task finishes successfully.

beginner

What is the key field to set the schedule in a CronJob YAML?

The key field is spec.schedule. It uses cron format like "*/5 * * * *" to run every 5 minutes.

intermediate

What happens if a CronJob's previous Job is still running when the next schedule starts?

By default, Kubernetes may skip starting a new Job if the previous one is still running, to avoid overlap. This behavior can be controlled with concurrencyPolicy.

What does a Kubernetes Job do?

A Manages network traffic

B Runs continuously without stopping

C Schedules tasks repeatedly on a timer

D Runs a task to completion and stops

A Job runs a task and ensures it finishes successfully, then stops.

Which field defines the schedule for a CronJob?

A spec.schedule

B metadata.name

C spec.template

D spec.replicas

The schedule is set in spec.schedule using cron syntax.

What happens if a Job pod fails before completion?

A The pod restarts automatically without Job intervention

B The Job stops immediately

C The Job creates a new pod to retry

D The Job deletes itself

The Job controller creates new pods to retry until success.

What is the default behavior if a CronJob's previous Job is still running at the next schedule?

A Skip starting a new Job

B Start a new Job anyway

C Delete the old Job

D Send an alert

By default, Kubernetes skips starting a new Job to avoid overlap.

Which Kubernetes resource would you use to run a task every day at midnight?

A Job

B CronJob

C Deployment

D Service

CronJob runs Jobs on a schedule, such as daily at midnight.

Explain the difference between a Kubernetes Job and a CronJob.

Think about one-time tasks versus scheduled repeated tasks.

Describe how Kubernetes handles a Job pod failure during batch processing.

Focus on Job's retry mechanism.