Jobs and CronJobs

Jobs

Working with Jobs is a bit different than working with Deployments. Create a Job using the following template:

kubectl apply -f - <<EOF
apiVersion: batch/v1
kind: Job
metadata:
  name: sleepy
spec:
  template:
    spec:
      containers:
      - name: resting
        image: busybox
        command: ["/bin/sleep"] 
        args: ["3"]
      restartPolicy: Never
EOF
job.batch/sleepy created

Check the Job

kubectl get job
NAME COMPLETIONS DURATION AGE
sleepy 0/1         3s     3s

kubectl describe jobs.batch sleepy
Name:             sleepy
Namespace:        default
Selector:         batch.kubernetes.io/controller-uid=97bb2f4b-b7de-4a8a-bc9a-180ad55d4a84
Labels:           batch.kubernetes.io/controller-uid=97bb2f4b-b7de-4a8a-bc9a-180ad55d4a84
                  batch.kubernetes.io/job-name=sleepy
                  controller-uid=97bb2f4b-b7de-4a8a-bc9a-180ad55d4a84
                  job-name=sleepy
Annotations:      <none>
Parallelism:      1
Completions:      1
Completion Mode:  NonIndexed
Suspend:          false
Backoff Limit:    6
Start Time:       Thu, 24 Oct 2024 00:41:56 +0200
Completed At:     Thu, 24 Oct 2024 00:42:06 +0200
Duration:         10s
Pods Statuses:    0 Active (0 Ready) / 1 Succeeded / 0 Failed

Play around with parallelism, activeDeadlineSeconds (change the sleep parameter too) and completions number (delete the job in between retries), how does that affect the number of concurrent pods running?

CronJobs

Create the CronJob:

kubectl apply -f - <<EOF
apiVersion: batch/v1
kind: CronJob
metadata:
  name: sleepy
spec:
  schedule: "*/2 * * * *" #<-- Add Linux style cronjob syntax
  jobTemplate: #<-- New jobTemplate and spec move
    spec:
      template: #<-- This and following lines move
        spec: #<-- four spaces to the right
          containers:
          - name: resting
            image: busybox
            command: ["/bin/sleep"]
            args: ["5"]
          restartPolicy: Never
EOF

Check the execution:

$ kubectl get cronjobs
NAME     SCHEDULE      TIMEZONE   SUSPEND   ACTIVE   LAST SCHEDULE   AGE
sleepy   */2 * * * *   <none>     False     0        <none>          11s

$ kubectl get jobs
NAME     STATUS     COMPLETIONS   DURATION   AGE
sleepy   Complete   1/1           10s        9m44s