Container Service for Kubernetes:Create CronJob workloads for scheduled tasks

Use the console

1. Log on to the ACK console. In the left-side navigation pane, click Clusters.

2. On the Clusters page, find the cluster you want and click its name. In the left-side pane, choose Workloads > CronJobs.

3. On the CronJobs page, click Create from Image.

4. On the Basic Information wizard page, configure the basic parameters of the application. Then, click Next to go to the Container wizard page.

5. In the General section, enter registry.cn-hangzhou.aliyuncs.com/acs-sample/nginx:latest as the Image Name. In the Lifecycle section, enter /bin/sh in the Command box of the Start parameter, and enter ["-c", "echo 'starting...'; COUNTER=0; while [ $COUNTER -lt 5 ]; do sleep 2; COUNTER=$((COUNTER+1)); echo $COUNTER; done; echo 'finished'; exit 0"] in the Parameter box. Click Next to go to the Advanced wizard page.

   Important

   Before you pull the registry.cn-hangzhou.aliyuncs.com/acs-sample/nginx:latest image, you must enable Internet access for the cluster. If you select Configure SNAT for VPC when you create the cluster, the cluster has Internet access. If you do not select this option, see Enable an existing ACK cluster to access the Internet.

   

6. On the Advanced wizard page, you can configure the scheduling and job settings for the CronJob. In this example, set the scheduling rule to run every 2 minutes and keep other options as default. Then, click Create at the bottom of the page.

   

   Category	Parameter	Description
   CronJob	Schedule	You can specify a schedule on an hourly, daily, weekly, or monthly basis. You can also specify a cron expression. For more information about Cron expressions, see Cron Expressions.
   	Concurrency Policy	Specifies whether a new job can be created when the current job is not completed. Forbid: Skips the creation of a new job. This option is suitable for scenarios where jobs must run in a specific order or depend on each other. Allow: Allows concurrent execution and directly creates a new job. This option is suitable for scenarios where jobs do not affect each other. Replace: Terminates the current Job and creates a new job. This option is suitable for scenarios where the latest execution results are required.
   	Job History	The number of successful and failed jobs that the CronJob retains to avoid excessive historical records from occupying resources. Successful Jobs History Limit: The number of the latest successful jobs to retain. Failed Jobs History Limit: The number of the latest failed jobs to retain.
   Job Settings	Completions	jobTemplate.spec.completions, which specifies the number of pods that enter the completed state.
   	Parallelism	jobTemplate.spec.parallelism, which specifies the number of pods that can run concurrently.
   	Timeout	jobTemplate.spec.activeDeadlineSeconds, which specifies the maximum runtime of a single job. The Job is stopped immediately after the runtime exceeds this value, regardless of whether the job is completed. This option is suitable for jobs that have strict time requirements or may enter an infinite loop. The default value is 600 seconds (s).
   	BackoffLimit	jobTemplate.spec.backoffLimit: The maximum number of retries after a pod fails, which is the total number of failures for all pods. The default value is 6.
   	Restart	jobTemplate.spec.template.spec.restartPolicy, which specifies the restart policy after a pod fails. Never: After a container in the pod exits abnormally, the system attempts to restart the pod in place (without creating a new pod). The restart is not counted in spec.backoffLimit. On Failure: After a pod fails, the system creates a new pod to replace it.
   Labels, Annotations	Pod Labels	Add a label to each pod to which the workload belongs. All resources in the cluster, including workloads and services, are matched with pods by using labels. ACK adds a label in the format of app:(application name) to pods by default.
   	Pod Annotations	Add an annotation to each pod to which the workload belongs. Some features in ACK use annotations. You can configure the annotations when you use these features.

7. After the CronJob is created, you can see jobs created at 2-minute intervals in the console.

   

Use kubectl

1. Copy the following YAML file and save it as cronjob.yaml. The jobTemplate.spec section of the CronJob has the same format as the spec section of a job. The following example uses the job example in Create a Job.

apiVersion: batch/v1
kind: CronJob
metadata:
  name: example-cronjob
  labels:
    app: cronjob
spec:
  schedule: "*/2 * * * *" # Run every 2 minutes
  concurrencyPolicy: Forbid # Forbid concurrent execution
  successfulJobsHistoryLimit: 3 # Retain the latest 3 successful jobs
  failedJobsHistoryLimit: 2     # Retain the latest 2 failed jobs
  jobTemplate:
    spec:
      completions: 1 # Stop the job after two pods are completed
      parallelism: 1 # Run only one pod at a time
      template:
        spec:
          containers:
          - name: counter
            image: anolis-registry.cn-zhangjiakou.cr.aliyuncs.com/openanolis/nginx:1.14.1-8.6
            command: 
            - /bin/sh
            - -c
            - |
              echo "starting...";
              COUNTER=0;
              while [ $COUNTER -lt 5 ]; do
                sleep 2;
                COUNTER=$((COUNTER+1));
                echo "${COUNTER}";
              done;
              echo "finished";
              exit 0
          restartPolicy: Never # Do not restart the pod

1. Run the following command to create a CronJob:

   kubectl apply -f cronjob.yaml

   Expected output:

   cronjob.batch/example-cronjob created

2. Wait for about 10 minutes and run the following command to check the job execution status:

   kubectl get job

   Expected output:

   NAME                       STATUS     COMPLETIONS   DURATION   AGE
   example-cronjob-2901**22   Complete   2/2           31s        5m13s
   example-cronjob-2901**23   Complete   2/2           31s        3m13s
   example-cronjob-2901**24   Complete   2/2           26s        73s