Creating a Job

Scenario

Jobs are short-lived and run for a certain time to completion. They can be executed immediately after being deployed. It is completed after it exits normally (exit 0).

A job is a resource object that is used to control batch tasks. It is different from a long-term servo workload (such as Deployment and StatefulSet).

A job is started and terminated at specific times, while a long-term servo workload runs unceasingly unless being terminated. The pods managed by a job automatically exit after successfully completing the job based on user configurations. The success flag varies according to the spec.completions policy.

• One-off jobs: A single pod runs once until successful termination.
• Jobs with a fixed success count: N pods run until successful termination.
• A queue job is considered completed based on the global success confirmed by the application.

Prerequisites

Resources have been created. For details, see Creating a Node. If clusters and nodes are available, you need not create them again.

Using the CCE Console

1. Log in to the CCE console.
2. Click the cluster name to go to the cluster console, choose Workloads in the navigation pane, and click Create Workload in the upper right corner.
3. Set basic information about the workload.
   Basic Info

   • Workload Type: Select Job. For details about workload types, see Overview.
   • Workload Name: Enter the name of the workload. Enter 1 to 63 characters starting with a lowercase letter and ending with a lowercase letter or digit. Only lowercase letters, digits, and hyphens (-) are allowed.
   • Namespace: Select the namespace of the workload. The default value is default. You can also click Create Namespace to create one. For details, see Creating a Namespace.
   • Pods: Enter the number of pods of the workload.
   Container Settings

   • Container Information
     Multiple containers can be configured in a pod. You can click Add Container on the right to configure multiple containers for the pod.

     • Basic Info: Configure basic information about the container.

       Parameter	Description
       Container Name	Name the container.
       Pull Policy	Image update or pull policy. If you select Always, the image is pulled from the image repository each time. If you do not select Always, the existing image of the node is preferentially used. If the image does not exist, the image is pulled from the image repository.
       Image Name	Click Select Image and select the image used by the container. To use a third-party image, see Using Third-Party Images.
       Image Tag	Select the image tag to be deployed.
       CPU Quota	Request: minimum number of CPU cores required by a container. The default value is 0.25 cores. Limit: maximum number of CPU cores available for a container. Do not leave Limit unspecified. Otherwise, intensive use of container resources will occur and your workload may exhibit unexpected behavior. If Request and Limit are not specified, the quota is not limited. For more information and suggestions about Request and Limit, see Setting Container Specifications.
       Memory Quota	Request: minimum amount of memory required by a container. The default value is 512 MiB. Limit: maximum amount of memory available for a container. When memory usage exceeds the specified memory limit, the container will be terminated. If Request and Limit are not specified, the quota is not limited. For more information and suggestions about Request and Limit, see Setting Container Specifications.
       (Optional) GPU Quota	Configurable only when the cluster contains GPU nodes and the gpu-device-plugin add-on is installed. All: The GPU is not used. Dedicated: GPU resources are exclusively used by the container. Shared: percentage of GPU resources used by the container. For example, if this parameter is set to 10%, the container uses 10% of GPU resources. For details about how to use GPU in the cluster, see Default GPU Scheduling in Kubernetes.
       (Optional) Privileged Container	Programs in a privileged container have certain privileges. If Privileged Container is enabled, the container is assigned privileges. For example, privileged containers can manipulate network devices on the host machine and modify kernel parameters.
       (Optional) Init Container	Indicates whether to use the container as an init container. The init container does not support health check. An init container is a special container that runs before other app containers in a pod are started. Each pod can contain multiple containers. In addition, a pod can contain one or more Init containers. Application containers in a pod are started and run only after the running of all Init containers completes. For details, see Init Container.

     • (Optional) Lifecycle: Configure operations to be performed in a specific phase of the container lifecycle, such as Startup Command, Post-Start, and Pre-Stop. For details, see Setting Container Lifecycle Parameters.
     • (Optional) Environment Variables: Set variables for the container running environment using key-value pairs. These variables transfer external information to containers running in pods and can be flexibly modified after application deployment. For details, see Setting an Environment Variable.
     • (Optional) Data Storage: Mount local storage or cloud storage to the container. The application scenarios and mounting modes vary with the storage type. For details, see Storage.
       

       If the workload contains more than one pod, EVS volumes cannot be mounted.

     • (Optional) Logging: Report container stdout streams to AOM by default and require no manual settings. You can manually configure the log collection path. For details, see Using ICAgent to Collect Container Logs.

       To disable the standard output of the current workload, add the annotation kubernetes.AOM.log.stdout: [] in Labels and Annotations. For details about how to use this annotation, see Table 1.

   • Image Access Credential: Select the credential used for accessing the image repository. The default value is default-secret. You can use default-secret to access images in SWR. For details about default-secret, see default-secret.
   • (Optional) GPU: All is selected by default. The workload instance will be scheduled to the node with the specified GPU graphics card type.
   (Optional) Advanced Settings

   • Labels and Annotations: Add labels or annotations for pods using key-value pairs. After entering the key and value, click Confirm. For details about how to use and configure labels and annotations, see Labels and Annotations.

   • Job Settings
     • Parallel Pods: Maximum number of pods that can run in parallel during job execution. The value cannot be greater than the total number of pods in the job.
     • Timeout (s): Once a job reaches this time, the job status becomes failed and all pods in this job will be deleted. If you leave this parameter blank, the job will never time out.
   • Network Configuration:
     • Pod ingress/egress bandwidth limitation: You can set ingress/egress bandwidth limitation for pods. For details, see Configuring QoS Rate Limiting for Inter-Pod Access.

4. Click Create Workload in the lower right corner.

Using kubectl

A job has the following configuration parameters:

• spec.template: has the same schema as a pod.
• RestartPolicy: can only be set to Never or OnFailure.
• For a single-pod job, the job ends after the pod runs successfully by default.
• .spec.completions: indicates the number of pods that need to run successfully to end a job. The default value is 1.
• .spec.parallelism: indicates the number of pods that run concurrently. The default value is 1.
• spec.backoffLimit: indicates the maximum number of retries performed if a pod fails. When the limit is reached, the pod will not try again.
• .spec.activeDeadlineSeconds: indicates the running time of pods. Once the time is reached, all pods of the job are terminated. The priority of .spec.activeDeadlineSeconds is higher than that of .spec.backoffLimit. That is, if a job reaches the .spec.activeDeadlineSeconds, the spec.backoffLimit is ignored.

Based on the .spec.completions and .spec.Parallelism settings, jobs are classified into the following types.

The following is an example job, which calculates π till the 2000^th digit and prints the output.

apiVersion: batch/v1
kind: Job
metadata:
  name: myjob
spec:
  completions: 50        # 50 pods need to be run to finish a job. In this example, π is printed for 50 times.
  parallelism: 5        # 5 pods are run in parallel.
  backoffLimit: 5        # The maximum number of retry times is 5.
  template:
    spec:
      containers:
      - name: pi
        image: perl
        command: ["perl",  "-Mbignum=bpi", "-wle", "print bpi(2000)"]
      restartPolicy: Never
      imagePullSecrets:
        - name: default-secret

Description

• apiVersion: batch/v1 indicates the version of the current job.
• kind: Job indicates that the current resource is a job.
• restartPolicy: Never indicates the current restart policy. For jobs, this parameter can only be set to Never or OnFailure. For other controllers (for example, Deployments), you can set this parameter to Always.

Run the job.

1. Start the job.

   [root@k8s-master k8s]# kubectl apply -f myjob.yaml
   job.batch/myjob created

2. View the job details.

   kubectl get job

   [root@k8s-master k8s]# kubectl get job
   NAME    COMPLETIONS   DURATION   AGE
   myjob   50/50         23s        3m45s

   If the value of COMPLETIONS is 50/50, the job is successfully executed.

3. Query the pod status.

   kubectl get pod

   [root@k8s-master k8s]# kubectl get pod
   NAME          READY   STATUS      RESTARTS   AGE
   myjob-29qlw   0/1     Completed   0          4m5s
   ...

   If the status is Completed, the job is complete.

4. View the pod logs.

   kubectl logs

   # kubectl logs myjob-29qlw
   3.1415926535897932384626433832795028841971693993751058209749445923078164062862089986280348253421170679821480865132823066470938446095505822317253594081284811174502841027019385211055596446229489549303819644288109756659334461284756482337867831652712019091456485669234603486104543266482133936072602491412737245870066063155881748815209209628292540917153643678925903600113305305488204665213841469519415116094330572703657595919530921861173819326117931051185480744623799627495673518857527248912279381830119491298336733624406566430860213949463952247371907021798609437027705392171762931767523846748184676694051320005681271452635608277857713427577896091736371787214684409012249534301465495853710507922796892589235420199561121290219608640344181598136297747713099605187072113499999983729780499510597317328160963185950244594553469083026425223082533446850352619311881710100031378387528865875332083814206171776691473035982534904287554687311595628638823537875937519577818577805321712268066130019278766111959092164201989380952572010654858632788659361533818279682303019520353018529689957736225994138912497217752834791315155748572424541506959508295331168617278558890750983817546374649393192550604009277016711390098488240128583616035637076601047101819429555961989467678374494482553797747268471040475346462080466842590694912933136770289891521047521620569660240580381501935112533824300355876402474964732639141992726042699227967823547816360093417216412199245863150302861829745557067498385054945885869269956909272107975093029553211653449872027559602364806654991198818347977535663698074265425278625518184175746728909777727938000816470600161452491921732172147723501414419735685481613611573525521334757418494684385233239073941433345477624168625189835694855620992192221842725502542568876717904946016534668049886272327917860857843838279679766814541009538837863609506800642251252051173929848960841284886269456042419652850222106611863067442786220391949450471237137869609563643719172874677646575739624138908658326459958133904780275901

Related Operations

After a one-off job is created, you can perform operations listed in Table 2.