Run a job by using a virtual node

Background information

When you use a virtual node, your Kubernetes cluster can provide greater computing capability and allow you to create pods as needed.

For example, you have a Kubernetes cluster with one managed Master node and two Worker nodes, and the specifications of each Worker node is 4 CPUs and 8 GB. Therefore, the specifications of the managed Kubernetes cluster is 8 CPUs and 16 GB.

To run an offline job with 16 CPUs and 32 GB to process data, you can schedule the job to a virtual node to save computing resources for nodes of the cluster.

Prerequisites

• A managed Kubernetes cluster is created. For more information, see Create a cluster of ACK Managed Edition.
• A virtual node is deployed in the managed Kubernetes cluster. For more information, see Virtual nodes.
• The tag virtual-node-affinity-injection: enabled is added to the target namespace. For more information, see Set a namespace tag to create a pod.

Procedure

1. Connect to a Kubernetes cluster by using kubectl. For more information, see Use kubectl to connect to a cluster.
2. Copy and paste the following codes to job.yaml and run the kubectl -n vk apply -f job.yaml command to deploy a job.

   kind: Job
   metadata:
     name: pi
   spec:
     template:
       spec:
         containers:
         - name: pi
           image: perl
           command: ["perl",  "-Mbignum=bpi", "-wle", "print bpi(2000)"]
           resources:
             requests:
               cpu: 16
               memory: 32Gi
         restartPolicy: Never
     backoffLimit: 4

3. Run the following command to view the pod running status.

   kubectl -n vk get pod -a

   NAME       READY     STATUS      RESTARTS   AGE
   pi-7cmwv   0/1       Completed   0          2m

   kubectl -n vk describe pod

   Name:               pi-7cmwv
   Namespace:          vk
   Priority:           0
   PriorityClassName:  <none>
   Node:               virtual-kubelet/
   ...
   Events:
     Type    Reason                 Age   From               Message
     ----    ------                 ----  ----               -------
     Normal  Scheduled              3m    default-scheduler  Successfully assigned vk/pi-7cmwv to virtual-kubelet
     Normal  SuccessfulMountVolume  2m    kubelet, eci       MountVolume.SetUp succeeded for volume "default-token-b2tff"
     Normal  Pulling                2m    kubelet, eci       pulling image "perl"
     Normal  Pulled                 2m    kubelet, eci       Successfully pulled image "perl"
     Normal  Created                2m    kubelet, eci       Created container
     Normal  Started                2m    kubelet, eci       Started container

   Note The pod on a virtual node is charged according to the specific amount of resources that you use.