[SOLVED] k8s CronJob loop on list of pods

Issue

I want to run a loop on the pods in specific namespace, however the trick is to do it in a cronJob,is it possible inline?

kubectl get pods -n foo

The trick here is after you get the list of the pods, I need to loop on then and delete each one by one with timeout of 15 seconde, is it possible to do it in cronJob?

apiVersion: batch/v1
kind: CronJob
metadata:
  name: restart
  namespace: foo
spec:
  concurrencyPolicy: Forbid
  schedule: "*/1 * * * *"
  jobTemplate:
    spec:
      backoffLimit: 2
      activeDeadlineSeconds: 600
      template:
        spec:
          serviceAccountName: pod-exterminator
          restartPolicy: Never
          containers:
            - name: kubectl
              image: bitnami/kubectl:1.22.3
              command:
                - 'kubectl'
                - 'get'
                - 'pods'
                - '--namespace=foo'

When running the above script it works, but when you want to run loop its get complicated, how can I do it inline?

Solution

In your case you can use something like this:

apiVersion: batch/v1
kind: CronJob
metadata:
  name: restart
  namespace: foo
spec:
  concurrencyPolicy: Forbid
  schedule: "*/1 * * * *"
  jobTemplate:
    spec:
      backoffLimit: 2
      activeDeadlineSeconds: 600
      template:
        spec:
          serviceAccountName: pod-exterminator
          restartPolicy: Never
          containers:
            - name: kubectl
              image: bitnami/kubectl:1.22.3
              command:
              - /bin/sh
              - -c
              - kubectl get pods -o name |  while read -r POD; do kubectl delete "$POD"; sleep 15; done

However, do you really need to wait 15 seconds? If you want to be sure that pod is gone before deleting next one, you can use --wait=true, so the command will become:

kubectl get pods -o name |  while read -r POD; do kubectl delete "$POD" --wait; done

Answered By - Andrew

Answer Checked By - David Marino (WPSolving Volunteer)