How to terminate a pod based on the amount of PIDs in a container?

Question

Setup: Multi-server K8s cluster

I want to terminate a container/pod when the number of PIDs running in the container from a specific user is below a certain count. For example: If "user" has less than 15 PIDs running in the container, I want the container and pod to terminate so that it spins up a new copy. Ideally I would have a cronjob run in the cluster that queries the number of PIDs that user has running, and if it is below 15, terminate the pod. I don't know how to query the PIDs running inside a container from the outside. Any ideas that might work?

Answer 1

Did you mean you need a pod restart?

You can try this with livenessProbe as described here: https://kubernetes.io/docs/tasks/configure-pod-container/configure-liveness-readiness-startup-probes/

Example:

apiVersion: v1
kind: Pod
metadata:
  labels:
    test: liveness
  name: liveness-exec
spec:
  containers:
  - name: liveness
    image: k8s.gcr.io/busybox
    args:
    - /bin/sh
    - -c
    - touch /tmp/healthy; sleep 30; rm -f /tmp/healthy; sleep 600
    livenessProbe:
      exec:
        command:
        - cat
        - /tmp/healthy
      initialDelaySeconds: 5
      periodSeconds: 5

You can implement your logic in command for counting processes