I am testing lifecycle hooks, and post-start works pretty well, but I think pre-stop never gets executed. There is another answer, but it is not working, and actually if it would work, it would contradict k8s documentation. So, from the docs:

PreStop

This hook is called immediately before a container is terminated due to an API request or management event such as liveness probe failure, preemption, resource contention and others. A call to the preStop hook fails if the container is already in terminated or completed state.

So, the API request makes me think I can simply do kubectl delete pod POD, and I am good.

More from the docs (pod shutdown process):

1.- User sends command to delete Pod, with default grace period (30s)

2.- The Pod in the API server is updated with the time beyond which the Pod is considered “dead” along with the grace period.

3.- Pod shows up as “Terminating” when listed in client commands

4.- (simultaneous with 3) When the Kubelet sees that a Pod has been marked as terminating because the time in 2 has been set, it begins the pod shutdown process.

4.1.- If one of the Pod’s containers has defined a preStop hook, it is invoked inside of the container. If the preStop hook is still running after the grace period expires, step 2 is then invoked with a small (2 second) extended grace period.

4.2.- The container is sent the TERM signal. Note that not all containers in the Pod will receive the TERM signal at the same time and may each require a preStop hook if the order in which they shut down matters.

...

So, since when you do kubectl delete pod POD, the pod gets on Terminating, I assume I can do it.

From the other answer, I can't do this, but the way is to do a rolling-update. Well, I tried in all possible ways and it didn't work either.

My tests:

I have a deployment:

apiVersion: extensions/v1beta1
kind: Deployment
metadata:
  name: my-deploy
spec:
  replicas: 1
  template:
    metadata:
      name: lifecycle-demo
      labels:
        lifecycle: demo
    spec:
      containers:
      - name: nginx
        image: nginx
        lifecycle:
          postStart:
            exec:
              command:
              - /bin/sh 
              - -c
              - echo "Hello at" `date` > /usr/share/post-start
          preStop:
            exec:
              command:
              - /bin/sh"
              - -c
              - echo "Goodbye at" `date` > /usr/share/pre-stop
        volumeMounts:
        - name: hooks
          mountPath: /usr/share/
      volumes:
      - name: hooks
        hostPath:
          path: /usr/hooks/

I expect the pre-stop and post-start files to be created in /usr/hooks/, on the host (node where the pod is running). post-start is there, but pre-stop, never.

• I tried kubectl delete pod POD, and it didn't work.
• I tried kubectl replace -f deploy.yaml, with a different image, and when I do kubectl get rs, I can see the new replicaSet created, but the file isn't there.
• I tried kubectl set image ..., and again, I can see the new replicaSet created, but the file isn't there.
• I even tried putting them in a completely separated volumes, as I thought may be when I kill the pod and it gets re-created it re-creates the folder where the files should be created, so it deletes the folder and the pre-stop file, but that was not the case. Note: It always get re-created on the same node. I made sure on that.

What I have not tried is to bomb the container and break it by setting low CPU limit, but that's not what I need.

Any idea what are the circumstances under which preStop hook would get triggered?