That's what I do:

1. Deploy a stateful set. The pod will always exit with an error to provoke a failing pod in status CrashLoopBackOff: kubectl apply -f error.yaml
2. Change error.yaml (echo a => echo b) and redeploy stateful set: kubectl apply -f error.yaml
3. Pod keeps the error status and will not immediately redeploy but wait until the pod is restarted after some time.

Requesting pod status:

$ kubectl get pod errordemo-0
NAME          READY   STATUS             RESTARTS   AGE
errordemo-0   0/1     CrashLoopBackOff   15         59m

error.yaml

apiVersion: apps/v1
kind: StatefulSet
metadata:
  name: errordemo
  labels:
    app.kubernetes.io/name: errordemo
spec:
  serviceName: errordemo
  replicas: 1
  selector:
    matchLabels:
      app.kubernetes.io/name: errordemo
  template:
    metadata:
      labels:
        app.kubernetes.io/name: errordemo
    spec:
      containers:
        - name: demox
          image: busybox:1.28.2
          command: ['sh', '-c', 'echo a; sleep 5; exit 1']
      terminationGracePeriodSeconds: 1

Questions

How can I achieve an immediate redeploy even if the pod has an error status? I found out these solutions but I would like to have a single command to achieve that (In real life I'm using helm and I just want to call helm upgrade for my deployments):

• Kill the pod before the redeploy
• Scale down before the redeploy
• Delete the statefulset before the redeploy

Why doesn't kubernetes redeploy the pod at once?

• In my demo example I have to wait until kubernetes tries to restart the pod after waiting some time.
• A pod with no error (e.g. echo a; sleep 10000;) will be restarted immediately. That's why I set terminationGracePeriodSeconds: 1
• But in my real deployments (where I use helm) I also encountered the case that the pods are never redeployed. Unfortunately I cannot reproduce this behaviour in a simple example.