statefulset unable to rollback if the pods are not in running state - openshift

Question

I have deployed mongo stateful pods with an auto rolling strategy and below is the template for it. The deployment is successful and the pods are into Running state.
- apiVersion: apps/v1beta1
kind: StatefulSet
metadata:
name: mongo
spec:
serviceName: "mongo"
podManagementPolicy: Parallel
replicas: 3
strategy:
type: Rolling
template:
metadata:
labels:
role: mongo
environment: test
spec:
terminationGracePeriodSeconds: 10
containers:
- name: mongo
image: mongo:4.0
imagePullPolicy: Always
command:
- mongod
- "--replSet"
- rs0
- "--bind_ip"
- 0.0.0.0
- "--smallfiles"
- "--noprealloc"
ports:
- containerPort: 27017
volumeMounts:
- name: mongo-persistent-storage
mountPath: /data/db
- name: mongo-sidecar
image: cvallance/mongo-k8s-sidecar
env:
- name: MONGO_SIDECAR_POD_LABELS
value: "role=mongo,environment=test"
updateStrategy:
type: RollingUpdate
I am trying to update the image of the mongo using the following set command,
oc set image statefulset/mongo mongo=mongo:4.2 -n mongo-replica
While trying to update the image, the pods are into "CrashLoopBackOff" error. I am expecting the pods to be auto rolled back to the previous running version.
But the pods are struck in "CrashLoopBackOff" error state. I want the pods to be rolled back to the previous running version. Any suggestions here would be appreciated.

Answer 1

Statefulset unfortunately don't have a Rollback, but you can warranty your services using the probes, having a well configure Liveness and Readiness probes the changed version will only take the place of the running version with the probes answering an ok status.
In that way only one of your 3 replicas will crash in a failure, and you can work on it to solve the problem or manually rollback your changes, but without losing the delivery of your service.
More detail about this you can see on the k8s documentation:
https://kubernetes.io/docs/concepts/workloads/controllers/statefulset/#forced-rollback
About the probes, you can get a good explanation about it here:
https://www.openshift.com/blog/liveness-and-readiness-probes