How to patch statefulset on kubernetes cluster and set imagePullPolicy

In addition to @Colwins answer, you should also add mandatory key name into container spec, otherwise you'll get does not contain declared merge key: name

So, you kubectl command should look like:

kubectl patch statefulset my-set -p '{"spec": {"template": {"spec":{"containers":[{"name":"nginx","imagePullPolicy":"Never"}]}}}}'

I think you are missing the template key in your command

kubectl patch statefulset my-set -p '{"spec": {"template": {"spec":{"containers":[{"name": "xxxxxxx", "imagePullPolicy":"IfNotPresent"}]}}}}'

The stateful set yaml looks something like this

apiVersion: apps/v1kind: StatefulSetmetadata:  name: webspec:  serviceName: "nginx"  replicas: 2  selector:    matchLabels:      app: nginx  template:    metadata:      labels:        app: nginx    spec:      containers:      - name: nginx        image: k8s.gcr.io/nginx-slim:0.8        ports:        - containerPort: 80          name: web        volumeMounts:        - name: www          mountPath: /usr/share/nginx/html  volumeClaimTemplates:  - metadata:      name: www    spec:      accessModes: [ "ReadWriteOnce" ]      resources:        requests:          storage: 1Gi

So the path to the containers field is

spec >> template >> spec >> containers