Getting Started

Verified against v1.9.0. Commands assume a running Kubernetes cluster and Helm v3.5+.

Prerequisites

• A Kubernetes cluster (a recent version; older docs cite 1.13+ as the floor due to CRD conversion).
• Helm v3.5 or newer.
• kubectl configured against the cluster.

Install

helm repo add openkruise https://openkruise.github.io/charts/
helm repo update
helm install kruise openkruise/kruise --version 1.9.0 \
  --namespace kruise-system --create-namespace

A first working setup

The shortest path that exercises the core feature is a CloneSet rolled with InPlaceIfPossible, watching the Pod stay alive through an image change.

1. Create a CloneSet.

   cat <<'EOF' | kubectl apply -f -
   apiVersion: apps.kruise.io/v1alpha1
   kind: CloneSet
   metadata:
     name: sample
   spec:
     replicas: 3
     selector:
       matchLabels:
         app: sample
     template:
       metadata:
         labels:
           app: sample
       spec:
         containers:
           - name: main
             image: nginx:1.25.0
     updateStrategy:
       type: InPlaceIfPossible
   EOF

2. Watch the Pods in one terminal.

   kubectl get pod -l app=sample -w

3. Change only the image, in another terminal.

   kubectl patch cloneset sample --type='merge' \
     -p '{"spec":{"template":{"spec":{"containers":[{"name":"main","image":"nginx:1.25.3"}]}}}}'

The Pods keep their names and IPs; the RESTARTS count rises while AGE does not reset, because the container restarts in place rather than the Pod being recreated.

Verify it works

Confirm both components are running:

kubectl -n kruise-system get deploy kruise-controller-manager
kubectl -n kruise-system get daemonset kruise-daemon

After the patch, inspect the in-place state annotation on a Pod:

kubectl get pod -l app=sample \
  -o jsonpath='{.items[0].metadata.annotations.apps\.kruise\.io/inplace-update-state}'

It records the revision and the per-container update state used to judge completion.

Where to go next

For production concerns such as HA, webhook hardening, feature gates, and per-CRD configuration, see the official Installation and CloneSet docs, and the InPlace Update concept page.