Boost Kubernetes Deployments with OpenKruise’s Advanced StatefulSet

Background

When deploying applications with Deployment, pod IDs change frequently, making monitoring and ID‑bound services difficult. Using StatefulSet solves the ID issue but introduces a new problem: pods start sequentially, causing long startup times for large‑scale workloads.

OpenKruise Overview

OpenKruise (https://github.com/openkruise/kruise) extends Kubernetes with five improved controllers:

CloneSet – manages stateless applications with features such as in‑place update, configurable priority, and pre/post‑update hooks.

Advanced StatefulSet – adds in‑place update strategies (InPlaceIfPossible, InPlaceOnly) and supports parallel pod startup.

SidecarSet – injects and upgrades sidecar containers based on selectors.

UnitedDeployment – manages pods across multiple fault domains using multiple workloads.

BroadcastJob – runs a job on every node in the cluster.

Advanced StatefulSet extends the native StatefulSet by supporting both recreate and rolling‑update strategies, with two rolling‑update modes: InPlaceIfPossible (updates only the container image) and InPlaceOnly (forces in‑place updates, rejecting non‑image changes). It also allows parallel pod startup.

Deploying OpenKruise

The official installation guide is available at the project’s documentation. Below are the essential steps:

<code>wget https://github.com/openkruise/kruise/releases/download/v0.4.0/kruise-chart.tgz
 tar xf kruise-chart.tgz
 cd kruise
 helm install openkruise ./ -n kube-system</code>

OpenKruise is now at version v0.5.0 and can also be installed via Alibaba Cloud’s application catalog.

Detailed installation:

Obtain the Helm chart:

<code>helm repo add incubator http://aliacs-k8s-cn-beijing.oss-cn-beijing.aliyuncs.com/app/charts-incubator/
helm search repo ack-kruise
helm fetch incubator/ack-kruise
tar xf ack-kruise-0.5.0.tgz
cd ack-kruise</code>

Modify

values.yml

to use a private image repository and enable only the Advanced StatefulSet resource:

<code># Default values for kruise.

revisionHistoryLimit: 3

manager:
  log:
    level: "4"
  image:
    repository: hub.example.com/library/kruise-manager
    tag: v0.5.0
  resources:
    limits:
      cpu: 500m
      memory: 1Gi
    requests:
      cpu: 500m
      memory: 1Gi
  metrics:
    addr: localhost
    port: 8080
  custom_resource_enable: StatefulSet</code>

Only the image repository and

custom_resource_enable

fields are changed.

Install the chart:

<code>helm install ack-kruise -n kube-system ./</code>

After installation, five CRDs are created:

<code># kubectl get crds | grep kruise
broadcastjobs.apps.kruise.io
clonesets.apps.kruise.io
sidecarsets.apps.kruise.io
statefulsets.apps.kruise.io
uniteddeployments.apps.kruise.io</code>

A

kruise-system

namespace is created with a controller manager pod:

<code># kubectl get pods -n kruise-system
NAME                              READY   STATUS    RESTARTS   AGE
kruise-controller-manager-0       1/1     Running   0          55m</code>

Verify that the StatefulSet webhook is created and that unrelated mutating webhooks are disabled.

These webhooks are part of Kubernetes admission control; if they malfunction, requests can fail or be delayed.

Usage Example

Below is a sample manifest for an OpenKruise Advanced StatefulSet:

<code>apiVersion: apps.kruise.io/v1alpha1
kind: StatefulSet
metadata:
  name: demo-v1-guestbook-kruise
  labels:
    app.kubernetes.io/name: guestbook-kruise
    app.kubernetes.io/instance: demo-v1
spec:
  replicas: 3
  serviceName: demo-v1-guestbook-kruise
  selector:
    matchLabels:
      app.kubernetes.io/name: guestbook-kruise
      app.kubernetes.io/instance: demo-v1
  template:
    metadata:
      labels:
        app.kubernetes.io/name: guestbook-kruise
        app.kubernetes.io/instance: demo-v1
    spec:
      readinessGates:
      - conditionType: InPlaceUpdateReady
      containers:
      - name: guestbook-kruise
        image: openkruise/guestbook:v1
        imagePullPolicy: Always
        ports:
        - name: http-server
          containerPort: 3000
  podManagementPolicy: Parallel
  updateStrategy:
    type: RollingUpdate
    rollingUpdate:
      podUpdatePolicy: InPlaceIfPossible
      maxUnavailable: 3</code>

Deploying this manifest results in three running pods:

<code># kubectl get pods | grep demo-v1
demo-v1-guestbook-kruise-0   1/1   Running   0   62s
demo-v1-guestbook-kruise-1   1/1   Running   0   62s
demo-v1-guestbook-kruise-2   1/1   Running   0   62s</code>

Check the resource status:

<code># kubectl get sts.apps.kruise.io
NAME                       DESIRED   CURRENT   UPDATED   READY   AGE
demo-v1-guestbook-kruise   3         3         3         3       56s</code>

OpenKruise’s StatefulSet resource is identified as sts.apps.kruise.io .

For more details, refer to the official documentation links for Advanced StatefulSet and UnitedDeployment.