Use OpenKruise to deploy cloud-native applications

Component architecture

Usage notes

OpenKruise provides controllers such as CloneSet, Advanced StatefulSet, and Advanced DaemonSet. The following section describes the features of commonly used controllers.

The following section compares the CloneSet, Advanced StatefulSet, and Advanced DaemonSet controllers of OpenKruise with the equivalent controllers provided by the Kubernetes community.

Install OpenKruise

Install OpenKruise through the Add-ons page

1. Log on to the ACK console.
2. In the left-side navigation pane of the ACK console, click Clusters.
3. On the Clusters page, find the cluster that you want to manage and click the name of the cluster or click Details in the Actions column. The details page of the cluster appears.
4. In the left-side navigation pane of the details page, choose Operations > Add-ons.
5. On the Add-ons page, click the Manage Applications tab. In the ack-kruise section, click Install.
   In the Note dialog box, confirm the component information and click OK.

Install OpenKruise through the App Catalog page

1. Log on to the ACK console.
2. In the left-side navigation pane of the ACK console, choose Marketplace > App Catalog.
3. On the Marketplace page, click the App Catalog tab, find and click ack-kruise.
4. On the ack-kruise page, click Deploy.
5. In the Deploy panel, select a cluster and namespace, and click Next.
6. On the Parameters wizard page, specify the parameters and click OK.

Use a CloneSet to deploy a stateless application

1. Create a CloneSet.
   1. Create a file named cloneset.yaml and copy the following code to the file.

      apiVersion: apps.kruise.io/v1alpha1
      kind: CloneSet
      metadata:
        name: demo-clone
      spec:
        replicas: 5
        selector:
          matchLabels:
            app: guestbook
        template: #The schema of the pod template is the same as that of a Deployment. 
          metadata:
            labels:
              app: guestbook
          spec:
            containers:
            - name: guestbook
              image: registry.cn-hangzhou.aliyuncs.com/kruise-test/guestbook:v1
              env:
              - name: test
                value: foo
        updateStrategy:
          type: InPlaceIfPossible     #We recommend that you perform an in-place upgrade instead of upgrading pods upon recreation. 
          maxUnavailable: 20%        #A maximum of 20% pods can be unavailable during the release. 
          inPlaceUpdateStrategy:
            gracePeriodSeconds: 3    #The graceful period specifies how long a pod stays in the Not-ready state before the controller performs an in-place upgrade on the pod. 

      • type: specifies the upgrade strategy. The following three strategies are supported:
        • ReCreate: The controller deletes the current pods and persistent volume claims (PVCs), and then creates new pods and PVCs.
        • InPlaceIfPossible: The controller attempts to perform an in-place upgrade. If the attempt fails, the controller upgrades the pods by recreating them.
        • InPlaceOnly: The controller is allowed to perform only in-place upgrades.
      • maxUnavailable: The maximum number of pods that can be unavailable during the upgrade process. You can specify an absolute value or a percentage value.
      • gracePeriodSeconds: The grace period specifies how long a pod stays in the Not-ready state before the controller performs an in-place upgrade on the pod.
   2. Make the cloneset.yaml file effective in the ACK cluster.

      kubectl create -f ./cloneset.yaml

      Expected output:

      cloneset.apps.kruise.io/demo-clone created

2. Query the status of the pods:

   kubectl get pod

   Expected output:

   NAME               READY   STATUS    RESTARTS   AGE
   demo-clone-5b9kl   1/1     Running   0          3s
   demo-clone-6xjdg   1/1     Running   0          3s
   demo-clone-bvmdj   1/1     Running   0          3s
   demo-clone-dm22s   1/1     Running   0          3s
   demo-clone-rbpg9   1/1     Running   0          3s

3. Query the CloneSet.

   kubectl get clone

   Expected output:

   NAME         DESIRED   UPDATED   UPDATED_READY   READY   TOTAL   AGE
   demo-clone   5         5         5               5       5       46s

   • DESIRED: the expected number of pods (spec.replicas).
   • UPDATED: the number of pods that are upgraded (status.updatedReplicas).
   • UPDATED_READY: the number of pods that are available after the pods are upgraded (status.updatedReadyReplicas).
   • READY: the total number of available pods (status.readyReplicas).
   • TOTAL: the total number of pods (status.replicas).

Use an Advanced StatefulSet to deploy a stateful application

1. Create an Advanced StatefulSet.
   1. Create a file named statefulset.yaml and copy the following code to the file:

      apiVersion: apps.kruise.io/v1alpha1
      kind: StatefulSet
      metadata:
        name: demo-asts
      spec:
        replicas: 3
        selector:
          matchLabels:
            app: guestbook-sts
        podManagementPolicy: Parallel
        template: #The schema of the pod template is the same as that of a StatefulSet YAML. 
          metadata:
            labels:
              app: guestbook-sts
          spec:
            containers:
            - name: guestbook
              image: registry.cn-hangzhou.aliyuncs.com/kruise-test/guestbook:v1
              env:
              - name: test
                value: foo
              volumeMounts:
              - name: log-volume
                mountPath: /var/log
            readinessGates:
            - conditionType: InPlaceUpdateReady
            volumes:
            - name: log-volume
              emptyDir: {}
        updateStrategy:
          type: RollingUpdate
          rollingUpdate:
            podUpdatePolicy: InPlaceIfPossible #We recommend that you perform an in-place upgrade instead of upgrading pods upon recreation. 
            maxUnavailable: 20% #A maximum of 20% pods can be unavailable during the release. 
            inPlaceUpdateStrategy:
              gracePeriodSeconds: 3 #The graceful period specifies how long a pod stays in the Not-ready state before the controller performs an in-place upgrade on the pod. 

      • type: specifies the upgrade strategy. The following three strategies are supported:
        • ReCreate: The controller deletes the current pods and PVCs, and then creates new pods and PVCs.
        • InPlaceIfPossible: The controller attempts to perform an in-place upgrade. If the attempt fails, the controller upgrades the pods by recreating them.
        • InPlaceOnly: The controller is allowed to perform only in-place upgrades.
      • maxUnavailable: The maximum number of pods that can be unavailable during the upgrade process. You can specify an absolute value or a percentage value.
      • gracePeriodSeconds: The grace period specifies how long a pod stays in the Not-ready state before the controller performs an in-place upgrade on the pod.
   2. Make the statefulset.yaml file effective in the ACK cluster.

       kubectl create -f ./statefulset.yaml

      Expected output:

      statefulset.apps.kruise.io/demo-asts created

2. Query the status of the pods:

   kubectl get pod

   Expected output:

   NAME          READY   STATUS    RESTARTS   AGE
   demo-asts-0   1/1     Running   0          3h29m
   demo-asts-1   1/1     Running   0          3h29m
   demo-asts-2   1/1     Running   0          3h29m

3. Query the Advanced StatefulSet.

   kubectl get asts

   Expected output:

   NAME        DESIRED   CURRENT   UPDATED   READY   AGE
   demo-asts   3         3         3         3       3h30m

   • DESIRED: the expected number of pods (spec.replicas).
   • UPDATED: the number of pods that are upgraded (status.updatedReplicas).
   • READY: the total number of available pods (status.readyReplicas).
   • TOTAL: the total number of pods (status.replicas).