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Install Guestbook Application

This tutorial walks you through an example to install a guestbook application using advanced statefulset. The guestbook app used is from this repo.

Installing the Guestbook application using Helm

To install the chart with release name (application name) of demo-v1, replica of 20:

helm install demo-v1 apphub/guestbook-kruise --set replicaCount=20,image.repository=openkruise/guestbook

The Chart is located in this repo.

Now the guestbook-kruise app has been installed!

If you don't use helm, you need to install with YAML files as below.

Install the Guestbook application with YAML files

Below installs a redis cluster with 1 master 2 replicas

kubectl apply -f https://raw.githubusercontent.com/kruiseio/kruise/master/docs/tutorial/v1/redis-master-deployment.yaml
kubectl apply -f https://raw.githubusercontent.com/kruiseio/kruise/master/docs/tutorial/v1/redis-master-service.yaml
kubectl apply -f https://raw.githubusercontent.com/kruiseio/kruise/master/docs/tutorial/v1/redis-slave-deployment.yaml
kubectl apply -f https://raw.githubusercontent.com/kruiseio/kruise/master/docs/tutorial/v1/redis-slave-service.yaml

Below creates a guestbook application using advanced statefulset.

kubectl apply -f https://raw.githubusercontent.com/kruiseio/kruise/master/docs/tutorial/v1/guestbook-statefulset.yaml
kubectl apply -f https://raw.githubusercontent.com/kruiseio/kruise/master/docs/tutorial/v1/guestbook-service.yaml

Several things to note in the guestbook-statefulset.yaml

* apiVersion: apps.kruise.io/v1alpha1  # the kruise group version
  kind: StatefulSet
  ...
    spec:
*     readinessGates:
*        # A new condition must be added to ensure the pod remain at NotReady state while the in-place update is happening
*        - conditionType: InPlaceUpdateReady
      containers:
      - name: guestbook-kruise
        image: openkruise/guestbook:v1
        ports:
        - name: http-server
          containerPort: 3000
*    podManagementPolicy: Parallel  # allow parallel updates, works together with maxUnavailable
*    updateStrategy:
*       type: RollingUpdate
*       rollingUpdate:
*         # Do in-place update if possible, currently only image update is supported for in-place update
*         podUpdatePolicy: InPlaceIfPossible
*         # Allow parallel updates with max number of unavailable instances equals to 3
*         maxUnavailable: 3

Now the app has been installed.

Verify Guestbook Started

Check the guestbook are started. statefulset.apps.kruise.io or shortname sts.apps.kruise.io is the resource kind. app.kruise.io postfix needs to be appended due to naming collision with Kubernetes native statefulset kind. Verify that all pods are READY.

kubectl get sts.apps.kruise.io

NAME           DESIRED   CURRENT   UPDATED   READY   AGE
demo-v1-guestbook-kruise   20        20        20        20      6m

View the Guestbook

You can now view the Guestbook on browser.

  • Local Host: If you are running Kubernetes locally, to view the guestbook, navigate to http://localhost:3000 for the guestbook

  • Remote Host: To view the guestbook on a remote host, locate the external IP of the application in the IP column of the kubectl get services output. For example, run

kubectl get svc

NAME           TYPE           CLUSTER-IP     EXTERNAL-IP     PORT(S)                         AGE
guestbook      LoadBalancer   172.21.2.187   47.101.74.131   3000:31459/TCP,4000:32099/TCP   35m

47.101.74.131 is the external IP. Visit http://47.101.74.131:3000 for the guestbook UI. Guestbook

Inplace-update guestbook to the new image

First, check the running pods.

kubectl get pod -L controller-revision-hash -o wide | grep guestbook
NAME                                        READY   STATUS    RESTARTS   AGE     IP             NODE            NOMINATED NODE   CONTROLLER-REVISION-HASH
demo-v1-guestbook-kruise-0                  1/1     Running   0          35s     172.29.1.21    192.168.1.113   <none>           demo-v1-guestbook-kruise-7c947b5f94
demo-v1-guestbook-kruise-1                  1/1     Running   0          35s     172.29.0.148   192.168.1.112   <none>           demo-v1-guestbook-kruise-7c947b5f94
demo-v1-guestbook-kruise-10                 1/1     Running   0          33s     172.29.1.23    192.168.1.113   <none>           demo-v1-guestbook-kruise-7c947b5f94
demo-v1-guestbook-kruise-11                 1/1     Running   0          33s     172.29.0.151   192.168.1.112   <none>           demo-v1-guestbook-kruise-7c947b5f94
demo-v1-guestbook-kruise-12                 1/1     Running   0          32s     172.29.0.152   192.168.1.112   <none>           demo-v1-guestbook-kruise-7c947b5f94
demo-v1-guestbook-kruise-13                 1/1     Running   0          32s     172.29.0.153   192.168.1.112   <none>           demo-v1-guestbook-kruise-7c947b5f94
demo-v1-guestbook-kruise-14                 1/1     Running   0          32s     172.29.0.27    192.168.1.114   <none>           demo-v1-guestbook-kruise-7c947b5f94
demo-v1-guestbook-kruise-15                 1/1     Running   0          31s     172.29.0.28    192.168.1.114   <none>           demo-v1-guestbook-kruise-7c947b5f94
demo-v1-guestbook-kruise-16                 1/1     Running   0          31s     172.29.1.24    192.168.1.113   <none>           demo-v1-guestbook-kruise-7c947b5f94
demo-v1-guestbook-kruise-17                 1/1     Running   0          30s     172.29.0.29    192.168.1.114   <none>           demo-v1-guestbook-kruise-7c947b5f94
demo-v1-guestbook-kruise-18                 1/1     Running   0          30s     172.29.0.154   192.168.1.112   <none>           demo-v1-guestbook-kruise-7c947b5f94
demo-v1-guestbook-kruise-19                 1/1     Running   0          30s     172.29.1.25    192.168.1.113   <none>           demo-v1-guestbook-kruise-7c947b5f94
demo-v1-guestbook-kruise-2                  1/1     Running   0          35s     172.29.0.22    192.168.1.114   <none>           demo-v1-guestbook-kruise-7c947b5f94
demo-v1-guestbook-kruise-3                  1/1     Running   0          35s     172.29.0.149   192.168.1.112   <none>           demo-v1-guestbook-kruise-7c947b5f94
demo-v1-guestbook-kruise-4                  1/1     Running   0          35s     172.29.0.23    192.168.1.114   <none>           demo-v1-guestbook-kruise-7c947b5f94
demo-v1-guestbook-kruise-5                  1/1     Running   0          35s     172.29.1.22    192.168.1.113   <none>           demo-v1-guestbook-kruise-7c947b5f94
demo-v1-guestbook-kruise-6                  1/1     Running   0          35s     172.29.0.24    192.168.1.114   <none>           demo-v1-guestbook-kruise-7c947b5f94
demo-v1-guestbook-kruise-7                  1/1     Running   0          34s     172.29.0.150   192.168.1.112   <none>           demo-v1-guestbook-kruise-7c947b5f94
demo-v1-guestbook-kruise-8                  1/1     Running   0          34s     172.29.0.25    192.168.1.114   <none>           demo-v1-guestbook-kruise-7c947b5f94
demo-v1-guestbook-kruise-9                  1/1     Running   0          34s     172.29.0.26    192.168.1.114   <none>           demo-v1-guestbook-kruise-7c947b5f94

Run this command to update the statefulset to use the new image.

kubectl apply -f https://raw.githubusercontent.com/kruiseio/kruise/master/docs/tutorial/v1/guestbook-patch-to-v2.yaml

What this command does is that it changes the image version to v2 and changes partition to 15. This will update pods with ordinal number >= 15 (i.e. 15 - 19)to image version v2. The rest pods (0 ~ 14) will remain at version v1. The YAML diff details are shown below:

spec:
    ...
      containers:
      - name: guestbook-kruise
-       image: openkruise/guestbook:v1
+       image: openkruise/guestbook:v2
  podManagementPolicy: Parallel  # allow parallel updates, works together with maxUnavailable
  updateStrategy:
    type: RollingUpdate
    rollingUpdate:
      # Do in-place update if possible, currently only image update is supported for in-place update
      podUpdatePolicy: InPlaceIfPossible
      # Allow parallel updates with max number of unavailable instances equals to 2
      maxUnavailable: 3
+     partition: 15

Check the statefulset, find the statefulset has 5 pods updated

kubectl get sts.apps.kruise.io

NAME                       DESIRED   CURRENT   UPDATED   READY   AGE
demo-v1-guestbook-kruise   20        20        5         20      18h

Check the pods again. demo-v1-guestbook-kruise-15 to demo-v1-guestbook-kruise-19 are updated with RESTARTS showing 1, IPs remain the same, CONTROLLER-REVISION-HASH are updated from demo-v1-guestbook-kruise-7c947b5f94 to demo-v1-guestbook-kruise-576bd76785

kubectl get pod -L controller-revision-hash -o wide | grep guestbook

NAME                                        READY   STATUS    RESTARTS   AGE     IP             NODE            NOMINATED NODE   CONTROLLER-REVISION-HASH
demo-v1-guestbook-kruise-0                  1/1     Running   0          3m22s   172.29.1.21    192.168.1.113   <none>           demo-v1-guestbook-kruise-7c947b5f94
demo-v1-guestbook-kruise-1                  1/1     Running   0          3m22s   172.29.0.148   192.168.1.112   <none>           demo-v1-guestbook-kruise-7c947b5f94
demo-v1-guestbook-kruise-10                 1/1     Running   0          3m20s   172.29.1.23    192.168.1.113   <none>           demo-v1-guestbook-kruise-7c947b5f94
demo-v1-guestbook-kruise-11                 1/1     Running   0          3m20s   172.29.0.151   192.168.1.112   <none>           demo-v1-guestbook-kruise-7c947b5f94
demo-v1-guestbook-kruise-12                 1/1     Running   0          3m19s   172.29.0.152   192.168.1.112   <none>           demo-v1-guestbook-kruise-7c947b5f94
demo-v1-guestbook-kruise-13                 1/1     Running   0          3m19s   172.29.0.153   192.168.1.112   <none>           demo-v1-guestbook-kruise-7c947b5f94
demo-v1-guestbook-kruise-14                 1/1     Running   0          3m19s   172.29.0.27    192.168.1.114   <none>           demo-v1-guestbook-kruise-7c947b5f94
demo-v1-guestbook-kruise-15                 1/1     Running   1          3m18s   172.29.0.28    192.168.1.114   <none>           demo-v1-guestbook-kruise-576bd76785
demo-v1-guestbook-kruise-16                 1/1     Running   1          3m18s   172.29.1.24    192.168.1.113   <none>           demo-v1-guestbook-kruise-576bd76785
demo-v1-guestbook-kruise-17                 1/1     Running   1          3m17s   172.29.0.29    192.168.1.114   <none>           demo-v1-guestbook-kruise-576bd76785
demo-v1-guestbook-kruise-18                 1/1     Running   1          3m17s   172.29.0.154   192.168.1.112   <none>           demo-v1-guestbook-kruise-576bd76785
demo-v1-guestbook-kruise-19                 1/1     Running   1          3m17s   172.29.1.25    192.168.1.113   <none>           demo-v1-guestbook-kruise-576bd76785
demo-v1-guestbook-kruise-2                  1/1     Running   0          3m22s   172.29.0.22    192.168.1.114   <none>           demo-v1-guestbook-kruise-7c947b5f94
demo-v1-guestbook-kruise-3                  1/1     Running   0          3m22s   172.29.0.149   192.168.1.112   <none>           demo-v1-guestbook-kruise-7c947b5f94
demo-v1-guestbook-kruise-4                  1/1     Running   0          3m22s   172.29.0.23    192.168.1.114   <none>           demo-v1-guestbook-kruise-7c947b5f94
demo-v1-guestbook-kruise-5                  1/1     Running   0          3m22s   172.29.1.22    192.168.1.113   <none>           demo-v1-guestbook-kruise-7c947b5f94
demo-v1-guestbook-kruise-6                  1/1     Running   0          3m22s   172.29.0.24    192.168.1.114   <none>           demo-v1-guestbook-kruise-7c947b5f94
demo-v1-guestbook-kruise-7                  1/1     Running   0          3m21s   172.29.0.150   192.168.1.112   <none>           demo-v1-guestbook-kruise-7c947b5f94
demo-v1-guestbook-kruise-8                  1/1     Running   0          3m21s   172.29.0.25    192.168.1.114   <none>           demo-v1-guestbook-kruise-7c947b5f94
demo-v1-guestbook-kruise-9                  1/1     Running   0          3m21s   172.29.0.26    192.168.1.114   <none>           demo-v1-guestbook-kruise-7c947b5f94

Now upgrade all the pods, run

kubectl edit sts.apps.kruise.io demo-v1-guestbook-kruise

and update partition to 0, all pods will be updated to v2 this time, and all pods' IP remain unchanged. You should also find that all 20 pods are updated fairly fast because the maxUnavailable feature allows parallel updates instead of sequential update.

kubectl get sts.apps.kruise.io
NAME           DESIRED   CURRENT   UPDATED   READY   AGE
demo-v1-guestbook-kruise   20        20        20        20      18h

Describe a pod and find that the events show the original container is killed and new container is started. This verifies in-place update

kubectl describe pod demo-v1-guestbook-kruise-0

...
Events:
  Type    Reason   Age                From                                Message
  ----    ------   ----               ----                                -------
  Normal  Created  10m (x2 over 18h)  kubelet, 192.168.1.107  Created container
  Normal  Started  10m (x2 over 18h)  kubelet, 192.168.1.107  Started container
  Normal  Killing  10m                kubelet, 192.168.1.107  Killing container with id docker://guestbook:Container spec hash changed (4055768332 vs 2933593838).. Container will be killed and recreated.
  Normal  Pulled   10m                kubelet, 192.168.1.107  Container image "openkruise/guestbook:v3" already present on machine

The pods should also be in Ready state, the InPlaceUpdateReady will be set to False right before in-place update and to True after update is complete

Readiness Gates:
  Type                 Status
  InPlaceUpdateReady   True
Conditions:
  Type                 Status
  InPlaceUpdateReady   True  # Should be False right before in-place update and True after update is complete
  Initialized          True
  Ready                True  # Should be True after in-place update is complete
  ContainersReady      True
  PodScheduled         True

Uninstall app

Using helm to uninstall apps is very easy.

First you may want to list your helm apps:

helm list
NAME          NAMESPACE  REVISION  UPDATED                               STATUS    CHART
demo-v1       default    1         2019-06-23 13:33:21.278013 +0800 CST  deployed  guestbook-kruise-0.3.0

Then uninstall it:

helm uninstall demo-v1

If you are not using helm, deleting the application using below commands:

kubectl delete sts.apps.kruise.io demo-v1-guestbook-kruise
kubectl delete svc guestbook redis-master redis-slave
kubectl delete deploy redis-master redis-slave