YurtAppSet

In the previous article we introduced the use of NodePool, mainly the creation and management of NodePool. Further, we developed the ability to deploy applications unitized based on NodePool to improve the efficiency of users' operations.

In this article, we will show how yurt-app-manager can help users manage their workload. Assume we already have an OpenYurt cluster built on native kubernetes with at least two nodes.

1) Create YurtAppSet

• Create YurtAppSet by yurtappset_test.yaml

apiVersion: apps.openyurt.io/v1alpha1
kind: YurtAppSet
metadata:
  labels:
    controller-tools.k8s.io: "1.0"
  name: yas-test
spec:
  selector:
    matchLabels:
      app: yas-test
  workloadTemplate:
    deploymentTemplate:
      metadata:
        labels:
          app: yas-test
      spec:
        template:
          metadata:
            labels:
              app: yas-test
          spec:
            containers:
              - name: nginx
                image: nginx:1.19.3
  topology:
    pools:
    - name: beijing 
      nodeSelectorTerm:
        matchExpressions:
        - key: apps.openyurt.io/nodepool
          operator: In
          values:
          - beijing 
      replicas: 1
    - name: hangzhou 
      nodeSelectorTerm:
        matchExpressions:
        - key: apps.openyurt.io/nodepool
          operator: In
          values:
          - hangzhou 
      replicas: 2
      tolerations:
      - effect: NoSchedule
        key: apps.openyurt.io/example
        operator: Exists
  revisionHistoryLimit: 5 

• Check YurtAppSet

$ kubectl get yas
NAME       READY   WORKLOADTEMPLATE   AGE
yas-test   3       Deployment         43s

2) Check the deployments created by yurt-app-manager

$ kubectl get deploy
NAME                      READY   UP-TO-DATE   AVAILABLE   AGE
yas-test-beijing-k5st4    1/1     1            1           54s
yas-test-hangzhou-2jkj5   2/2     2            2           54s

$ kubectl get pod -l app=yas-test
NAME                                       READY   STATUS    RESTARTS   AGE
yas-test-beijing-k5st4-56bc98cc7d-h7h86    1/1     Running   0          72s
yas-test-hangzhou-2jkj5-64588c484b-8mvn8   1/1     Running   0          72s
yas-test-hangzhou-2jkj5-64588c484b-vx85t   1/1     Running   0          72s

3) Add patch to YurtAppSet

• Add the patch field to the file yurtappset_test.yaml as follows, lines 36 to 41 of the file

$ kubectl get yas yas-test -o yaml
   
  topology:
    pools:
    - name: beijing 
      nodeSelectorTerm:
        matchExpressions:
        - key: apps.openyurt.io/nodepool
          operator: In
          values:
          - beijing 
      replicas: 1
      patch:
        spec:
          template:
            spec:
              containers:
                - name: nginx
                  image: nginx:1.19.0
    - name: hangzhou 
      nodeSelectorTerm:
        matchExpressions:
        - key: apps.openyurt.io/nodepool
          operator: In
          values:
          - hangzhou 
      replicas: 2
      tolerations:
  *** 

• This updates the nginx image version to 1.19.0 in the deployments and pods in Beijing NodePool, while keeping the nginx image version at 1.19.3 for the other regions

$ kubectl get deploy yas-test-beijing-k5st4 -o yaml
containers:
  - image: nginx:1.19.0

$ kubectl get deploy yas-test-hangzhou-2jkj5 -o yaml
containers:
  - image: nginx:1.19.3

• After removing the patch, all pods created by YurtAppSet revert back to nginx1.19.3

$ kubectl get pod yas-test-beijing-k5st4-974b6958c-t2kfn -o yaml
containers:
  - image: nginx:1.19.3

$ kubectl get pod yas-test-hangzhou-2jkj5-64588c484b-8mvn8 -o yaml
containers:
  - image: nginx:1.19.3

• Conclusion: Patch solves the upgrade of the NodePool's single attribute and application release.