Container Service for Kubernetes:Use a Fleet instance as a proxy to manage multiple clusters

Run the following command to query the clusters that are associated with the Fleet instance:

kubectl get managedclusters

NAME                     HUB ACCEPTED   MANAGED CLUSTER URLS   JOINED   AVAILABLE   AGE
managedcluster-c5***z9   true                                  True     True        12d
managedcluster-c1***e5   true                                  True     True        12d

Create a file named app.yaml with the following content:

apiVersion: apps/v1
kind: Deployment
metadata:
  name: demo
  namespace: demo
  labels:
    app: demo
spec:
  minReadySeconds: 5
  revisionHistoryLimit: 5
  progressDeadlineSeconds: 60
  strategy:
    rollingUpdate:
      maxUnavailable: 1
    type: RollingUpdate
  selector:
    matchLabels:
      app: demo
  template:
    metadata:
      annotations:
        prometheus.io/scrape: "true"
        prometheus.io/port: "9797"
      labels:
        app: demo
    spec:
      containers:
      - name: demo
        image: registry.cn-hangzhou.aliyuncs.com/acs/rollouts-demo:red
        imagePullPolicy: IfNotPresent
        ports:
        - name: http
          containerPort: 8080
          protocol: TCP
        readinessProbe:
          tcpSocket:
            port: 8080
          initialDelaySeconds: 5
          timeoutSeconds: 5
        resources:
          limits:
            cpu: 2000m
            memory: 512Mi
          requests:
            cpu: 100m
            memory: 64Mi
---
apiVersion: v1
kind: Service
metadata:
  name: demo-svc
  namespace: demo
spec:
  selector:
    app: demo
  ports:
    - protocol: TCP
      port: 80
      targetPort: 8080
---
apiVersion: networking.k8s.io/v1
kind: Ingress
metadata:
  name: demo
  namespace: demo
  labels:
    app: demo
spec:
  rules:
    - host: app.demo.example.com
      http:
        paths:
        - path: /
          pathType: Prefix
          backend:
            service:
              name: demo-svc
              port:
                number: 80

Run the following command to deploy an application named demo on the Fleet instance.

kubectl amc apply -f app.yaml -m managedcluster-c1***e5

Run on ManagedCluster managedcluster-c1***e5
deployment.apps/demo created
service/demo-svc created
ingress.networking.k8s.io/demo created

Query the status of the application.

• Run the following command to query the status of the Deployment:

  kubectl amc get deployment -n demo -m managedcluster-c1***e5

  Expected output:

  Run on ManagedCluster managedcluster-c1xxxe5
  NAME   READY   UP-TO-DATE   AVAILABLE   AGE
  demo   1/1     1            1           2m48s

• Run the following command to query the status of the pod:

  kubectl amc get pod -n demo -m managedcluster-c1***e5

  Expected output:

  Run on ManagedCluster managedcluster-c1***e5
  NAME                   READY   STATUS    RESTARTS   AGE
  demo-fdf4b6b7d-vthqj   1/1     Running   0          6m55s

• Run the following command to print the log of the pod:

  kubectl amc logs demo-fdf4b6b7d-vthqj -n demo -m managedcluster-c1***e5

  Expected output:

  Run on ManagedCluster managedcluster-c1***e5
  2021-12-16 24:00:00 Started server on :8080

• Run the following command to query the status of the Service:

  kubectl amc get service -n demo -m managedcluster-c1***e5

  Expected output:

  Run on ManagedCluster managedcluster-c1***e5
  NAME       TYPE        CLUSTER-IP     EXTERNAL-IP   PORT(S)   AGE
  demo-svc   ClusterIP   172.16.17.29   <none>        80/TCP    3m55s

• Run the following command to query the status of the Ingress:

  kubectl amc get ingress -n demo -m managedcluster-c1***e5

  Expected output:

  Run on ManagedCluster managedcluster-c1***e5
  NAME   CLASS    HOSTS                  ADDRESS        PORTS   AG
  demo   <none>   app.demo.example.com   123.56.XX.XX   80      4m10s

Call the Kubernetes API to query the clusters that are associated with your Fleet instance.

1. Run the following commands to view the KubeConfig of the Fleet instance, obtain the values of the ca, key, and apiserver fields in the KubeConfig, and specify the authentication information that is required when you call the Kubernetes API:

   cat  $KUBECONFIG |grep client-certificate-data | awk -F ' ' '{print $2}' |base64 -d > client-cert.pem
   cat  $KUBECONFIG |grep client-key-data | awk -F ' ' '{print $2}' |base64 -d > client-key.pem
   APISERVER=`cat  $KUBECONFIG |grep server | awk -F ' ' '{print $2}'`

2. Call the Kubernetes API of the Fleet instance to query the clusters that are associated with the Fleet instance.

   curl --cert client-cert.pem --key client-key.pem -k $APISERVER/apis/cluster.open-cluster-management.io/v1/managedclusters

   Note

   The URL of the Kubernetes API is /apis/cluster.open-cluster-management.io/v1/managedclusters.

Use the proxy feature provided by the Kubernetes API of the Fleet instance to query resources in a cluster that is associated with the Fleet instance.

curl --cert client-cert.pem --key client-key.pem -k $APISERVER/apis/cluster.core.oam.dev/v1alpha1/clustergateways/<The name of the cluster that you want to query>/proxy/api/v1/namespaces/demo/pods