Use the service discovery feature based on Alibaba Cloud DNS PrivateZone in ASK clusters

Serverless Kubernetes (ASK) clusters support service discovery for intranet Services, headless Services, and ClusterIP Services.

1. Create a Deployment and Services.

   You can add the following sample code to a YAML file and run the kubectl create -f nginx-service-ack.yaml command to create a Deployment and Services.

   apiVersion: v1
   kind: Service
   metadata:
     name: nginx-headless-service
   spec:
     ports:
     - port: 80
       protocol: TCP
     selector:
       app: nginx
     clusterIP: None
   ---
   apiVersion: v1
   kind: Service
   metadata:
     name: nginx-clusterip-service
   spec:
     ports:
     - port: 80
       protocol: TCP
     selector:
       app: nginx
     type: ClusterIP
   ---
   apiVersion: v1
   kind: Service
   metadata:
     name: nginx-intranet-service
     annotations:
       service.beta.kubernetes.io/alicloud-loadbalancer-address-type: intranet
   spec:
     ports:
     - port: 80
       protocol: TCP
     selector:
       app: nginx
     type: LoadBalancer
   ---
   apiVersion: apps/v1
   kind: Deployment
   metadata:
     name: nginx-deployment
     labels:
       app: nginx
   spec:
     replicas: 3
     selector:
       matchLabels:
         app: nginx
     template:
       metadata:
         labels:
           app: nginx
       spec:
         containers:
         - name: nginx
           image:  nginx:alpine
           ports:
           - containerPort: 80

2. Run the following command to view the state of the created application:

   kubectl get svc,pod,deployment

3. Log on to the Alibaba Cloud DNS console.
4. In the left-side navigation pane, click PrivateZone. On the page that appears, click the Hosted Zones tab.
5. Select the zone that you want to manage and click Configure in the Actions column.
   Note All PrivateZone records are in the $svc.$ns format. Each PrivateZone record maps a Service to an IP address. The following resolution rules apply:

   • A LoadBalancer Service corresponds to only one PrivateZone record. The record maps the Service to the IP address of the Server Load Balancer (SLB) instance.
   • A ClusterIP Service corresponds to only one PrivateZone record. The record maps the Service to the IP address of the cluster.
   • A headless Service corresponds to multiple PrivateZone records. The records map the Service to the IP addresses of backend pods.

   You can access a Service within the VPC through the private domain name of the Service.

   • You can use $svc.$ns.svc.cluster.local.$clusterId to access Services that are discovered in the current cluster. You can also use the long domain name to access Services in other clusters after you use Alibaba Cloud DNS PrivateZone to discover these Services.
   • You can use $svc to access Services in the current namespace and use $svc.$ns to access Services in other namespaces.

   For more information, see serverless-k8s-examples.