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 type Services.

1. Create a Deployment and a Service.

   You can copy the following content into a YAML file and run the kubectl create -f nginx-service-ack.yaml command to create a Deployment and a Service.

   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 to go to the All Zones tab.
5. On the All Zones tab, find the zone that you want to manage and click Configure in the Actions column. The resolution settings page appears.
   Note Each record is in the $svc.$ns format and corresponds to an IP address. The following resolution rules apply:

   • A LoadBalancer type Service corresponds to only one resolution record in Alibaba Cloud DNS PrivateZone. The record corresponds to the IP address of the related Server Load Balancer (SLB) instance.
   • A ClusterIP type Service corresponds to only one resolution record in Alibaba Cloud DNS PrivateZone. The record corresponds to the IP address of the cluster.
   • A headless Service corresponds to multiple resolution records in Alibaba Cloud DNS PrivateZone. These records correspond to the IP addresses of the backend pods.

   You can access a Service by using the private domain name in the VPC.

   • Long domain name: You can use a long domain name of the $svc.$ns.svc.cluster.local.$clusterId format to access Services that are synchronized from other clusters to Alibaba Cloud DNS PrivateZone.
   • Short domain name: You can use a short domain name of the $svc format to access Services in the same namespace. You can use a short domain name of the $svc.$ns format to access Services in other namespaces.

   For more information, see serverless-k8s-examples.