Container Service for Kubernetes:Use an existing Server Load Balancer instance to expose an application

Use the console

1. Log on to the ACK console. In the left navigation pane, click Clusters.

2. On the Clusters page, find the cluster you want to manage and click its name. In the left navigation pane, choose Workloads > Deployments.

3. On the Deployments page, click Create from Image, and configure the basic information, container, and advanced settings for the application.

   1. On the Basic Information tab, set Application Name to my-nginx, retain the default values for the other parameters, and then click Next.

   2. On the Container Configuration tab, set the container image name and port, retain the default values for the other parameters, and then click Next.

      Configuration item	Value
      Image Name	Click Select Image. In the Select Image and Version dialog box, click the Artifact Center tab, search for nginx, select the image repository named openanolis/nginx, click Select Image Version, set the image version, and then click OK.
      Port	Name: nginx. Container Port: 80.

   3. On the Advanced Configuration tab, retain the default settings and click Create to create the Nginx application.

Use kubectl

1. Create a file named my-nginx.yaml that contains the following YAML content for the sample application.

   apiVersion: apps/v1 # for versions before 1.8.0 use apps/v1beta1
   kind: Deployment
   metadata:
     name: my-nginx    # The name of the sample application.
     labels:
       app: nginx
   spec:
     replicas: 2       # The number of replicas.
     selector:
       matchLabels:
         app: nginx     # The value of Selector in the corresponding Service must be the same to expose this application through the Service.
     template:
       metadata:
         labels:
           app: nginx
       spec:
       #  nodeSelector:
       #    env: test-team
         containers:
         - name: nginx
           image: anolis-registry.cn-zhangjiakou.cr.aliyuncs.com/openanolis/nginx:1.14.1-8.6
           ports:
           - containerPort: 80                                # This port needs to be exposed in the Service.

2. Run the following command to deploy the my-nginx sample application.

   kubectl apply -f my-nginx.yaml

3. You can run the following command to confirm that the sample application is in the Normal state.

   kubectl get deployment my-nginx

   Expected output:

   NAME       READY   UP-TO-DATE   AVAILABLE   AGE
   my-nginx   2/2     2            2           50s

Use the console

1. Log on to the ACK console. In the left navigation pane, click Clusters.

2. On the Clusters page, find the cluster you want and click its name. In the left-side pane, choose Network > Services.

3. On the Services page, click Create. In the Create Service dialog box that appears, set the parameters for the Service.

   Configuration item	Description	Example
   Service Name	The name of the Service.	my-nginx-svc
   Service Type	Select a Service type. The Service network supports the following modes to handle access from clients of different sources and types: ClusterIP A ClusterIP Service is used for communication within the cluster. Service discovery is supported only when the service type is set to ClusterIP. You can use a Headless Service to interact with other service discovery mechanisms without having to rely on the default ClusterIP-based service discovery and load balancing provided by Kubernetes. LoadBalancer A LoadBalancer Service exposes applications to the internet by integrating with Alibaba Cloud Classic Load Balancer (CLB) and Network Load Balancer (NLB). Compared with a NodePort Service, a LoadBalancer Service significantly improves application availability and performance. The following types are supported: CLB: For configuration information, see Classic Load Balancer (CLB). NLB: For configuration information, see Network Load Balancer (NLB). NodePort A NodePort Service provides a convenient way for external users to access services in a cluster through the IP address and a specified port of a node. Users can connect to a NodePort Service by accessing <NodeIP>:<NodePort>. However, you must manually configure load balancing.	Select LoadBalancer as the service type. Set Load Balancer Type to Classic Load Balancer (CLB) and select Use Existing Resource. If Cloud Controller Manager (CCM) is v2.5.0 or later, the CLB option is a whitelisted feature. To use this feature, submit a request in Quota Center. Then, select the created CLB instance from the drop-down list. In this example, the CLB instance is newly created and requires a listener. Therefore, select Force Overwrite Existing Listeners.
   External Traffic Policy	The External Traffic Policy parameter is available only if you set the Service Type parameter to Node Port or Server Load Balancer. For more information about external traffic policies, see the Differences between external traffic policies section of the "Getting started" topic. Valid values: Local: routs traffic only to the pods of the current node. Cluster: routes traffic to pods on other nodes in the cluster.	Local
   Service Association	The backend application that you want to associate with the Service. If you do not select a backend application, no Endpoint objects are created. For more information, see Services-without-selectors.	Name: app Value: nginx
   Port Mapping	The Service port and container port. The Service port corresponds to the port field in the YAML file and the container port corresponds to the targetPort field in the YAML file. The container port must be the same as the port that is exposed in the backend pod.	Service Port: 80 Container Port: 80 Protocol: TCP
   Annotations	The annotations to be added to the Service to configure the SLB instance. For more information, see Use annotations to configure CLB instances and Configure an NLB instance using annotations. Important Do not reuse the SLB instance of the cluster's API Server. Otherwise, cluster access becomes abnormal.	None

   After you configure the parameters, click OK.

4. After the Service is created, click its name to go to the details page. In the Basic Information section, click the External IP address of the Service, such as 39.106.XX.XX:80, to access the sample application.

   

Use kubectl

1. Create a Service.

   Create a file named my-nginx-svc.yaml that contains the following YAML content for the sample Service.

   • Modify the service.beta.kubernetes.io/alibaba-cloud-loadbalancer-id annotation. Replace ${YOUR_LB_ID} with the ID of the SLB instance that you created in the SLB console.

   • When you use an existing SLB instance, a listener is not created for the SLB instance and existing listeners are not overwritten by default. To overwrite the listeners, you can set the service.beta.kubernetes.io/alibaba-cloud-loadbalancer-force-override-listeners annotation to "true". In this example, the SLB instance is newly created and requires a listener. Therefore, the value is set to true. For more information about annotations, see Use annotations to configure Classic Load Balancer (CLB) instances and Use annotations to configure Network Load Balancer (NLB) instances.

   • Change the value of selector to the value of matchLabels in the my-nginx.yaml file of the sample application. The value is app: nginx. This associates the Service with the backend application.

   apiVersion: v1
   kind: Service # Defines the resource object as a Service.
   metadata:
     annotations:
       service.beta.kubernetes.io/alibaba-cloud-loadbalancer-id: ${YOUR_LB_ID}
       service.beta.kubernetes.io/alibaba-cloud-loadbalancer-force-override-listeners: 'true'
     labels:
       app: nginx
     name: my-nginx-svc
     namespace: default
   spec:
     ports:
     - port: 80
       protocol: TCP
       targetPort: 80
     selector:
       app: nginx
     type: LoadBalancer

   Field	Description
   kind	Defines the resource object as a Service.
   metadata	Defines the basic information about the Service, such as the name, label, and namespace.
   metadata.annotations	A rich set of SLB-related annotations are supported. For example, in the preceding YAML sample, service.beta.kubernetes.io/alibaba-cloud-loadbalancer-id specifies an existing CLB instance. For more information about annotations, see Use annotations to configure Classic Load Balancer (CLB) instances.
   spec.selector	Defines the selector for the Service. The Service determines the backend pods to associate and expose based on the matching relationship between the selector and pod labels.
   spec.ports.port	Defines the port exposed by the Service to the ClusterIP. This is the entry point for clients within the cluster to access the Service, which is clusterIP:port.
   spec.ports.targetPort	Defines the port of the backend pod. Traffic coming in through the port flows through kube-proxy to the targetPort of the backend pod and finally enters the container.

2. Run the following command to create a Service named my-nginx-svc and use it to expose the application.

   kubectl apply -f my-nginx-svc.yaml

3. Run the following command to confirm that the LoadBalancer Service is created.

   kubectl get svc my-nginx-svc

   Expected output:

   NAME           TYPE           CLUSTER-IP    EXTERNAL-IP      PORT(S)        AGE
   my-nginx-svc   LoadBalancer   172.21.5.82   39.106.XX.XX     80:30471/TCP   5m

4. Run the following command to access the sample application.

   curl <YOUR-External-IP> # Replace <YOUR-External-IP> with the EXTERNAL-IP address obtained above.

   Expected output:

   <!DOCTYPE html>
   <html>
   <head>
   <title>Welcome to nginx!</title>
   <style>
       body {
           width: 35em;
           margin: 0 auto;
           font-family: Tahoma, Verdana, Arial, sans-serif;
       }
   </style>
   </head>
   <body>
   <h1>Welcome to nginx!</h1>
   <p>If you see this page, the nginx web server is successfully installed and
   working. Further configuration is required.</p>
   
   <p>For online documentation and support please refer to
   <a href="http://nginx.org/">nginx.org</a>.<br/>
   Commercial support is available at
   <a href="http://nginx.com/">nginx.com</a>.</p>
   
   <p>Thank you for using nginx.

Use the console

1. Log on to the ACK console. In the left navigation pane, click Clusters.

2. On the Clusters page, find the cluster you want and click its name. In the left-side pane, choose Network > Services.

3. On the Services page, click Update or Delete in the Actions column of the target Service to update or delete the Service.

Use kubectl

kubectl get service my-nginx-svc

NAME           TYPE           CLUSTER-IP    EXTERNAL-IP      PORT(S)        AGE
my-nginx-svc   LoadBalancer   172.21.XX.XX   192.168.XX.XX     80:31599/TCP   5m

kubectl delete service my-nginx-svc