NodePort

Scenario

Figure 1 NodePort access

Notes and Constraints

• By default, a NodePort Service is accessed within a VPC. To use an EIP to access a NodePort Service through public networks, bind an EIP to the node in the cluster in advance.
• After a Service is created, if the affinity setting is switched from the cluster level to the node level, the connection tracing table will not be cleared. Do not modify the Service affinity setting after the Service is created. To modify it, create a Service again.
• In a CCE Turbo cluster, node-level affinity is supported only when the Service backend is connected to a hostNetwork pod.
• In VPC network mode, when container A is published through a NodePort service and the service affinity is set to the node level (that is, externalTrafficPolicy is set to local), container B deployed on the same node cannot access container A through the node IP address and NodePort service.
• When a NodePort service is created in a cluster of v1.21.7 or later, the port on the node is not displayed using netstat by default. If the cluster forwarding mode is iptables, run the iptables -t nat -L command to view the port. If the cluster forwarding mode is IPVS, run the ipvsadm -Ln command to view the port.

Creating a NodePort Service

1. Log in to the CCE console and click the cluster name to access the cluster console.
2. In the navigation pane, choose Services & Ingresses. In the upper right corner, click Create Service.
3. Configure intra-cluster access parameters.
   • Service Name: Specify a Service name, which can be the same as the workload name.
   • Service Type: Select NodePort.
   • Namespace: namespace that the workload belongs to.
   • Service Affinity: For details, see externalTrafficPolicy (Service Affinity).
     • Cluster level: The IP addresses and access ports of all nodes in a cluster can access the workload associated with the Service. Service access will cause performance loss due to route redirection, and the source IP address of the client cannot be obtained.
     • Node level: Only the IP address and access port of the node where the workload is located can access the workload associated with the Service. Service access will not cause performance loss due to route redirection, and the source IP address of the client can be obtained.
   • Selector: Add a label and click Confirm. The Service will use this label to select pods. You can also click Reference Workload Label to use the label of an existing workload. In the dialog box that is displayed, select a workload and click OK.
   • IPv6: This function is disabled by default. After this function is enabled, the cluster IP address of the Service changes to an IPv6 address. This parameter is available only in clusters of v1.15 or later with IPv6 enabled (set during cluster creation).
   • Ports
     • Protocol: protocol used by the Service.
     • Service Port: port used by the Service. The port number ranges from 1 to 65535.
     • Container Port: listener port of the workload. For example, Nginx uses port 80 by default.
     • Node Port: You are advised to select Auto. You can also specify a port. The default port ranges from 30000 to 32767.

4. Click OK.

Using kubectl

1. Use kubectl to access the cluster. For details, see Accessing a Cluster Using kubectl.
2. Create and edit the nginx-deployment.yaml file to configure the sample workload. For details, see Creating a Deployment. nginx-deployment.yaml is an example file name. You can rename it as needed.

   vi nginx-deployment.yaml
   
   

   File content:

   apiVersion: apps/v1
   kind: Deployment
   metadata:
     name: nginx
   spec:
     replicas: 1
     selector:
       matchLabels:
         app: nginx
     template:
       metadata:
         labels:
           app: nginx
       spec:
         containers:
         - image: nginx:latest
           name: nginx
         imagePullSecrets:
         - name: default-secret
   
   

3. Create and edit the nginx-nodeport-svc.yaml file to configure Service parameters. nginx-nodeport-svc.yaml is an example file name. You can rename it as needed.

   vi nginx-nodeport-svc.yaml
   
   

   File content:

   apiVersion: v1
   kind: Service
   metadata:
     labels:
       app: nginx
     name: nginx-nodeport
   spec:
     ports:
     - name: service
       nodePort: 30000     # Node port. The value ranges from 30000 to 32767.
       port: 8080          # Port for accessing a Service
       protocol: TCP       # Protocol used for accessing a Service. The value can be TCP or UDP.
       targetPort: 80      # Port used by a Service to access the target container. This port is closely related to the applications running in a container. In this example, the Nginx image uses port 80 by default.
     selector:             # Label selector. A Service selects a pod based on the label and forwards the requests for accessing the Service to the pod. In this example, select the pod with the app:nginx label.
       app: nginx
     type: NodePort        # Service type. NodePort indicates that the Service is accessed through a node port.
   
   

4. Create a workload.

   kubectl create -f nginx-deployment.yaml
   
   

   If information similar to the following is displayed, the workload has been created:

   deployment/nginx created
   
   

   Check the created workload.

   kubectl get pod
   
   

   If information similar to the following is displayed, the workload is running:

   NAME                     READY     STATUS             RESTARTS   AGE
   nginx-2601814895-znhbr   1/1       Running            0          15s
   
   

5. Create a Service.

   kubectl create -f nginx-nodeport-svc.yaml
   
   

   If information similar to the following is displayed, the Service is being created:

   service/nginx-nodeport created
   
   

   Check the created Service.

   kubectl get svc
   
   

   If information similar to the following is displayed, the Service has been created:

   # kubectl get svc
   NAME             TYPE        CLUSTER-IP     EXTERNAL-IP   PORT(S)          AGE
   kubernetes       ClusterIP   10.247.0.1     <none>        443/TCP          4d8h
   nginx-nodeport   NodePort    10.247.30.40   <none>        8080:30000/TCP   18s
   
   

6. Access the Service. By default, a NodePort Service can be accessed using IP-address-of-any-node:node-port. Cloud servers within the same VPC or containers within the cluster can access the Service. If an EIP is bound to a node, you can also use the EIP to access the Service.

   Create a container in the cluster and access it using IP-address-of-the-node:node-port.

   1. Obtain the node's IP address.

      kubectl get node -owide
      
      

      Command output:

      NAME           STATUS   ROLES    AGE    INTERNAL-IP    EXTERNAL-IP   OS-IMAGE                KERNEL-VERSION                CONTAINER-RUNTIME
      10.100.0.136   Ready    <none>   152m   10.100.0.136   <none>        CentOS Linux 7 (Core)   3.10.0-1160.25.1.el7.x86_64   docker://18.9.0
      10.100.0.5     Ready    <none>   152m   10.100.0.5     <none>        CentOS Linux 7 (Core)   3.10.0-1160.25.1.el7.x86_64   docker://18.9.0
      
      

   2. Create a pod and access its container.

      kubectl run -i --tty --image nginx:alpine test --rm /bin/sh
      
      

   3. Run the curl command to access the Service.

      curl 10.100.0.136:30000
      
      

      Command 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><em>Thank you for using nginx.</em></p>
      </body>
      </html>
      / #