Use a NodePort service to expose an application

Deploy NGINX and create a NodePort Service to route external traffic to pods through node IPs.

Because edge deployments typically lack a load balancer, NodePort Services are a common way to expose applications outside the cluster.

Objectives

Deploy an NGINX application with two replicas in an ACK Edge cluster.
Create a NodePort Service to expose the application.
Access the application through a node IP and port.

Prerequisites

Ensure you have:

An ACK Edge cluster with at least one node
kubectl configured to connect to the cluster
Permissions to create Deployments and Services in the default namespace

Network constraints in ACK Edge clusters

Nodes in an ACK Edge cluster span multiple network domains, blocking cross-domain communication between nodes and pods:

To restrict traffic to backend pods on the current node or node pool, configure a Service topology.
To avoid port conflicts across network domains, configure port isolation per node pool (recommended) .

See Services quick start.

Deploy an application

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

apiVersion: apps/v1
kind: Deployment
metadata:
  name: nginx
  labels:
    app: nginx
spec:
  replicas: 2
  selector:
    matchLabels:
      app: nginx
  template:
    metadata:
      labels:
        app: nginx
    spec:
      containers:
      - name: nginx
        image: anolis-registry.cn-zhangjiakou.cr.aliyuncs.com/openanolis/nginx:1.14.1-8.6
        ports:
        - containerPort: 80

Apply the Deployment to create two NGINX pods:
```
kubectl apply -f nginx.yaml
```

Verify that both pods are running:

kubectl get deployment nginx

Expected output:

NAME       READY   UP-TO-DATE   AVAILABLE   AGE
nginx      2/2     2            2           43s

READY 2/2 confirms both replicas are up.

Create a NodePort Service

Create a file named nginx-svc.yaml with the following content:

apiVersion: v1
kind: Service
metadata:
  labels:
    app: nginx
  name: nginx-svc
  namespace: default
spec:
  ports:
  - port: 80          # Port exposed by the Service within the cluster
    protocol: TCP
    targetPort: 80    # Port on the pod that receives traffic
                      # nodePort is not set here; Kubernetes assigns one automatically (30000-32767)
  selector:
    app: nginx         # Must match spec.selector.matchLabels in nginx.yaml
  type: NodePort

Create the Service:
```
kubectl apply -f nginx-svc.yaml
```

Verify the Service and note the assigned node port:

kubectl get svc nginx-svc

Expected output:

NAME         TYPE        CLUSTER-IP        EXTERNAL-IP   PORT(S)        AGE
nginx-svc    NodePort    192.168.xxx.xxx   <none>        80:31309/TCP   3s

The number after the colon in PORT(S) (31309 here) is the node port.

Access the application through any node IP and the node port:
```
curl <Node-IP>:31309
```
Replace <Node-IP> with the node's IP address.

If the node is in a different network domain than your client, direct access may fail. Configure a Service topology or port isolation as described in Network constraints in ACK Edge clusters.

Clean up

To delete the resources you created:

kubectl delete svc nginx-svc
kubectl delete deployment nginx

Next steps

Configure a Service topology — restrict NodePort traffic to pods on the same node or node pool
Configure NodePort listening based on node pools — isolate node port ranges per node pool to prevent conflicts