Running Node Port Service on Kubernetes

 We will be running the below deployment.yaml on minikube.

apiVersion: apps/v1
kind: Deployment
metadata:
 name: helloweb
 labels:
   app: hello
spec:
 selector:
   matchLabels:
     app: hello
 template:
   metadata:
     labels:
       app: hello
   spec:
     containers:
     - name: hello-app
       image: gcr.io/google-samples/hello-app:1.0
       ports:
       - containerPort: 8080

Applied above deployment using below command:

$ kubectl apply -f deployment.yaml
deployment.apps/helloweb created

Check the status using below command:

$ kubectl get all
NAME                            READY   STATUS    RESTARTS   AGE
pod/helloweb-5dfb8764bf-9k7ss   1/1     Running   0          9s

NAME                 TYPE        CLUSTER-IP   EXTERNAL-IP   PORT(S)   AGE
service/kubernetes   ClusterIP   10.96.0.1    <none>        443/TCP   86d

NAME                       READY   UP-TO-DATE   AVAILABLE   AGE
deployment.apps/helloweb   1/1     1            1           9s

NAME                                  DESIRED   CURRENT   READY   AGE
replicaset.apps/helloweb-5dfb8764bf   1         1         1       9s

This will create helloweb application.

We will expose the above application using node port service. The node port service opens a port on node and maps it to node/cluster ip.

apiVersion: v1
kind: Service
metadata:
  name: helloweb-svc
  labels:
    app: hello
spec:
  type: NodePort
  ports:
  - port: 9080
    targetPort: 8080
  selector:
    app: hello

This maps the application target port 8080 to port 9080.

Create node port service using below command:

$  kubectl apply -f service-nodeport.yaml
service/helloweb-svc created

 

Check the status using below command:

$ kubectl get all
NAME                            READY   STATUS    RESTARTS   AGE
pod/helloweb-5dfb8764bf-9k7ss   1/1     Running   0          52s

NAME                   TYPE        CLUSTER-IP    EXTERNAL-IP   PORT(S)          AGE
service/helloweb-svc   NodePort    10.97.186.9   <none>        9080:31467/TCP   4s
service/kubernetes     ClusterIP   10.96.0.1     <none>        443/TCP          87d

NAME                       READY   UP-TO-DATE   AVAILABLE   AGE
deployment.apps/helloweb   1/1     1            1           52s

NAME                                  DESIRED   CURRENT   READY   AGE
replicaset.apps/helloweb-5dfb8764bf   1         1         1       52s        

The node port service maps the 9080 to 8080 using node port 31647.

We can see the application in browser by port forwarding to 7080 using below command:

$  kubectl port-forward service/helloweb-svc 7080:9080
Forwarding from 127.0.0.1:7080 -> 8080
Forwarding from [::1]:7080 -> 8080
Handling connection for 7080

Open the browser  http://localhost:7080/ :

You can also access using minikube service command:

$   minikube service helloweb-svc
|-----------|--------------|-------------|---------------------------|
| NAMESPACE |     NAME     | TARGET PORT |            URL            |
|-----------|--------------|-------------|---------------------------|
| default   | helloweb-svc |        9080 | http://192.168.49.2:31467 |
|-----------|--------------|-------------|---------------------------|
🏃  Starting tunnel for service helloweb-svc.
|-----------|--------------|-------------|------------------------|
| NAMESPACE |     NAME     | TARGET PORT |          URL           |
|-----------|--------------|-------------|------------------------|
| default   | helloweb-svc |             | http://127.0.0.1:56345 |
|-----------|--------------|-------------|------------------------|
🎉  Opening service default/helloweb-svc in default browser...
❗  Because you are using a Docker driver on darwin, the terminal needs to be open to run it.

This will open browser and run the service.

Running it on GKE:

We can create a cluster using below command:

$  gcloud container clusters create hello-cluster --num-nodes=1 --zone "us-central1-c" --project "jovial-honor-327604"

Once the cluster is created open terminal and run below command:

$  gcloud container clusters get-credentials hello-cluster --zone "us-central1-c"

Create deployment and service using above steps. This will launch the service with External-IP you can use this node IP to access the service from the browser by opening the node port on the firewall.

$  kubectl get service helloweb-svc --output yaml

spec:
    ...
    ports:
    - nodePort: 30876  # external-ip; http://ip-1:30876; http://ip-2:30876 ....
      port: 80         # cluster-ip:port; http://cluster-ip:80/
      protocol: TCP
      targetPort: 8080 # application port
    selector:

using the NodePort from above to open firewall:

$  gcloud compute firewall-rules create test-node-port --allow tcp:NODE_PORT

Access your Service

In your browser's address bar, enter the following:

NODE_IP_ADDRESS:NODE_PORT

Happy Coding !!!