website/docs/tutorials/stateless-application/expose-external-ip-address-service.md

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This page shows how to create a Kubernetes Service object that external clients can use to access an application running in a cluster. The Service exposes a stable IP address and provides load balancing for an application that has two running instances.

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• Install kubectl.

• Create a Kubernetes cluster, including a running Kubernetes API server. One way to create a new cluster is to use Minikube.

• Configure kubectl to communicate with your Kubernetes API server. This configuration is done automatically if you use Minikube.

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• Run two instances of a Hello World application.
• Create a Service object that exposes an external IP address.
• Use the Service object to access the running application.

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Creating a service for an application running in two pods

1. Run a Hello World application in your cluster:

    kubectl run hello-world --replicas=2 --labels="run=load-balancer-example" --image=gcr.io/google-samples/node-hello:1.0  --port=8080
   

   The preceding command creates a Deployment object and an associated ReplicaSet object. The ReplicaSet has two Pods, each of which runs the Hello World application.

2. Display information about the Deployment:

    kubectl get deployments hello-world
    kubectl describe deployments hello-world
   

3. Display information about the ReplicaSet:

    kubectl get replicasets hello-world
    kubectl describe replicasets hello-world
   

4. List the pods that are running the Hello World application:

    kubectl get pods --selector="run=load-balancer-example"
   

   The output is similar to this:

    NAME                           READY     STATUS    RESTARTS   AGE
    hello-world-2189936611-8fyp0   1/1       Running   0          6m
    hello-world-2189936611-9isq8   1/1       Running   0          6m
   

5. Create a Service object that exposes the deployment:

    kubectl expose deployment hello-world --type="LoadBalancer" --name="example-service"
   

6. Display the IP addresses for your service:

    kubectl get services example-service
   

   The output shows the internal IP address and the external IP address of your service. If the external IP address shows as <pending>, repeat the command.

   Note: If you are using Minikube, you don't get an external IP address. The external IP address remains in the pending state.

   NAME              CLUSTER-IP   EXTERNAL-IP   PORT(S)    AGE
   example-service   10.0.0.160   <pending>     8080/TCP   40s
   

7. Use your service to access the Hello World application:

    curl <your-external-ip-address>:8080
   

   where <your-external-ip-address> is the external IP address of your service.

   The output is a hello message from the application:

    Hello Kubernetes!
   

   Note: If you are using Minikube, enter these commands:

    kubectl cluster-info
    kubectl describe services example-service
   

   The output displays the IP address of your Minikube node and the NodePort value for your service. Enter this command to access the Hello World application:

    curl <minikube-node-ip-address>:<service-node-port>
   

   where <minikube-node-ip-address> us the IP address of your Minikube node, and <service-node-port> is the NodePort value for your service.

Using a service configuration file

As an alternative to using kubectl expose, you can use a service configuration file to create a Service.

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To delete the Service, enter this command:

kubectl delete services example-service

To delete the Deployment, the ReplicaSet, and the Pods that are running the Hello World application, enter this command:

kubectl delete deployment hello-world

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Learn more about connecting applications with services. {% endcapture %}

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