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This page shows how to create a Kubernetes Service object to that provides load-balanced access to an application running in a cluster.

Objectives

Before you begin

You need to have a Kubernetes cluster, and the kubectl command-line tool must be configured to communicate with your cluster. If you do not already have a cluster, you can create one by using Minikube.

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
    
  2. 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
    
  3. List the replica set for the two Hello World pods:

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

    The output is similar to this:

     NAME                     DESIRED   CURRENT   AGE
     hello-world-2189936611   2         2         12m
    
  4. Create a Serivice object that exposes the replica set:

     kubectl expose rs <your-replica-set-name> --type="LoadBalancer" --name="example-service"
    

    where <your-replica-set-name> is the name of your replica set.

  5. 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
    
  6. Use your Service object 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. Then 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.

Cleaning up

If you want to stop the Hello World application, enter these commands:

TODO

What’s next

Learn more about connecting applications with services.

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