# Use a Service to Access an Application in a Cluster

Use a Service to Access an Application in a ClusterThis page shows how to create a Kubernetes Service object that external clients can use to access an application running in a cluster. The Service provides load balancing for an application that has two running instances.Before you beginYou need to have a Kubernetes cluster, and the kubectl command-line tool must be configured to communicate with your cluster. It is recommended to run this tutorial on a cluster with at least two nodes that are not acting as control plane hosts. If you do not already have a cluster, you can create one by using minikube or you can use one of these Kubernetes playgrounds:iximiuz LabsKillercodaKodeKloudPlay with KubernetesObjectivesRun two instances of a Hello World application.Create a Service object that exposes a node port.Use the Service object to access the running application.Creating a service for an application running in two podsHere is the configuration file for the application Deployment:service/access/hello-application.yaml apiVersion: apps/v1 kind: Deployment metadata: name: hello-world spec: selector: matchLabels: run: load-balancer-example replicas: 2 template: metadata: labels: run: load-balancer-example spec: containers: - name: hello-world image: us-docker.pkg.dev/google-samples/containers/gke/hello-app:2.0 ports: - containerPort: 8080 protocol: TCP Run a Hello World application in your cluster: Create the application Deployment using the file above:kubectl apply -f https://k8s.io/examples/service/access/hello-application.yaml The preceding command creates a Deployment and an associated ReplicaSet. The ReplicaSet has two Pods each of which runs the Hello World application.Display information about the Deployment:kubectl get deployments hello-world kubectl describe deployments hello-world Display information about your ReplicaSet objects:kubectl get replicasets kubectl describe replicasets Create a Service object that exposes the deployment:kubectl expose deployment hello-world --type=NodePort --name=example-service Display information about the Service:kubectl describe services example-service The output is similar to this:Name: example-service Namespace: default Labels: run=load-balancer-example Annotations: <none> Selector: run=load-balancer-example Type: NodePort IP: 10.32.0.16 Port: <unset> 8080/TCP TargetPort: 8080/TCP NodePort: <unset> 31496/TCP Endpoints: 10.200.1.4:8080,10.200.2.5:8080 Session Affinity: None Events: <none> Make a note of the NodePort value for the Service. For example, in the preceding output, the NodePort value is 31496.List the pods that are running the Hello World application:kubectl get pods --selector="run=load-balancer-example" --output=wide The output is similar to this:NAME READY STATUS ... IP NODE hello-world-2895499144-bsbk5 1/1 Running ... 10.200.1.4 worker1 hello-world-2895499144-m1pwt 1/1 Running ... 10.200.2.5 worker2 Get the public IP address of one of your nodes that is running a Hello World pod. How you get this address depends on how you set up your cluster. For example, if you are using Minikube, you can see the node address by running kubectl cluster-info. If you are using Google Compute Engine instances, you can use the gcloud compute instances list command to see the public addresses of your nodes.On your chosen node, create a firewall rule that allows TCP traffic on your node port. For example, if your Service has a NodePort value of 31568, create a firewall rule that allows TCP traffic on port 31568. Different cloud providers offer different ways of configuring firewall rules.Use the node address and node port to access the Hello World application:curl http://<public-node-ip>:<node-port> where <public-node-ip> is the public IP address of your node, and <node-port> is the NodePort value for your service. The response to a successful request is a hello message:Hello, world! Version: 2.0.0 Hostname: hello-world-cdd4458f4-m47c8 Using a service configuration fileAs an alternative to using kubectl expose, you can use a service configuration file to create a Service.Cleaning upTo 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 What's nextFollow the Connecting Applications with Services tutorial.