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Exposing an External IP Address to Access an Application in a Cluster [page]deterministic

tutorials

This page shows how to create a Kubernetes Service object that exposes an external IP address.

##

* Install [kubectl](/docs/tasks/tools/). * Use a cloud provider like Google Kubernetes Engine or Amazon Web Services to create a Kubernetes cluster. This tutorial creates an [external load balancer](/docs/tasks/access-application-cluster/create-external-load-balancer/), which requires a cloud provider. * Configure `kubectl` to communicate with your Kubernetes API server. For instructions, see the documentation for your cloud provider.

##

* Run five 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.

## Creating a service for an application running in five pods

1. Run a Hello World application in your cluster:

```shell kubectl apply -f https://k8s.io/examples/service/load-balancer-example.yaml ``` The preceding command creates a [Deployment](#gloss:deployment) and an associated [ReplicaSet](#gloss:replica-set). The ReplicaSet has five [Pods](#gloss:pod) each of which runs the Hello World application.

1. Display information about the Deployment:

```shell kubectl get deployments hello-world kubectl describe deployments hello-world ```

1. Display information about your ReplicaSet objects:

```shell kubectl get replicasets kubectl describe replicasets ```

1. Create a Service object that exposes the deployment:

```shell kubectl expose deployment hello-world --type=LoadBalancer --name=my-service ```

1. Display information about the Service:

```shell kubectl get services my-service ```

The output is similar to:

```console NAME TYPE CLUSTER-IP EXTERNAL-IP PORT(S) AGE my-service LoadBalancer 10.3.245.137 104.198.205.71 8080/TCP 54s ```

The `type=LoadBalancer` service is backed by external cloud providers, which is not covered in this example. Please refer to [setting `type: LoadBalancer` for your Service](/docs/concepts/services-networking/service/#loadbalancer) for the details.

If the external IP address is shown as \<pending\>, wait for a minute and enter the same command again.

1. Display detailed information about the Service:

```shell kubectl describe services my-service ```

The output is similar to:

```console Name: my-service Namespace: default Labels: app.kubernetes.io/name=load-balancer-example Annotations: <none> Selector: app.kubernetes.io/name=load-balancer-example Type: LoadBalancer IP: 10.3.245.137 LoadBalancer Ingress: 104.198.205.71 Port: <unset> 8080/TCP NodePort: <unset> 32377/TCP Endpoints: 10.0.0.6:8080,10.0.1.6:8080,10.0.1.7:8080 + 2 more... Session Affinity: None Events: <none> ```

Make a note of the external IP address (`LoadBalancer Ingress`) exposed by your service. In this example, the external IP address is 104.198.205.71. Also note the value of `Port` and `NodePort`. In this example, the `Port` is 8080 and the `NodePort` is 32377.

1. In the preceding output, you can see that the service has several endpoints: 10.0.0.6:8080,10.0.1.6:8080,10.0.1.7:8080 + 2 more. These are internal addresses of the pods that are running the Hello World application. To verify these are pod addresses, enter this command:

```shell kubectl get pods --output=wide ```

The output is similar to:

```console NAME ... IP NODE hello-world-2895499144-1jaz9 ... 10.0.1.6 gke-cluster-1-default-pool-e0b8d269-1afc hello-world-2895499144-2e5uh ... 10.0.1.8 gke-cluster-1-default-pool-e0b8d269-1afc hello-world-2895499144-9m4h1 ... 10.0.0.6 gke-cluster-1-default-pool-e0b8d269-5v7a hello-world-2895499144-o4z13 ... 10. …(trimmed)

Sources

tutorials/stateless-application/expose-external-ip-address.md · docExposing an External IP Address to Access an Application in a Cluster

Related (8)

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references ReplicaSetReplicaSet conf=1
references PodPods conf=1
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part_of {{% heading "objectives" %}}describes conf=1
part_of {{% heading "cleanup" %}}describes conf=1
part_of {{% heading "whatsnext" %}}describes conf=1

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