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* Revise Pod concept Adapt the existing Pod documentation to suit the Docsy theme, by promoting the Pod concept itself to /docs/concepts/workloads/pods/ Following on from this, update the Pod Lifecycle page to cover the lifecycle of a Pod and follow on directly from the Pod concept, for readers keen to understand things in detail. This change also removes the automatic contents list from the Pod overview page. Instead, the new page links to all the pages inside the Pod section. * Update links to Pod concept Link to updated content * Incorporate Pod concept suggestions Co-authored-by: Celeste Horgan <celeste@cncf.io> * Revise StatefulSet suggestion for Pod concept Co-authored-by: Celeste Horgan <celeste@cncf.io> Co-authored-by: Celeste Horgan <celeste@cncf.io>
177 lines
5.4 KiB
Markdown
177 lines
5.4 KiB
Markdown
---
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title: Exposing an External IP Address to Access an Application in a Cluster
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content_type: tutorial
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weight: 10
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---
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<!-- overview -->
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This page shows how to create a Kubernetes Service object that exposes an
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external IP address.
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## {{% heading "prerequisites" %}}
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* Install [kubectl](/docs/tasks/tools/install-kubectl/).
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* Use a cloud provider like Google Kubernetes Engine or Amazon Web Services to
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create a Kubernetes cluster. This tutorial creates an
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[external load balancer](/docs/tasks/access-application-cluster/create-external-load-balancer/),
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which requires a cloud provider.
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* Configure `kubectl` to communicate with your Kubernetes API server. For
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instructions, see the documentation for your cloud provider.
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## {{% heading "objectives" %}}
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* Run five instances of a Hello World application.
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* Create a Service object that exposes an external IP address.
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* Use the Service object to access the running application.
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<!-- lessoncontent -->
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## Creating a service for an application running in five pods
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1. Run a Hello World application in your cluster:
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{{< codenew file="service/load-balancer-example.yaml" >}}
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```shell
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kubectl apply -f https://k8s.io/examples/service/load-balancer-example.yaml
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```
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The preceding command creates a
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{{< glossary_tooltip text="Deployment" term_id="deployment" >}}
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and an associated
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{{< glossary_tooltip term_id="replica-set" text="ReplicaSet" >}}.
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The ReplicaSet has five
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{{< glossary_tooltip text="Pods" term_id="pod" >}}
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each of which runs the Hello World application.
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1. Display information about the Deployment:
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kubectl get deployments hello-world
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kubectl describe deployments hello-world
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1. Display information about your ReplicaSet objects:
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kubectl get replicasets
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kubectl describe replicasets
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1. Create a Service object that exposes the deployment:
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kubectl expose deployment hello-world --type=LoadBalancer --name=my-service
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1. Display information about the Service:
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kubectl get services my-service
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The output is similar to this:
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NAME TYPE CLUSTER-IP EXTERNAL-IP PORT(S) AGE
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my-service LoadBalancer 10.3.245.137 104.198.205.71 8080/TCP 54s
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{{< note >}}
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The `type=LoadBalancer` service is backed by external cloud providers, which is not covered in this example, please refer to [this page](/docs/concepts/services-networking/service/#loadbalancer) for the details.
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{{< /note >}}
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{{< note >}}
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If the external IP address is shown as \<pending\>, wait for a minute and enter the same command again.
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{{< /note >}}
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1. Display detailed information about the Service:
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kubectl describe services my-service
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The output is similar to this:
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Name: my-service
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Namespace: default
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Labels: app.kubernetes.io/name=load-balancer-example
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Annotations: <none>
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Selector: app.kubernetes.io/name=load-balancer-example
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Type: LoadBalancer
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IP: 10.3.245.137
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LoadBalancer Ingress: 104.198.205.71
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Port: <unset> 8080/TCP
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NodePort: <unset> 32377/TCP
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Endpoints: 10.0.0.6:8080,10.0.1.6:8080,10.0.1.7:8080 + 2 more...
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Session Affinity: None
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Events: <none>
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Make a note of the external IP address (`LoadBalancer Ingress`) exposed by
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your service. In this example, the external IP address is 104.198.205.71.
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Also note the value of `Port` and `NodePort`. In this example, the `Port`
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is 8080 and the `NodePort` is 32377.
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1. In the preceding output, you can see that the service has several endpoints:
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10.0.0.6:8080,10.0.1.6:8080,10.0.1.7:8080 + 2 more. These are internal
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addresses of the pods that are running the Hello World application. To
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verify these are pod addresses, enter this command:
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kubectl get pods --output=wide
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The output is similar to this:
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NAME ... IP NODE
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hello-world-2895499144-1jaz9 ... 10.0.1.6 gke-cluster-1-default-pool-e0b8d269-1afc
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hello-world-2895499144-2e5uh ... 10.0.1.8 gke-cluster-1-default-pool-e0b8d269-1afc
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hello-world-2895499144-9m4h1 ... 10.0.0.6 gke-cluster-1-default-pool-e0b8d269-5v7a
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hello-world-2895499144-o4z13 ... 10.0.1.7 gke-cluster-1-default-pool-e0b8d269-1afc
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hello-world-2895499144-segjf ... 10.0.2.5 gke-cluster-1-default-pool-e0b8d269-cpuc
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1. Use the external IP address (`LoadBalancer Ingress`) to access the Hello
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World application:
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curl http://<external-ip>:<port>
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where `<external-ip>` is the external IP address (`LoadBalancer Ingress`)
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of your Service, and `<port>` is the value of `Port` in your Service
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description.
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If you are using minikube, typing `minikube service my-service` will
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automatically open the Hello World application in a browser.
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The response to a successful request is a hello message:
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Hello Kubernetes!
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## {{% heading "cleanup" %}}
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To delete the Service, enter this command:
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kubectl delete services my-service
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To delete the Deployment, the ReplicaSet, and the Pods that are running
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the Hello World application, enter this command:
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kubectl delete deployment hello-world
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## {{% heading "whatsnext" %}}
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Learn more about
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[connecting applications with services](/docs/concepts/services-networking/connect-applications-service/).
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