website/docs/tutorials/stateless-application/run-stateless-application-deployment.md

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This page shows how to run an application using a Kubernetes Deployment object.

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{% capture objectives %}

• Create an nginx deployment.
• Use kubectl to list information about the deployment.
• Update the deployment.

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{% capture prerequisites %}

• To do this tutorial, you need a Kubernetes cluster, including a running Kubernetes API server. You can use an existing cluster, or you can create a new cluster. One way to create a new cluster is to use Minikube.

• You also need to have kubectl installed on your local machine, and kubectl must be configured to communicate with your Kubernetes API server. This configuration is done automatically if you use Minikube.

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Creating and exploring an nginx deployment

You can run an application by creating a Kubernetes Deployment object, and you can describe a Deployment in a YAML file. For example, this YAML file describes a Deployment that runs the nginx:1.7.9 Docker image:

{% include code.html language="yaml" file="deployment.yaml" ghlink="/docs/tutorials/stateless-application/deployment.yaml" %}

1. Create a Deployment based on the YAML file:

    export REPO=https://raw.githubusercontent.com/kubernetes/kubernetes.github.io/master
    kubectl create -f $REPO/docs/tutorials/stateless-application/deployment.yaml
   

2. Display information about the Deployment:

    kubectl describe deployment nginx-deployment
   
    user@computer:~/kubernetes.github.io$ kubectl describe deployment nginx-deployment
    Name:     nginx-deployment
    Namespace:    default
    CreationTimestamp:  Tue, 30 Aug 2016 18:11:37 -0700
    Labels:     app=nginx
    Selector:   app=nginx
    Replicas:   2 updated | 2 total | 2 available | 0 unavailable
    StrategyType:   RollingUpdate
    MinReadySeconds:  0
    RollingUpdateStrategy:  1 max unavailable, 1 max surge
    OldReplicaSets:   <none>
    NewReplicaSet:    nginx-deployment-1771418926 (2/2 replicas created)
    No events.
   

3. List the pods created by the deployment:

    kubectl get pods -l app=nginx
   
    NAME                                READY     STATUS    RESTARTS   AGE
    nginx-deployment-1771418926-7o5ns   1/1       Running   0          16h
    nginx-deployment-1771418926-r18az   1/1       Running   0          16h
   

4. Display information about a pod:

    kubectl describe pod <pod-name>
   

   where <pod-name> is the name of one of your pods.

Updating the deployment

You can update the deployment by applying a new YAML file. This YAML file specifies that the deployment should be updated to use nginx 1.8.

{% include code.html language="yaml" file="deployment-update.yaml" ghlink="/docs/tutorials/stateless-application/deployment-update.yaml" %}

1. Apply the new YAML file:

    kubectl apply -f $REPO/docs/tutorials/stateless-application/deployment-update.yaml
   

2. Watch the deployment create pods with new names and delete the old pods:

    kubectl get pods -l app=nginx
   

Deleting a deployment

Delete the deployment by name:

kubectl delete deployment nginx-deployment

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{% capture whatsnext %}

• Learn more about Deployment objects.

• Learn more about Deploying applications

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{% include templates/tutorial.md %}