Run a Stateless Application Using a Deployment [page]deterministic
This page shows how to run an application using a Kubernetes Deployment object.
##
- Create an nginx deployment.
- Use kubectl to list information about the deployment.
- Update the deployment.
##
## 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:1.14.2 Docker image:
1. Create a Deployment based on the YAML file:
```shell kubectl apply -f https://k8s.io/examples/application/deployment.yaml ```
1. Display information about the Deployment:
```shell kubectl describe deployment nginx-deployment ```
The output is similar to this:
``` Name: nginx-deployment Namespace: default CreationTimestamp: Tue, 30 Aug 2016 18:11:37 -0700 Labels: app=nginx Annotations: deployment.kubernetes.io/revision=1 Selector: app=nginx Replicas: 2 desired | 2 updated | 2 total | 2 available | 0 unavailable StrategyType: RollingUpdate MinReadySeconds: 0 RollingUpdateStrategy: 1 max unavailable, 1 max surge Pod Template: Labels: app=nginx Containers: nginx: Image: nginx:1.14.2 Port: 80/TCP Environment: <none> Mounts: <none> Volumes: <none> Conditions: Type Status Reason ---- ------ ------ Available True MinimumReplicasAvailable Progressing True NewReplicaSetAvailable OldReplicaSets: <none> NewReplicaSet: nginx-deployment-1771418926 (2/2 replicas created) No events. ```
1. List the Pods created by the deployment:
```shell kubectl get pods -l app=nginx ```
The output is similar to this:
``` NAME READY STATUS RESTARTS AGE nginx-deployment-1771418926-7o5ns 1/1 Running 0 16h nginx-deployment-1771418926-r18az 1/1 Running 0 16h ```
1. Display information about a Pod:
```shell 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 1.16.1.
1. Apply the new YAML file:
```shell kubectl apply -f https://k8s.io/examples/application/deployment-update.yaml ```
1. Watch the deployment create pods with new names and delete the old pods:
```shell kubectl get pods -l app=nginx ```
## Scaling the application by increasing the replica count
You can increase the number of Pods in your Deployment by applying a new YAML file. This YAML file sets `replicas` to 4, which specifies that the Deployment should have four Pods:
1. Apply the new YAML file:
```shell kubectl apply -f https://k8s.io/examples/application/deployment-scale.yaml ```
1. Verify that the Deployment has four Pods:
```shell kubectl get pods -l app=nginx ```
The output is similar to this:
``` NAME READY STATUS RESTARTS AGE nginx-deployment-148880595-4zdqq 1/1 Running 0 25s nginx-deployment-148880595-6zgi1 1/1 Running 0 25s nginx-deployment-148880595-fxcez 1/1 Running 0 2m nginx-deployment-148880595-rwovn 1/1 Running 0 2m ```
For detailed scaling procedures including scaling down and scaling to zero, see [Scale a Deployment Manually](/docs/tasks/run-application/scale-deployment/).
## Deleting a deployment
Delete the deployment by name:
```shell kubectl delete deployment nginx-deployment ```
## ReplicationControllers -- the Old Way
The preferred way to create a replicated application is to use a Deployment, which in turn uses a ReplicaSet. Before …(trimmed)