The following are typical use cases for Deployments:

Create a Deployment to rollout a ReplicaSet. The ReplicaSet creates Pods in the background. Check the status

of the rollout to see if it succeeds or not.

•

Declare the new state of the Pods by updating the PodTemplateSpec of the Deployment. A new ReplicaSet is

created and the Deployment manages moving the Pods from the old ReplicaSet to the new one at a

controlled rate. Each new ReplicaSet updates the revision of the Deployment.

•

Rollback to an earlier Deployment revision if the current state of the Deployment is not stable. Each rollback

updates the revision of the Deployment.

•

• Scale up the Deployment to facilitate more load.

Pause the rollout of a Deployment to apply multiple fixes to its PodTemplateSpec and then resume it to start

a new rollout.

•

• Use the status of the Deployment as an indicator that a rollout has stuck.

• Clean up older ReplicaSets that you don't need anymore

Notes:

If there are problem in deployment, k8s will automatically rollback to the previous version, however you can

explicitly rollback to a specific version, as in our case to revision 1 (the original pod version)

1.

You can rollback to a specific version by "--to-revision" option

i.e. Kubectl rollout undo deploy/deployment_name --to-revision=2

2.

3. The name of replicasets is always formatted as [deployment-name]-[random string]

4. Command: kubectl get deploy

When you inspect the deployment in your cluster the flowing field display

a. NAME: list the name of the deployment in the namespace

b. READY: ready/desired i.e. 2/2

c. UP-TO-DATE: display the no of replica that have been updated to achieve the desired state

d. AVAILABLE: Display how many replicas of the application are available to your users

e. AGE: Display the amount of time that app has been Running

Commands:

Create the Deployment by running the following command:

a. kubectl apply -f https://k8s.io/examples/controllers/nginx-deployment.yaml

1.

2. Run kubectl get deployments to check if the Deployment was created

3. To see the Deployment rollout status, run kubectl rollout status deployment/ubuntu-deployment

4. To see the ReplicaSet (rs) created by the Deployment, run kubectl get rs