Rolling Updated & Rollbacks

The commands of deployment

Create

• kubectl create:
  • kubectl create -f <deployment_file>.yaml
• kubectl run:
  • kubectl run <deployment_name> --image=<image_name>

Get

• kubectl get deployments

Update

• kubectl apply -f <deployment_file>.yaml
• kubectl set image deployment/<deployment_name> key=value: the file is unchanged.
• How it works?
  • destory the old replica-set
  • create a new replica-set

Check Status

• kubectl rollout status deployment/<deployment_name>
• kubectl rollout history deployment/<deployment_name> --version=<version>

Rollout

• When you create a deployment, it trigger a rollout, and it create a revision.
• kubectl rollout status deployment/<deployment_name>
• Deployment Strategy:
  • Recreate: Destroy all of the all versions -> application down -> create new version
  • Rolling Update: Deafult. Destory and create pod one by one, so that the application will keep running if you have more than one pod.
• If the new pod is unvailable, k8s will not terminate the old one.

Rollback

• Command line: kubectl rollout undo deployment/<deployment_name>
• How it works?
  • Destory the new replica-set
  • create the old replica-set