Rollback

The Kubernetes cluster maintains the deployment history, so if the new deployed version is not working, we can roll back to the previous history available in the Kubernetes cluster.

kubectl rollout history deployment/deploymentdemo

deployment.apps/deploymentdemo

REVISION  CHANGE-CAUSE

1         <none>

2         <none>

3         <none>

In the above history, 

Revision #3 ---> contains poddemo-3.0

Revision #2 ---> contains poddemo-2.0

Revision #1 ---> contains poddemo-1.0

This is just to show that what version of container is deployed for Revision #3

kubectl describe deployments deploymentdemo

Name:                   deploymentdemo

Annotations:            deployment.kubernetes.io/revision: 3

Replicas:               4 desired | 4 updated | 4 total | 4 available | 0 unavailable

StrategyType:           RollingUpdate

    Image:        iam7hills/learnkubernetes:podsdemo-3.0

Rollout to the previous version

kubectl rollout undo deployment deploymentdemo --to-revision=2

deployment.apps/deploymentdemo rolled back

kubectl describe deployment deploymentdemo

Name:                   deploymentdemo

Namespace:              default

CreationTimestamp:      Sat, 23 Dec 2023 20:12:52 -0800

Labels:                 type=web

Annotations:            deployment.kubernetes.io/revision: 4

Selector:               type=web1

Replicas:               4 desired | 4 updated | 4 total | 4 available | 0 unavailable

StrategyType:           RollingUpdate

MinReadySeconds:        0

RollingUpdateStrategy:  1 max unavailable, 1 max surge

Pod Template:

  Labels:  type=web1

  Containers:

   podsdemo:

    Image:        iam7hills/learnkubernetes:podsdemo-2.0

kubectl rollout history deployment/deploymentdemo

deployment.apps/deploymentdemo

REVISION  CHANGE-CAUSE

1         <none>

3         <none>

4         <none>

If you notice here, revision #2, was removed as part of the rollback and it become revision #4 now.