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Managing Updates and Rollbacks

  • Managing updates and rollbacks in Kubernetes is crucial to ensure smooth deployments and mitigate issues. This document discusses strategies for rolling updates and blue/green deployments, demonstrates the use of rollout commands to manage application updates, and covers performing rollbacks in case of issues.

Rolling Updates and Blue/Green Deployments

  • Rolling Updates: Rolling updates involve gradually replacing old instances of an application with new ones. This strategy ensures continuous availability during the update process. Kubernetes achieves rolling updates by creating new pods with the updated version and gradually terminating the old pods.

  • Blue/Green Deployments: Blue/green deployments involve creating a new environment ("blue") identical to the existing environment ("green") and routing traffic to the new environment once it's ready. This approach allows for zero-downtime deployments and provides a quick rollback option if issues arise.

Using Rollout Commands

  • Kubernetes provides rollout commands to manage application updates:

  • kubectl set: Use the kubectl set command to update specific properties of a resource. For example, to update the image of a deployment:

kubectl set image deployment/<deployment-name> <container-name>=<new-image>
  • kubectl rollout: The kubectl rollout command provides fine-grained control over the rollout process. Common commands include:
    • kubectl rollout status: Check the status of a rollout.
    • kubectl rollout pause: Pause a rollout to investigate issues.
    • kubectl rollout resume: Resume a paused rollout.
    • kubectl rollout history: View the revision history of a deployment.
    • kubectl rollout undo: Rollback to a previous revision.

Performing Rollbacks

  • If issues arise during a deployment, you can perform a rollback to a previous working state:

  • Use the kubectl rollout undo command to initiate a rollback. By default, it rolls back to the previous revision:

kubectl rollout undo deployment/<deployment-name>
  • Verify the status of the rollback and monitor the deployment until it stabilizes:
kubectl rollout status deployment/<deployment-name>
  • Rollbacks can also be performed by specifying a specific revision or using kubectl rollout undo with the --to-revision flag.

Additional Resources

By following strategies for rolling updates and blue/green deployments, using rollout commands to manage updates, and being prepared to perform rollbacks, you can ensure smooth deployments and effectively handle issues in Kubernetes.