Kubernetes Rolling Updates u0026 Zero-Downtime Deployments Quiz Quiz

Assess your grasp of Kubernetes rolling updates and strategies to achieve zero-downtime deployments. This quiz covers key principles, update mechanisms, and best practices for managing application availability during deployments.

1. Rolling Update Mechanism

   When performing a rolling update on a Kubernetes deployment with five replicas, how are new Pods introduced to ensure continuous service without downtime?

   1. Half of the new Pods are started before any are deleted
   2. All old Pods are deleted before starting new Pods
   3. New Pods are added one by one while old ones are terminated one by one
   4. New Pods are started only after all old Pods have terminated

   Explanation: A rolling update in Kubernetes gradually replaces instances of the old version with new ones to maintain continuous availability. The process introduces new Pods incrementally while simultaneously terminating old Pods, typically one by one, to avoid service disruption. Deleting all old Pods before launching new ones would cause downtime. Starting half or all of the new Pods before touching the old ones can lead to resource overuse or scheduling issues. Waiting until all old Pods have terminated before starting any new ones would also result in downtime.

2. Readiness Probes and Deployment

   Why is it important to configure readiness probes on containers during Kubernetes rolling updates?

   1. They signal when a container is ready to accept traffic
   2. They ensure containers are started after all others finish updating
   3. They shutdown containers gracefully during deletion
   4. They monitor container disk space during updates

   Explanation: Readiness probes notify Kubernetes when a container is ready to receive requests, which is crucial during rolling updates to ensure users are not routed to unresponsive or initializing Pods. If not configured, traffic may be sent to containers before they are ready, potentially causing errors. Ensuring containers are started after others, shutting down containers gracefully, or monitoring disk space are not their primary purposes. The other options describe unrelated or incorrect functions of readiness probes.

3. Update Strategies Comparison

   Which deployment strategy should you choose in Kubernetes to avoid any downtime but still allow for gradual rollout and quick rollback if problems occur?

   1. Canary deployment
   2. Blue-green deployment
   3. Rolling update
   4. Recreate strategy

   Explanation: The rolling update strategy gradually replaces old Pods with new ones, allowing quick rollback and minimizing downtime. Blue-green deployment enables zero downtime too but typically involves switching all traffic at once, not gradually. The recreate strategy deletes all existing Pods before starting new ones, causing a service gap. Canary deployment is gradual and good for testing, but by itself does not guarantee zero downtime unless specifically configured.

4. Handling Long Startup Times

   If your application takes longer than usual to start during a rolling update, what Kubernetes configuration can help prevent users from experiencing failed requests?

   1. Set the restartPolicy to OnFailure
   2. Increase the number of liveness probes
   3. Decrease the minimum available Pods
   4. Configure a longer readiness probe initial delay

   Explanation: A longer readiness probe initial delay provides enough startup time before the container is marked as ready and receives traffic, preventing premature request routing. Increasing liveness probes may cause unnecessary restarts, and setting the restartPolicy to OnFailure doesn't control when traffic is directed. Lowering the minimum available Pods reduces availability, which is counterproductive in this scenario.

5. Troubleshooting Rolling Update Failures

   During a rolling update, what is the likely outcome if a new Pod repeatedly fails its readiness probe, and how does Kubernetes respond?

   1. The rolling update is paused until the issue is resolved or rolled back
   2. The Pod is removed from the service and the update proceeds with other Pods
   3. All old Pods are terminated regardless of readiness
   4. The update immediately stops and all Pods are rolled back

   Explanation: Kubernetes pauses the rolling update when new Pods do not pass readiness probes, preventing further replacement of old Pods and avoiding service disruption. The system does not immediately roll back all Pods, nor does it terminate all old Pods regardless of readiness. Removing the non-ready Pod from the service without pausing the update would allow the update to proceed incorrectly. The pause ensures administrators can address the problem before proceeding or rolling back.