Exam Professional Cloud Network Engineer topic 1 question 49 discussion

The correct answer is "D", see Canary Updates section from following link. https://cloud.google.com/compute/docs/instance-groups/rolling-out-updates-to-managed-instance-groups

"C" is correct. We perform a canary update if we have tested the new feature heavily. However, we have not tested heavily in this scenario. So we have to test the new feature and new template at first and have to MINIMIZE impacts to users. There are some impacts on users if there are some bugs on its template and we test on a canary update. There is no impact on users if we test the new instances in the new instance group which is not provided to users. So "D" has more impacts on users than "C". "C" is the least impactful way for users to test and update instances.

Canary updates are commonly used to minimize risk when deploying new features. This approach allows you to test the new template on a small subset of instances (canary instances) first before rolling it out to all instances. Thus, Option D provides the safest approach for updating your instances with minimal user impact.

D : You have an application that is running in a managed instance group. Your development team has released an updated instance template which contains a new feature which was not heavily tested. You want to minimize impact to users if there is a bug in the new template. How should you update your instances? A. Manually patch some of the instances, and then perform a rolling restart on the instance group. B. Using the new instance template, perform a rolling update across all instances in the instance group. Verify the new feature once the rollout completes. C. Deploy a new instance group and canary the updated template in that group. Verify the new feature in the new canary instance group, and then update the original instance group. D. Perform a canary update by starting a rolling update and specifying a target size for your instances to receive the new template. Verify the new feature on the canary instances, and then roll forward to the rest of the instances.

https://cloud.google.com/compute/docs/instance-groups/rolling-out-updates-to-managed-instance-groups#starting_a_canary_update

D seems sensible , as the question states minimize the impact . Using a canary update we can deploy the patch on some instances and roll back if any bugs found.

If you add two backends(instance groups) to LB, and not seperate them by url mapping, the traffic balancing will not work properly. This is based on my experience.

D -> https://cloud.google.com/compute/docs/instance-groups/rolling-out-updates-to-managed-instance-groups#starting_a_canary_update

D as targetSize is given in Canary updates

ans is D. https://cloud.google.com/compute/docs/instance-groups/rolling-out-updates-to-managed-instance-groups#canary_updates

What has this even got to do with PCNE? More like a PCA q for me.

Automated updates support up to two instance template versions in your MIG. This means that you can specify two different instance template versions for your group, which is useful for performing canary updates.

By deploying a new instance group and canarying the updated template, the impact of the new feature can be tested on a smaller scale before rolling out to the entire user base. This allows for any issues to be identified and resolved before a full rollout is performed. Once the new feature has been verified in the canary instance group, the original instance group can be updated to use the new template. This minimizes the risk of user impact and ensures that the new feature is thoroughly tested before being rolled out to all users.

• D. Perform a canary update by starting a rolling update ***** and specifying a target size for your instances to receive the new template. Verify the new feature on the canary instances, and then roll forward to the rest of the instances.

D A canary update is an update that is applied to a subset of instances in the group. With a canary update, you can test new features or upgrades on a random subset of instances, instead of rolling out a potentially disruptive update to all your instances. If an update is not going well, you only need to roll back the subset of instances, minimizing the disruption for your users.

ans - D

Answer is : D