The correct answer is A. Select a latency metric for a request-based method of evaluation.

A latency metric measures how responsive your service is to users.For example, you can use thecloud.googleapis.com/http/server/response_latenciesmetric to measure the latency of HTTP requests to your service1. A request-based method of evaluation counts the number of successful requests that meet a certain criterion, such as being below a latency threshold, and compares it to the number of all requests.For example, you can define an SLI as the ratio of requests with latency below 300 ms to all requests2. A request-based method of evaluation is suitable for measuring performance over time, such as per calendar month.You can set an SLO for the SLI to be at least 90%, which means that you expect 90% of the requests to have latency below 300 ms in a month3.

Cloud Build Private Pools allow your builds to run in a secure, isolated environment with direct access to resources inside your private VPC network , without exposing them to the public internet. This is the Google-recommended approach for minimizing management overhead while maintaining strong security boundaries.

From the official documentation:

" Private pools run your builds in a dedicated and secure environment that can connect to private network resources. "

— Cloud Build Private Pools Overview

" You can configure private pools to access resources in a VPC network, which enables secure access to services without using public IPs. "

— Accessing Private Resources

This method eliminates the need to create and manage additional compute instances or complex load balancing setups, providing seamless integration with your private services during CI pipeline execution.

The best option for giving developers the ability to test the latest revisions of the service before the service is exposed to customers is to run the gcloud run deploy booking-engine --no-traffic --tag devcommand and use the https://dev----booking-engine-abcdef.a.run.app URL for testing. The gcloud run deploy command is a command that deploys a new revision of your service or updates an existing service. By using the --no-traffic flag, you can prevent any traffic from being sent to the new revision. By using the --tag flag, you can assign a tag to the new revision, such as dev. This way, you can create a new revision of your service without affecting your customers. You can also use the tag-based URL (e.g., https://dev----booking-engine-abcdef.a.run.app) to access and test the new revision.

 The best option for mitigating the incident impact on users and enabling the developers to troubleshoot the issue is to change the selector on the Service app-svc to app: my-app, version: blue. A Service is a resource that defines how to access a set of Pods. A selector is a field that specifies which Pods are selected by the Service. By changing the selector on the Service app-svc to app: my-app, version: blue, you can ensure that the Service only routes traffic to the Pods that have both labels app: my-app and version: blue. These Pods belong to the Deployment app-blue, which uses the previous version of the application. This way, you can mitigate the incident impact on users by switching back to the working version of the application. You can also enable the developers to troubleshoot the issue with the new version of the application in the Deployment app-green without affecting users.

The best deployment model for releasing a new version of your application in GKE with the ability to instantly roll back to the previous version is to perform a blue/green deployment and test your new application after the deployment is complete. A blue/green deployment is a deployment strategy that involves creating two identical environments, one running the current version of the application (blue) and one running the new version of the application (green). The traffic is switched from blue to green after testing the new version, and if any issues are discovered, the traffic can be switched back to blue instantly. This way, you can minimize downtime and risk during deployment.

https://cloud.google.com/build/docs/securing-builds/use-encrypted-credentials

Rollback to previous stable version. Then you need to find what is causing the issue.