Which Tool Should You Use?

B.

The correct tool to use in this scenario is Stackdriver Monitoring.

Stackdriver Monitoring is a Google Cloud Platform (GCP) tool that provides visibility into the performance, uptime, and overall health of cloud-powered applications. It collects metrics, events, and metadata from different GCP services, including App Engine, and presents them in an easy-to-use dashboard. This tool is designed to help you quickly identify and diagnose issues within your application by providing you with real-time and historical data.

In this scenario, the API is not behaving as expected, so the first step is to use Stackdriver Monitoring to monitor the application's performance over time. Stackdriver Monitoring provides metrics such as CPU usage, memory usage, and request latency, which can help you identify potential performance bottlenecks. By monitoring these metrics over time, you can detect any trends or patterns that could indicate an issue with your application code.

Once you have identified an issue, you can use Stackdriver Trace to trace the execution path of your application and identify any performance bottlenecks. Stackdriver Trace provides detailed information on the performance of individual requests, including the time spent on each function call, database query, and external API call. This information can help you identify the exact location in your code where the issue is occurring.

Stackdriver Debug Snapshots and Logpoints are other debugging tools that can be used to diagnose issues in your code. Debug Snapshots allow you to capture and analyze the state of your application at a specific point in time, while Logpoints allow you to add log statements to your code without redeploying your application. However, in this scenario, the focus is on monitoring the application over time, rather than diagnosing a specific issue, so Stackdriver Monitoring is the best tool for the job.