You are tasked with augmenting the observability of a serverless function to ensure granular tracking of its execution time when processing streaming data. How would you enable systematic tracking of the function's processing duration to aid in swift identification and remediation of performance bottlenecks?
Depend exclusively on the standard metrics offered by the serverless platform for average processing times without modifications.
Configure an alert based on a heuristic evaluation of the serverless platform's function execution duration.
Manually record log entries for execution times, and later process them with an external application to transform into structured metrics.
Utilize the embedded metric format for custom metrics creation within your serverless application logic.