A Lambda function logs timestamps, processing times, and request statuses using the default Lambda logging (CloudWatch Logs). You need to create CloudWatch metrics from those logs and publish them under a custom CloudWatch metrics namespace. Which approach meets these requirements?

The correct approach is to format the log statements using the CloudWatch embedded metric format (EMF). EMF allows you to embed custom metrics directly within your CloudWatch Logs events. When Lambda logs these EMF-formatted messages to CloudWatch Logs, CloudWatch automatically extracts the metrics and publishes them to the specified custom namespace, eliminating the need for separate metric creation steps. This is the most efficient and recommended way to create custom metrics from application logs in AWS. Using CloudWatch Logs Insights to generate custom metrics (whether via EMF or JSON parsing) is incorrect because Logs Insights is a query and analysis service, not a mechanism for generating metrics directly from incoming log streams for continuous monitoring. Amazon CloudWatch RUM (Real User Monitoring) is designed for monitoring client-side web application performance, not for processing backend Lambda function logs.