An AWS Lambda function that handles application requests uses the default Lambda logging mechanism to log the timestamp, processing time, and status of requests. A developer needs to create Amazon…

CloudWatch Logs Insights is an interactive query tool for analyzing log data; it does not automatically publish metrics to a custom namespace on an ongoing basis.

CloudWatch RUM (Real User Monitoring) collects client-side performance data from browsers and is unrelated to server-side Lambda log processing.

Using CloudWatch Logs Insights with JSON-based queries allows ad-hoc analysis but still does not automatically publish ongoing metrics to a custom CloudWatch metrics namespace.

EMF enables Lambda functions to write specially structured JSON log statements that the CloudWatch Logs agent parses asynchronously to extract metric values. Because the namespace, metric name, and dimensions are embedded directly in the log format, CloudWatch automatically creates the metrics in the custom namespace without any additional configuration or manual metric publication calls.