Multiple region support in dimensions for a CloudFront distribution Lambda@Edge metrics in CloudWatch

Hello, thank you for raising your concern in the forum.

I am answering each concern below inline:

Query 1:"So, we need to know whether all the regions is possible for dimension 'Region' or only the 13 regions?"

Even though the portals of Cloudfront monitoring and Cloudwatch monitoring look similar the APIs in the backend are different.

In screenshot of Cloudwatch console- You are viewing Lambda metrics under Cloudfront "per distribution metrics". By design of Cloudwatch service, it only populates the data for the regions where error occurred in Lambda. In the screenshot you shared, error related to "LambdaExecutionError" occured only in regions "ap-south-1", "eu-west-2", "eu-central-1". This means that when user requests landed in regions "ap-south-1", "eu-west-2", "eu-central-1" the lambda code resulted in execution error[1].

[1]About lambda execution error: https://docs.aws.amazon.com/AmazonCloudFront/latest/DeveloperGuide/lambda-edge-testing-debugging.html#lambda-edge-testing-debugging-execution-errors

Even if you are using APIs to pull data in Cloudwatch, for Lambda@edge you should consider pulling data of the regions where error happened and ignore the regions which are not populated as errors did not happen there. Cloudwatch as a service, does not populate regions where the data for metric being tracked was not available.

Additionally, if you want to know verbose Lambda logs to understand the exact cause of "LambdaExecutionError", from the Cloudfront console monitoring you can follow below:

Cloudfront console---> monitoring---> lambda@edge(select your function)---> on the graphs locate the region--> click "view function logs"--> select the region--> Cloudwatch console will pop up with relevant logs

Reference: https://docs.aws.amazon.com/AmazonCloudFront/latest/DeveloperGuide/lambda-edge-testing-debugging.html

Query 2 : "Also, provide documentation for the metrics along with dimensions listed under CloudFront metrics. PFA."

Here is the document for metrics populated for Cloudfront service in Cloudwatch metrics section:

https://docs.aws.amazon.com/AmazonCloudFront/latest/DeveloperGuide/viewing-cloudfront-metrics.html#monitoring-console.distributions-additional

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