Implement Metric Filter to profile memory usage for AWS Lambda Functions in AWS CloudFormation

Not long ago I came across the problem that I wanted to know in detail how much of the allocated memory my individual lambda functions consumes.

Since memory consumption is not part of the standard Lambda metrics, I had to find an individual solution.

Default AWS Lambda Metrics

As each lambda execution logs the memory usage I thought about implementing a metric filter extracting this information to create a custom metric in AWS CloudWatch.

AWS Lambda memory consumption log output

A sample metric filter was quickly found on the AWS forums (related thread).

You can test the metric filter by applying it to the log group of a lambda function like I did in the example below:

apply metric filter to log group

Now since verified the metric filter is actually working I only had to implement it in CloudFormation to be able to evaluate the memory consumption. It is important that a function name is defined so that the log group belonging to the Lambda function can also be created using the CloudFormation template.

You can find the template below:

Now you can find the memory consumption metric under StackName > LambdaFunctionName > Memory in AWS CloudWatch:

memory consumption result