Debugging AWS Lambda Invocations With An Echo Function

As I create architectures that include AWS Lambda functions, I find there are situations where I just want to know that the AWS Lambda function is getting invoked and to review the exact event data structure that is being passed in to it.

I found that a simple “echo” function can be dropped in to copy the AWS Lambda event to the console log (CloudWatch Logs). It’s easy to review this output to make sure the function is getting invoked at the right times and with the right data.

There are probably dozens of debug/echo AWS Lambda functions floating around out there, but for my own future reference, I have created a GitHub repo with a four line echo function that does the trick for me. I’ve included a couple scripts to install and uninstall the AWS Lambda function in an account, including the required IAM role and policies.

Here’s the repo for the lambda-echo AWS Lambda function:

The provides instructions on how to install and test.

Note: Once you install an AWS Lambda function, there is no reason to delete it if you think it might be useful in the future. It costs nothing to let Amazon store it for you and keep it available for when you want to run it again.

Amazon has indicated that they may prune AWS Lambda functions that go unused for long periods of time, but I haven’t seen this happen in practice yet.

Is there a standard file structure yet for a directory with AWS Lambda function source and the related IAM role/policies? Should I convert this to the format expected by Mitch Garnaat’s kappa perhaps?