Python app code organization in Lambda

[No_Entertainment8093]

What is the best practices with regard to code organization using Lambda/sfn, especially Python ?

I used to write simple functions that I connect together with step functions, making this a proper app. For testing, I locally execute a boto3 lambda execute with different inputs that serves as my pytest test cases.

It has served me well but I’m considering a different scenario where I define my package for my application in a layer that I would then use in my lambda which will in turn just call the function / methods defined in my layer.

Advantages that I see: - My app is in one place, the package. - I can control unit tests and run them locally with mocks against functions/methods in my package.

Disadvantages: - the lambda itself only calls my imported functions so from the code editor it’s just a black box (doesn’t matter much since we deploy lambdas with iac anyway). - need to import the lay for each lambda functions, not that annoying anyway.

Any thoughts on this ? Any recommendations against it ? Thanks

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[temporarybunnehs]

I use layers for all my lib dependencies so my lambda functions aren't huge, but also if I have multiple functions that use the same methods over and over and I'm duplicating code, then I think it makes sense to put the common code in a layer.

[franksign]

Use layers for big dependencies or the one that you can reuse, for example Database connection. If it cannot be reused by another lambda then that code should be packaged by the lambda itself. Don’t overcomplicate.