Is it possible to share a piece of code betwen AWS Lambda functions?

Question

I am designing a serverless application with AWS Lambda. There's a piece of code on one of the functions that process the request in a certain way. I am going to make another function that's going to make the same processing with the request data, in the same way.

The problem is that, if I change the processing function in one of the Lambda functions, I'm going to have to copy the function and paste it into the other Lambda function. Every time I make a change I will have to do this. This will be even more cumbersome if I want to do the same processing function in more than two Lambda functions.

Is there a way to share pieces of code between Lambda functions, so I may respect DRY principles? Thanks.

Answer 1

Now you can use Layers to share libraries and code between your Functions.
It is possible to base more then one Function on one Layer.

You can create a zip file for the Layer pretty much the same way as you can do so for a Function. The only thing will be that all the common packages go to python/lib/python3.7/site-packages directory inside of zip and all your code goes to python directory.

So if you have file structure like this:

bundle.zip/
  python/
    common/
      __init__.py
      lib.py

Then from your Lambda Function's code you can reference it like this:

from common.lib import ...