How do I import a Python lambda layer?

Question

I have a file with this as the contents.

def print_hello_world():
    print ('Hello World')

It's zipped up in a folder with a __init__.py file.

I add this as the layer and set the correct runtime of python3.6.

How do import it into my lambda function via lambda code?

Edit: After researching I found that lambda mounts the layers at /opt and if you add /opt to your syspath via sys.path.insert(0, '/opt') then you can import your layers.

You can see your layers at: print(os.listdir("/opt"))

There's gotta be a more elegant way to do this!

Answer 1

So I've recently ran into this issue, and I believe I found a cleaner way to import your layers.

First for the structure of the zip file which you upload:

• You do not need an __init__.py file
• Put all the scripts which you want to import into a folder name python
• Zip up that python folder (choose any name you want) and upload it to your layer
• Once uploaded, and the layer has been configured in your lambda function, you can simply use it with import {filename}

So if your script in the python folder was called something like custom_helper.py, import it in your lambda with import custom_helper.

I am not sure if this is the clean way to do it, but it seems simple enough to start.

Answer 2

Your zip file should have the following structure:

python/lib/python3.7/site-packages

That is, it needs a folder named Python, and within that a folder named lib, and within that a folder named python3.7, and within that a folder named site-packages. Anything inside that folder will be available for import.

(If you're using another version of Python, that version should be in the path instead of 3.7)