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!

Asked By: Dr. Chocolate

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Source

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.

Answered By: Cecaro

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)

Answered By: Adam Easterling

Answer 3

You’ll have to:

Build you lambda layer using Docker:
sudo docker run -v "$PWD":/var/task "lambci/lambda:build-${penv}" /bin/sh -c "pip install -r requirements.txt -t python/lib/${penv}/site-packages/; exit"
Upload layer to AWS
Add layer to your lambda
Modity sys.path in your Lambda before import

    import sys; 
    sys.path.append('/opt/python/lib/python3.7/site-packages');
    import apsw
    print(apsw.__file__)

/opt/python/lib/python3.7/site-packages/apsw.cpython-37m-x86_64-linux-gnu.so

Update:
It looks like you need to place build under /opt/python so you can use it without
sys.path.append('/opt/python/lib/python3.7/site-packages');

New build steps:

mkdir -vp my-layer/python && cd my-layer/python
python3 -m pip install click -t ./ 
cd ..
zip -r9 my-layer python

now add layer to lambda function
and you can import:

import click

Answered By: Alex B

Answer 4

SOLUTION

You must to allocate all the packages you install with pip install … into a zip file that ends with the folllowing file structure:

[your zip file].zip
|_python/
  |_all.../
  |_your.../
  |_packages, modules.../

Another boring way is:

[your zip file].zip
|_python/
  |_lib/
    |_python3.x/
      |_site-packages/
        |_all.../
        |_your.../
        |_packages, modules.../

with this structure you lambda code get the modules you have.

I hope this make done your issue.

Answered By: niggue

How do I import a Python lambda layer?

Question:

Answers:

New build steps: