Pandas & NumPy with AWS Lambda

Fun fact: Pandas and NumPy don’t work out of the box with Lambda. The libraries that you might download from your development machine probably won’t work either.

The standard Lambda Python environment is very barebones by default. There is no point in loading in a bunch of libraries if they aren’t needed. This is why we package our Lambda functions into ZIP files to be deployed.

My first time attempting to use Pandas on AWS Lambda was in regards to concatenating Excel files. The point of this was to take a multi-sheet Excel file and combine it into one sheet for ingestion into a data lake. To accomplish this I used the Pandas library to build the new sheet. In order to automate the process I setup an S3 trigger on a Lambda function to execute the script every time a file was uploaded.

And then I ran into this error:

[ERROR] Runtime.ImportModuleError: Unable to import module 'your_module':
Importing the numpy c-extensions failed.

I had clearly added the NumPy library into my ZIP file:

So what was the problem? Well, apparently, the version of NumPy that I downloaded on both my Macbook and my Windows desktop is not compatible with Amazon Linux.

To resolve this issue, I first attempted to download the package files manually from I grabbed the latest “manylinux1_x86_x64.whl” file for both NumPy and Pandas. I put them back into my ZIP file and re-uploaded the file. This resulted in the same error.


The way to get this to work without failure is to spin up an Amazon Linux EC2 instance. Yes this seems excessive and it is. Not only did I have to spin up a new instance I had to install Python 3.8 because Amazon Linux ships with Python 2.7 by default. But, once installed you can use Pip to install the libraries to a directory by doing:

pip3 install -t . <package name>

This is useful for getting the libraries in the same location to ZIP back up for use. You can remove a lot of the files that are not needed by running:

rm -r *.dist-info __pycache__

After you have done the cleanup, you can ZIP up the files and move them back to your development machine, add your Lambda function and, upload to the Lambda console.

Run a test! It should work as you intended now!

If you need help with this please reach out to me on social media or leave a comment below.