Python AWS Lambda Module Not Found

Question

I have an AWS Lambda implemented in Python 3.7 and deployed in a package arranged as below:

universe-UIFunctionCelestial-XXXX
|--universe-0-0-1-SNAPSHOT
| |--src
| | |--lambdas
| | | |--__init__.py
| | | |--celestial_persist_function.py
| | |--__init__.py

The following image shows this package as deployed in the AWS console:

The Lambda is accessible via API Gateway. Its GET method successfully invokes the Lambda, however the Lambda returns the following error:

Wed Mar 04 09:49:35 UTC 2020 : Endpoint response body before transformations: {"errorMessage": "Unable to import module 'universe-0-0-1-SNAPSHOT/src/lambdas/celestial_persist_function': No module named 'src'", "errorType": "Runtime.ImportModuleError"}

Wed Mar 04 09:49:35 UTC 2020 : Lambda execution failed with status 200 due to customer function error: Unable to import module 'universe-0-0-1-SNAPSHOT/src/lambdas/celestial_persist_function': No module named 'src'. Lambda request id: 381990d0-f193-4e49-b0fa-2c6d736552bd

Wed Mar 04 09:49:35 UTC 2020 : Method completed with status: 502

I was under the impression that the Python Lambda execution imports the lambda as a module, so I added __init__.py files at each level. Thes might help the lambda import as well as the imports within the lambda like:

from src.persistence.persistence_service import PersistenceService

Anyway, I have tried a number of different arrangements and file structures. What might I might be doing wrong?

Incidentally, all the code executes locally without any issues.

Ivan Shumov · Accepted Answer · 2020-03-04 10:31:10Z

0

I'm not experienced in Python, but looks like you should upload your code with another root folder. Please, try to move ..../src/ to /

P.S. And I recommend to use serverless.com framework to build your lambdas - it's much more easier for start

answered Mar 4, 2020 at 10:31

Ivan Shumov

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8 Comments

Michael Coxon Over a year ago

as I mentioned, I tried a number of arrangements, changing names and moving directories around was amongst them

Michael Coxon Over a year ago

ummm. yep, the serverless framework, I've been there about a year ago. Actually I used CloudFormation, which is AWS's own deployment method, I'd be rather surprised, however, if the choice of deployment framework made any difference to an internal python error.

Gareth McCumskey Over a year ago

The Serverless Framework (serverless.com) and CloudFormation are related but different. I recommend taking a look at the former. Makes deploying serverless applications to AWS much simpler.

Ivan Shumov Over a year ago

@MichaelCoxon actually, SF working on top of the CloudFormation. Please, check an example here serverless.com/framework/docs/providers/aws/examples/… If you still want to do it by yourself: try to move your functions in / and packages under /lib directory. Python just can't found target namespace under lambdas directory, I suppose

Michael Coxon Over a year ago

look, thanks guys about all your touts for SF, but I'd really love a solution to THIS problem please

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Anna Havelia · Accepted Answer · 2021-04-16 07:49:02Z

0

It's have been a while since the question was asked but I will answer it anyway - maybe it will help someone else.

I had the same issue - the thing with Lambda is that it runs inside the src folder and it does not understand your imports. What you need to have instead is:

    from [folder inside src] import [filename]

therefore your imports should look like this:

    from persistence import persistence_service

After this you will be able to invoke PersistenceService.

answered Apr 16, 2021 at 7:49

Anna Havelia

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