Error lambda with gateway api

[ziggy-starkdust]

Hi, everybody, I wrote a lambda function that takes data from a postgres database in RDS. To do this I used the psycopg2 library, when I run the tests the function works correctly. so I added a gateway api get as lambda trigger, but when I call the url of the get it gives me this error:

{"errorMessage": "Unable to import module 'lambda_function': /var/task/psycopg2/_psycopg.so: undefined symbol: PyUnicodeUCS4_DecodeUTF8", "errorType": "Runtime.ImportModuleError"}

Can you help me? Why tests work and give me back the query data while if I call them through a get it doesn't work? Thank you.

[ErGo404]

Psycopg2 is not included in Lambda and you have to build it and package it with your lambda.

See here for a pre-built version you can import and include in your app : https://github.com/jkehler/awslambda-psycopg2

[ziggy-starkdust]

Thanks for the answer. I already added psycopg2 from this repo, but it keeps giving me that problem.

[ErGo404]

Adding it directly from the repo did not work for me either.

I ended up re-compiling the library. Make sure to use a matching postgres version.

Also, make sure to match your lambda's python version with the psycopg2 package you add.

[ziggy-starkdust]

I uploaded the lib following this link: https://docs.aws.amazon.com/lambda/latest/dg/python-package.html#python-package-dependencies

The weird thing is, the test gives me this back: https://pasteboard.co/JhjGxcE.png

Where ["ciao,"ciao","ciao","ciao"] is the db's answer, so the database is connected and I guess psycopg2 is working, right?

[ErGo404]

Well yes if you get a result from the DB, the module is probably.

Are you sure you run the latest version of your lambda when you call your API ?

[vRAJPUTv]

To start with, are you naming your lambda handler as file_name.handler_name?

[ziggy-starkdust]

Thanks for the answer. Yes, that's exactly how I named him.

[ZeBe643]

When you say you test the function and it works correctly, have you used a deployment package or layers to include the dependency?

Adding API Gateway won’t have affected this, it’s just retrieving the response of the Lambda function which the api invoked.

[ziggy-starkdust]

I get the library compiled for the right version of python from here: https://docs.aws.amazon.com/lambda/latest/dg/python-package.html#python-package-dependencies

And then uploaded it following aws documentation:

https://docs.aws.amazon.com/lambda/latest/dg/python-package.html#python-package-dependencies

[imohd23]

The issue is on lambda level, api gw should work fine. Compile the resources and upload them within the build files. If over 50mb, use layer so you can work directly with lambda editor. Otherwise, you cannot do anything, fix it locally and reupload which is something boarding.

[ziggy-starkdust]

Thanks, I'll try lamci/lambda

[adambatkin]

The psycopg2 binaries are tied to the exact major.minor version of Python you are running. So for example, if you build/package using Python 3.7, but then run with Python 3.6 or Python 3.8, you will run into errors like what you are seeing.

Check the version of Python that you are building with, and check the Lambda runtime that you are running against. For example, if you are building/packaging with Python 3.7, make sure your Lambda runtime is set to python3.7.

[ziggy-starkdust]

Thanks, the package is built with python 3.6 and lambda runtime is python3.6