How do I properly structure AWS Lambda Python Layer to avoid Import Errors?

Question

I have a custom python layer in AWS Lambda with the structure:

/python
|_/m_utilities
  |_/functions
    |_/__init__.py
    |_/Defaults.py
    |_/Athena.py
  |_/parameterizer
    |_/classes
      |_/__init__.py
      |_/AthenaLite.py
      |_/BaseParameter.py
    |_/__init__.py
|_/misc

• The parameterizer init.py contains from parameterizer.classes.AthenaLite import athena_parameterizer as athena_lite

The lambda handler starts with:

from m_utilities.functions.Athena import <various functions>
from m_utilities.parameterizer import athena_lite

This structure works as expected locally, I'm able to import everything with no issues. When I attempt to test the lambda however I get the error: [ERROR] Runtime.ImportModuleError: Unable to import module 'parameterizer'

When attempting to debug, one of the things I tried was editing the lambda handler to examine the folder structure (which looks correct) and printing off the modules within the m_utilities package to see if my 'parameterizer' module exists there.

This in the lambda handler:

try:
    from m_utilities.parameterizer import athena_lite
except:
    import os.path, pkgutil,m_utilities
    pkgpath = os.path.dirname(fp_utilities.__file__)
    print([name for _, name, _ in pkgutil.iter_modules([pkgpath])])

Returns in AWS:

['functions', 'messaging', 'parameterizer', 'misc']

The module appears to be there, so what am I doing incorrectly that it is unable to import it?

Answer 1

For some reason, I'm not sure why, this structure worked in AWS:

/python
|_/m_utilities
  |_/functions
    |_/__init__.py
    |_/Defaults.py
    |_/Athena.py
|_/parameterizer
  |_/classes
    |_/__init__.py
    |_/AthenaLite.py
    |_/BaseParameter.py
  |_/__init__.py
|_/misc

I moved the 'parameterizer' module into the top-level folder, and from parameterizer import athena_lite worked.