No module named 'serverless_wsgi' on Azure

[MattiasDC]

I get the following error when using serverless-wsgi on Azure.

Exception while executing function: Functions.app Result: Failure
Exception: ModuleNotFoundError: No module named 'serverless_wsgi'
Stack: File "/azure-functions-host/workers/python/3.8/LINUX/X64/azure_functions_worker/dispatcher.py", line 238, in _handle__function_load_request
func = loader.load_function(
File "/azure-functions-host/workers/python/3.8/LINUX/X64/azure_functions_worker/loader.py", line 66, in load_function
mod = importlib.import_module(fullmodname)
File "/usr/local/lib/python3.8/importlib/init.py", line 127, in import_module
return _bootstrap._gcd_import(name[level:], package, level)
File "/home/site/wwwroot/wsgi_handler.py", line 22, in
import serverless_wsgi

When reading up on the python developer reference here, you can see that referring to a local module only works with explicit relative or absolute paths, but not implicit relative.

A fix might be to change line 22 of wsgi_handler.py to
from . import serverless_wsgi

I'm using serverless_wsgi version 1.7.5.

Note that running serverless locally with 'sls wsgi serve' works like a charm :)

[logandk]

Hi @MattiasDC,
Yeah, I've not tested on Azure personally - on AWS, the package root is PYTHONPATH, so it's not importing from a relative path and there's no issue.

Did you test that from . import serverless_wsgi works on Azure? And I assume you had to add __init__.py to the package root as well?

In that case, I suppose we catch the exception when importing from PYTHONPATH and fall back to the relative import. Another option would be to check whether PYTHONPATH is where wsgi_handler.py is and whether there's an __init__.py (assuming it's required), and import accordingly. I don't think we should add __init__.py automatically, but we should probably emit a warning if it's required on Azure and is not present in the project.

[MattiasDC]

Hi,

Putting the following code before the import fixes that problem (and the importing of the module containing the app).

root = os.path.abspath(os.path.dirname(__file__))
sys.path.insert(0, root)

There seem to be some other issues though, it seems Azure expects other function parameters.
An example Azure Function with WSGI can be found here.

[MattiasDC]

Hi @logandk,

I created a fork and got it working on Azure. In a nutshell:

• serverless_wsgi.py may be removed as azure provides a library to do this
• Re-implement wsgi_handler.handler.

If you were to add support for Azure, feel free to use my changes.
Make sure to let me know in that case.