No logs from CMD when Python file can't load in Docker image

[davetapley]

Is your question related to a specific version? If so, please specify:

Docker image:

mcr.microsoft.com/azure-functions/python:4-python3.14

What language does your question apply to? (e.g. C#, JavaScript, Java, All)

Python

Question

With a Dockerfile like:

FROM mcr.microsoft.com/azure-functions/python:4-python3.14

ENV AzureWebJobsScriptRoot=/home/site/wwwroot \
    AzureFunctionsJobHost__Logging__Console__IsEnabled=true

COPY requirements.txt /
RUN pip install -r /requirements.txt

COPY function_app.py /home/site/wwwroot/

When add this to my function_app.py:

from azure.identity.aio import DefaultAzureCredential
credential = DefaultAzureCredential()

Running goes from this:

WEBSITES_INCLUDE_CLOUD_CERTS is not set to true.
info: Host.Triggers.Warmup[0]
      Initializing Warmup Extension.
info: Host.Startup[503]
...
info: Host.Startup[413]
      Host started (180ms)
info: Host.Startup[0]
      Job host started
Hosting environment: Production
Content root path: /
Now listening on: http://[::]:80
Application started. Press Ctrl+C to shut down.

to this:

WEBSITES_INCLUDE_CLOUD_CERTS is not set to true.
Hosting environment: Production
Content root path: /
Now listening on: http://[::]:80
Application started. Press Ctrl+C to shut down.

And trying to hit any endpoint results on Function host is not running..

---

In my case the underlying issue was not having aiohttp installed,
but it would be nice to have any log output whatsoever.

It doesn't even tell me there was a problem with function_app.py,
let alone what the problem was.

Invoking manually in the container I could see:

root@09ce4f921168:/# python /home/site/wwwroot/function_app.py 
Traceback (most recent call last):
  File "/opt/python/3/lib/python3.14/site-packages/azure/core/pipeline/transport/__init__.py", line 90, in __getattr__
    from ._aiohttp import AioHttpTransport
  File "/opt/python/3/lib/python3.14/site-packages/azure/core/pipeline/transport/_aiohttp.py", line 49, in <module>
    import aiohttp
ModuleNotFoundError: No module named 'aiohttp'

Can we have this output sent to stdout?

[AartBluestoke]

agreed - i have been affected by this (and other load time code issues) - the only workaround for this is to use the filesystem level realtime log connection from the azure portal, and try to catch the logs amongst the spam.