Backend Web App "uvicorn" logger not working

[supplemarty]

Discussed in #818

^{Originally posted by supplemarty August 15, 2024}
The backend (and enrichment) web apps use the "uvicorn" logger as seen here:
log = logging.getLogger("uvicorn") log.setLevel('DEBUG') log.propagate = True

When I use this log variable in the backend code for debug tracing like:
log.debug("HELLO WORLD")
those log entries do not show up in the log stream NOR application insights but in the enrichment app this same pattern seems to be working fine.

I setup my own logger using the StreamHandler, and it works as I would expect. I cannot see where uvicorn is getting its logging dict configuration in the azure web app configuration. Thoughts?

[KronemeyerJoshua]

Python apps run on Azure App Service for Linux use a gunicorn WSGI by default.
https://learn.microsoft.com/en-us/azure/app-service/configure-language-python

By default the logging and debugging arguments are not set in the terraform

PubSec-Info-Assistant/infra/main.tf

Line 90 in f295135

appCommandLine = "gunicorn -w 4 -k uvicorn.workers.UvicornWorker app:app"

You can specify more commands in your app service where the gunicorn command is set and restart it. If you want to log them to a file you should use the access log command
https://docs.gunicorn.org/en/20.x/settings.html#accesslog
To enable debugging at a log level, you should specify it using the log level command.
https://docs.gunicorn.org/en/20.x/settings.html#accesslog

You also have the option to override this, if you wish to use uvicorn directly instead.
https://learn.microsoft.com/en-us/azure/developer/python/configure-python-web-app-on-app-service#other-frameworks-and-web-servers

[supplemarty]

Sorry if I am missing something but why does the uvicorn logger work for the enrichment app but not the backend web app?

[KronemeyerJoshua]

Is there a specific error or statement you are not seeing that you can point to?
The backend makes use of asynchronous generators, which means logging when it happens must be proceeded by a yield statement to actually output to the log if it's inside an asynchronous generator.

I also noticed the compare and directGPT approaches do not have a logging config set, which may be a reason if it is specific to logging those approaches as a global logging level is not specified with logging.basicConfig

Logging is set at several different layers of the application, narrowing it down to a specific file or function would be helpful in debugging this.

[supplemarty]

In the backend app.py you will see the log = logging.getLogger("uvicorn") as I pointed out above. The code was written to setLevel("DEBUG"). Any calls to log.debug("HELLO WORLD") fail to show any output in the log stream for the backend web app nor app insights. I used the out of the box deployment code.

[dayland]

We have added this to the backlog and assigned an engineer to review.