Not working for multiple workers by uvicorn

[maveius]

Describe the bug
Did anyone tried to use it for multiple workers >1 like 4 ?
uvicorn app.main:app --host 0.0.0.0 --port 8001 --workers 4
When multiple workers by uvicorn I think that different sub-processes are inside and session is not shared between workers (processes) then issue like detail
"AADSTS501481: The Code_Verifier does not match the code_challenge supplied in the authorization request. Trace ID:..."

To Reproduce
Steps to reproduce the behavior:

1. Run in docker by uvicorn app with workers 4 uvicorn app.main:app --host 0.0.0.0 --port 8001 --workers 4
2. Click on login button
3. Wait for result
4. See error "AADSTS501481: The Code_Verifier does not match the code_challenge supplied in the authorization request. Trace ID:..."

Expected behavior
It should not depend on which worker has this code in memory in one single session, but should share between processes.

Environment Settings

• OS: Linux / Docker (python:3.12)
• Python Version: 3.12
• Package Versions:
• msal: 1.32.3
• fastapi: 0.115.13
• fastapi_msal: 2.1.7

Additional context

[dudil]

@maveius - this is correct, but for this there should be a support for a file based / external session management like redis.
Was on my roadmap but didn't got there.
If required we can look into that together.

[maciejmochol]

@dudil is there a good reason why it cannot be implemented stateless? if it can be we're happy to look into it with you :)

[tjadevries]

I would like to have this resolved as well. @dudil , @maveius , I propose to use diskcache (https://pypi.org/project/diskcache/) for this: performant and no dependency on an external server. Would that be a good option for you as well?