Premise

Django middlewares sometimes can override request.urlconf for the current request which it has a contract for using subsequently as the source of truth for url related operations.

As a result, we also need to respect the overwritten urlconf in our transaction name resolving.

Solution

I finally went with an _after_get_response solution. The resolution is repeated code but runs only if urlconf is overwritten. I wanted to touch as little of existing logic as possible.

For reference, I went back and forth several times between doing it in a couple of other places.

• _before_get_response - this doesn't work because it runs before all the django middlewares
• middleware wrapping - this feels clunky since the new code block would run on every middleware invocation

Problem

One of our customers have a django-tenants multi-tenant setup. They have a dynamically resolved urlconf and set ROOT_URLCONF to an empty string which breaks this get_resolver in Django.

This results in a silent exception when we try to update the transaction name and hence they see Generic WSGI request for all their requests.

References

• https://docs.djangoproject.com/en/4.0/topics/http/urls/#how-django-processes-a-request
• https://docs.djangoproject.com/en/4.0/topics/http/middleware/
• https://getsentry.atlassian.net/browse/WEB-530