[Route Groups] Implement IApplicationBuilder to support grouped middleware

[halter73]

We want MapGroup to support middleware via the IApplicationBuilder interface so things like UseResponseCompression(), UseHttpLogging(), UseForwardedHeaders(), UseRequestLocalization(), terminal middleware like UseStaticFiles() and more can be called on a group.

Describe the solution you'd like

This still needs design, but there are a lot of open questions. We still need to figure out how we define a middleware that runs every time a route handler in a given group is hit. before running the endpoint and similar middleware from inner groups?

• How do we deal with middleware that checks the request path?
  • Can we trim the group prefix from the path?
• What about middleware that's aware of grouping and wants the real full path?
  • Do we add a new feature to support this?
  • Can middleware use default endpoint metadata (#41429) to infer the real full path?
• What if no endpoint is matched, but the middleware would have been terminal?
  • Do we create a low-priority catchall endpoint with the route prefix?
• Then what if the middleware isn't terminal?
  • Can we still fallback to the normal missing endpoint logic if we add a fake catchall endpoint?
• Will we support middleware rewriting the route after matching a specific group prefix and rerun routing?
  • This seems like too much. What if the new

[ghost]

Thanks for contacting us.

We're moving this issue to the .NET 7 Planning milestone for future evaluation / consideration. We would like to keep this around to collect more feedback, which can help us with prioritizing this work. We will re-evaluate this issue, during our next planning meeting(s). If we later determine, that the issue has no community involvement, or it's very rare and low-impact issue, we will close it - so that the team can focus on more important and high impact issues. To learn more about what to expect next and how this issue will be handled you can read more about our triage process here.