Investigate metrics endpoint behavior when exception middleware runs

[JamesNK]

Is there an existing issue for this?

• I have searched the existing issues

Describe the bug

OTEL folks noticed that the endpoint is cleared when exception middleware runs. See open-telemetry/opentelemetry-dotnet#5134

Investigate whether this impacts ASP.NET Core's use of the endpoint when building tags for metrics.

Expected Behavior

Metrics endpoint route tag is present when exception middleware runs.

Steps To Reproduce

No response

Exceptions (if any)

No response

.NET Version

net8.0

Anything else?

No response

[davidroth]

Thanks, just reported this also in #52766 (duplicate) 👍

Question: Will this be published in an 8.0 release update or do we have to wait for 9.0? (Hoping for the former)

[JamesNK]

The fix will be back ported to 8.0.2 (available approx Feb or March)

[JamesNK]

Your issue here - #52766 - says the counter is muted. What do you mean by that? With the bug here, I would still expect a value to be recorded, but without a http_route value.

[davidroth]

Your issue here - #52766 - says the counter is muted. What do you mean by that? With the bug here, I would still expect a value to be recorded, but without a http_route value.

My fault. I retested it again and the value is indeed recorded, but without the http_route value. So basically as described in this issue.

[JamesNK]

Reopen to track backport to 8.0

[JamesNK]

Added to backport with #52790.