Rejected requests can create metrics dimension with unmatched path about akka-http-metrics HOT 6 CLOSED

I think I still get this bug. I use v0.6.0 together with akkaHttpVersion 10.1.11 , akkaVersion 2.5.29 and am using pathLabeled. For 200 requests I get the label specified by pathLabeled ("/GET me"), but when the api responds with an 401 unauthorised for the same path I get "/me" instead so the metrics is not counted together.

from akka-http-metrics.

This behavior depends on the rejection cause. Unmatched path is the rejection leading to 404.

Unauthorised (401) should probably be handled the same way, since a good practice is to always return 401 even if the path requested does not exists. This avoids leaking the (non)existence of resources to rogue users.

I'm reopening this to extend the behavior with other rejections.

Good catch @wake42 !

from akka-http-metrics.

As a note: pathLabeled won't be used in case of rejection. (I'll double check this) that would explain the wrong grouping in your case.

from akka-http-metrics.

The api could also respond with 403 forbidden and 500 internal error. I guess all response codes should be caught by this?

from akka-http-metrics.

If the pathLabeled is not used then how do you group endpoints like /user/123, wouldn't that count every individual user as a separate endpoint for error responses?

from akka-http-metrics.

After double checking the code and running some tests for v1.0.0, this is the actual behavior when pathDimension is enabled:

Let's consider the request GET /user/723abce0-9263-4dad-80a6-4eb7002a86da

For server route

pathLabeled("user" / JavaUUID, "user/:user-id") { userId =>
  complete(StatusCodes.NotFound)
}

Path dimension is user/:user-id

For server route

pathLabeled("user" / JavaUUID, "user/:user-id") { userId =>
  reject
}

Path dimension is unhandled

This difference is due to the way akka-http works with rejections.

In the rejection handler, we have no way to know if the path has been fully matched or not. It's then impossible for the metrics framework to process 'labeling' on the request path. To limit the risk of unbounded metrics generation, path dimension is set to unhandled in this case.

There is however an inconsistency in the metrics framework. For server route:

pathLabeled("user" / JavaUUID, "user/:user-id") { userId =>
  failWith(new Exception("ERROR!"))
}

Path dimension is /user/723abce0-9263-4dad-80a6-4eb7002a86da which is unwanted. Must be replaced by unhandled for consistency

from akka-http-metrics.