`url.scheme` tag is emitted as part of `http.client.request.duration` metric that does not match the OTel spec

[vishweshbankwar]

Description

url.scheme is added by default on http.client.request.duration metric from System.Net.Http. However, it is not part of the required/recommended attributes from the spec.

v1.21
https://github.com/open-telemetry/semantic-conventions/blob/v1.21.0/docs/http/http-metrics.md#metric-httpclientduration

Main
https://github.com/open-telemetry/semantic-conventions/blob/main/docs/http/http-metrics.md#metric-httpclientrequestduration

Reproduction Steps

Test on .NET8.0 RC1 using OTel SDK

Configure SDK

Sdk.CreateMeterProviderBuilder()
.AddMeter("System.Net.Http")
.Build()

Expected behavior

url.scheme is not included by default.

Actual behavior

url.scheme tag is added by default on http.client.request.duration metric

Sample output from sdk

Export http.client.request.duration, The duration of outbound HTTP requests., Unit: s, Meter: System.Net.Http
(2023-09-14T18:44:41.6943865Z, 2023-09-14T18:44:48.7866188Z] http.request.method: GET http.response.status_code: 302 network.protocol.version: 1.1 server.address: www.bing.com url.scheme: http Histogram

runtime/src/libraries/System.Net.Http/src/System/Net/Http/Metrics/MetricsHandler.cs

Line 192 in f7a7b2b

tags.Add("url.scheme", requestUri.Scheme);

Regression?

No response

Known Workarounds

No response

Configuration

No response

Other information

No response

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Issue Details

---

Description

url.scheme is added by default on http.client.request.duration metric from System.Net.Http. However, it is not part of the required/recommended attributes from the spec.

v1.21
https://github.com/open-telemetry/semantic-conventions/blob/v1.21.0/docs/http/http-metrics.md#metric-httpclientduration

Main
https://github.com/open-telemetry/semantic-conventions/blob/main/docs/http/http-metrics.md#metric-httpclientrequestduration

Reproduction Steps

Test on .NET8.0 RC1 using OTel SDK

Configure SDK

Sdk.CreateMeterProviderBuilder()
.AddMeter("System.Net.Http")
.Build()

Expected behavior

url.scheme is not included by default.

Actual behavior

url.scheme tag is added by default on http.client.request.duration metric

Sample output from sdk

Export http.client.request.duration, The duration of outbound HTTP requests., Unit: s, Meter: System.Net.Http
(2023-09-14T18:44:41.6943865Z, 2023-09-14T18:44:48.7866188Z] http.request.method: GET http.response.status_code: 302 network.protocol.version: 1.1 server.address: www.bing.com url.scheme: http Histogram

runtime/src/libraries/System.Net.Http/src/System/Net/Http/Metrics/MetricsHandler.cs

Line 192 in f7a7b2b

tags.Add("url.scheme", requestUri.Scheme);

Regression?

No response

Known Workarounds

No response

Configuration

No response

Other information

No response

Author:	vishweshbankwar
Assignees:	-
Labels:	area-System.Net.Http
Milestone:	-

[antonfirsov]

AFAIK the spec does not prohibit emitting additional tags. There is a proposal documentimg all .NET metrics at open-telemetry/semantic-conventions#283 where url.scheme is included as an attribute of http.client.request.duration.

Do you experience any practical disadvantage from including url.scheme @vishweshbankwar?

This issue has been marked needs-author-action and may be missing some important information.

[lmolkova]

Created open-telemetry/semantic-conventions#356 and proposing open-telemetry/semantic-conventions#357 to fix it on the otel side

[vishweshbankwar]

Closing this issue assuming the open-telemetry/semantic-conventions#356 will be merged.