provide a way to opt-in for url.template attribute for http.client.request.duration metric

[codrutpanea]

Is your feature request related to a problem? Please describe.

We need the url.template attribute for http.client.request.duration metrics and java-instrumentation is not generating that attribute.

Describe the solution you'd like

The attribute is declared as Opt-In in the docs here https://opentelemetry.io/docs/specs/semconv/http/http-metrics/#http-client but there is no way to opt in when using opentelemetry-java-instrumentation

Describe alternatives you've considered

No response

Additional context

No response

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[trask]

hi @codrutpanea, I don't think there's any Java HTTP client instrumentation that captures url.template even on spans yet.

[trask]

related: #10506

[Munken]

I had a look at the code and it seems the interface is defined, but not implemented.

I also had a look at the apache http client and RestTemplate instrumentation, and it seems the current AttributeGetter attaches to low in the call stack i.e. after the url have been templated.

[laurit]

provide a way to opt-in for url.template attribute for http.client.request.duration metric

you can opt-in to attributes using metrics views, see https://github.com/open-telemetry/opentelemetry-java/tree/main/sdk-extensions/incubator#view-file-configuration We could also consider adding url.template to metrics with a flag, perhaps we could reuse otel.instrumentation.http.client.emit-experimental-telemetry for that.

Since what you are asking is technically already implemented I'd suggest you to rework your question, and perhaps close this issue and open a new one, to ask what you really need. There aren't many http clients that have a concept of template. For spring RestTemplate I believe we could use the user supplied value as template. For other http clients it might be possible to match user provided uri with user provided regular expressions to deduce the template.

[Munken]

@laurit I think the question is fair.

Currently it is gated via OTEL_INSTRUMENTATION_HTTP_CLIENT_EMIT_EXPERIMENTAL_TELEMETRY see this PR.

This is not clear from the documentation.

Beyond that, there currently exist no implementation that provides url.template.

[laurit]

@laurit I think the question is fair.

sure the question is fair, but I get the feeling that what @codrutpanea really needs is for a specific http client instrumentation to produce the url.template attribute. In my opinion creating an issue for that would increase the chances for that getting implemented. As stated above url.template could be added to the metric with metric view if there was an instrumentation that actually produced that attribute.

[codrutpanea]

if i understand this correctly I can actually opt-in for the url.template attribute by using the env var OTEL_INSTRUMENTATION_HTTP_CLIENT_EMIT_EXPERIMENTAL_TELEMETRY, but the attribute is not populated because the the http client that I use org.springframework.web.client.RestTemplate is not generating that attribute

[Munken]

@codrutpanea correct. I have an open draft pr but that only adds the url template to the WebClient and RestClient.

Considering that RestTemplate is in maintenance mode I would suggest switching

[trask]

#14612 provides url.template for Spring 6 RestTemplate