[otelhttp] transport metrics

[RangelReale]

Add HTTP client metrics following the semantic conventions.

As users of Transport are not expected to have a handler where they can customize the attributes using a Labeler, callback function options were added to add attributes from the request and the reponse objects.

Fixes #3134 Fixes #1336

[codecov[bot]]

Codecov Report

Merging #3769 (45ceb1d) into main (7d9626d) will increase coverage by 0.0%. Report is 1 commits behind head on main. The diff coverage is 94.4%.

:exclamation: Current head 45ceb1d differs from pull request most recent head e28520c. Consider uploading reports for the commit e28520c to get more accurate results

Additional details and impacted files

@@          Coverage Diff          @@
##            main   #3769   +/-   ##
=====================================
  Coverage   79.4%   79.4%           
=====================================
  Files        166     166           
  Lines      10360   10401   +41     
=====================================
+ Hits        8230    8266   +36     
- Misses      1996    1999    +3     
- Partials     134     136    +2     

Files Changed	Coverage Δ
instrumentation/net/http/otelhttp/common.go	100.0% <ø> (ø)
instrumentation/net/http/otelhttp/transport.go	94.1% <93.4%> (-0.7%)	:arrow_down:
instrumentation/net/http/otelhttp/config.go	84.6% <100.0%> (+1.7%)	:arrow_up:
instrumentation/net/http/otelhttp/handler.go	86.9% <100.0%> (ø)
instrumentation/net/http/otelhttp/wrap.go	92.5% <100.0%> (+7.4%)	:arrow_up:

... and 3 files with indirect coverage changes

[dmathieu]

This would need a changelog, and tests.

[RangelReale]

This would need a changelog, and tests.

Add tests and changelog.

[RangelReale]

Hmm CI shows a data race message that I can't reproduce locally.

[pellared]

Hmm CI shows a data race message that I can't reproduce locally.

For reference: https://github.com/open-telemetry/opentelemetry-go-contrib/actions/runs/4883405160/jobs/8714784942

Have you tried running multiple times? E.g. by calling go test -race -count=1000 ?

EDIT: ~~At first glance it looks not related to your changes. If I am correct, then it would be better to create a separate issue for it.~~

EDIT 2: The data race is in your code. https://github.com/open-telemetry/opentelemetry-go-contrib/pull/3769#discussion_r1187378315. PS. I managed to get the data race on my machine (but the probability to hit it is extremely low. I had to run go test -race -count=10000 multiple times in instrumentation/net/http/otelhttp/test directory).

[pellared]

@RangelReale are you still willing to work on this?

[RangelReale]

yes, I''m available either to follow up or if someone wants to takeover also fine.

[pellared]

yes, I''m available either to follow up or if someone wants to takeover also fine.

It is fine if you follow up. I will do my best to take look in the beginning of next week.

[pellared]

@Aneurysm9, can you please review this PR (as module codeowner)?

[jlordiales]

Curious if this is currently blocked by anything? Would be awesome to have this merged and released when possible

[Sovietaced]

@RangelReale What is the latest on this? Do you need any help?

[RangelReale]

@RangelReale What is the latest on this? Do you need any help?

@Sovietaced I've not been following too much the latest changes, if you want to help/assume this fork, it is fine with me.

[Sovietaced]

@Sovietaced I've not been following too much the latest changes, if you want to help/assume this fork, it is fine with me.

Thanks! I have made a fork and will be going through the code tomorrow. I will open up another pull request once I deeply understand the code and have addressed any outstanding comments here.

[Sovietaced]

I have an initial draft of this work continued here: https://github.com/open-telemetry/opentelemetry-go-contrib/pull/4707

Would appreciate any reviews