Support query params for traces url

[nozik]

Our OpenTelemetry collector is deployed behind an API gateway that we don't control. IThe API gateway requires passing a certain query parameter - which can't be moved to a header (and certainly not to the OTLP request body). For that reason, we need the http exporter to support adding query parameters.

[pellared]

Can you please add a description? Why do you want such functionality? Are other SDKs supporting this? It is not common to have query parameters in POST HTTP requests.

Take notice that the OpenTelemetry Specification does not require supporting query parameters. See: https://github.com/open-telemetry/opentelemetry-specification/blob/main/specification/protocol/exporter.md.

Some time ago it was even saying that it MUST NOT support it: open-telemetry/opentelemetry-specification#3739

[nozik]

@pellared Added a description. From my experience query parameters are quite common in POST APIs (perhaps not a best practice), and I see no harm in adding them.

[codecov]

Codecov Report

Attention: Patch coverage is 50.00000% with 9 lines in your changes are missing coverage. Please review.

Project coverage is 83.6%. Comparing base (5449f08) to head (9f44031).
Report is 5 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##            main   #5152     +/-   ##
=======================================
- Coverage   83.8%   83.6%   -0.2%     
=======================================
  Files        248     252      +4     
  Lines      16345   16443     +98     
=======================================
+ Hits       13709   13759     +50     
- Misses      2347    2394     +47     
- Partials     289     290      +1     

Files	Coverage Δ
...trace/otlptracehttp/internal/otlpconfig/options.go	92.4% <100.0%> (+0.2%)	⬆️
exporters/otlp/otlptrace/otlptracegrpc/options.go	73.5% <0.0%> (-2.9%)	⬇️
exporters/otlp/otlptrace/otlptracehttp/client.go	78.7% <66.6%> (-0.6%)	⬇️
...trace/otlptracegrpc/internal/otlpconfig/options.go	90.4% <0.0%> (-3.3%)	⬇️

... and 6 files with indirect coverage changes

[pellared]

Our OpenTelemetry collector is deployed behind an API gateway that we don't control. The API gateway requires passing a certain query parameter - which can't be moved to a header.

I do not support such change unless it is clearly specified in https://github.com/open-telemetry/opentelemetry-specification/blob/main/specification/protocol/exporter.md that the implementation SHOULD honor the query URL component.

Personally, I am against such proposal. Therefore, please try to address it yourself in the https://github.com/open-telemetry/opentelemetry-specification. I guess it would be still better (and maybe even easier) to change the API gateway.

For now, I am closing the PR. We can reopen it later if needed.