Fix default URL for OTLP Trace/Metrics for http/protobuf

[pjanotti]

Changes

Setting only the protocol to http/protobuf wasn't enough to get the OTLP exporters, trace and metrics, sending to the correct endpoint. Setting the env var or the property directly works, but, it should just work by setting the protocol.

[codecov]

Codecov Report

Merging #3098 (b1b6997) into main (d3c0c6e) will decrease coverage by 0.09%.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##             main    #3098      +/-   ##
==========================================
- Coverage   84.74%   84.64%   -0.10%     
==========================================
  Files         259      259              
  Lines        9236     9228       -8     
==========================================
- Hits         7827     7811      -16     
- Misses       1409     1417       +8     

Impacted Files	Coverage Δ
...orter.OpenTelemetryProtocol/OtlpExporterOptions.cs	100.00% <ø> (ø)
...TelemetryProtocol/OtlpExporterOptionsExtensions.cs	97.67% <ø> (-0.13%)	⬇️
...nTelemetryProtocol/OtlpMetricExporterExtensions.cs	67.85% <ø> (-1.11%)	⬇️
...metryProtocol/OtlpTraceExporterHelperExtensions.cs	90.47% <ø> (-0.44%)	⬇️
...mentation/ExportClient/BaseOtlpHttpExportClient.cs	100.00% <100.00%> (ø)
...tation/ExportClient/OtlpHttpMetricsExportClient.cs	62.50% <100.00%> (-4.17%)	⬇️
...entation/ExportClient/OtlpHttpTraceExportClient.cs	87.50% <100.00%> (-2.98%)	⬇️
...xporter.OpenTelemetryProtocol/OtlpTraceExporter.cs	36.36% <0.00%> (-22.73%)	⬇️
...entation/ExportClient/OtlpGrpcTraceExportClient.cs	35.71% <0.00%> (-14.29%)	⬇️
...mentation/ExportClient/BaseOtlpGrpcExportClient.cs	50.00% <0.00%> (-11.12%)	⬇️

[pjanotti]

🤔 the tests passed locally, need to look...

ah, incorrect assumption of my part: I thought that these tests were running against the localhost and my setup used that, likely I need a better place to test this.

[pjanotti]

I had a conversation with @pellared and will be updating the PR: I will be trying to remove the extension method that already does some checks regarding the path for the exporters.

[cijothomas]

@pjanotti one conflict came another PR merge.. could you resolve that please?

[pjanotti]

Done @cijothomas

[alanwest]

LGTM. Just a question about config precedence not really related specifically to this PR.

[pjanotti]

Thanks for the review @alanwest

@cijothomas @CodeBlanch ptal @ #3098 (comment)

[cijothomas]

@pjanotti As as follow up, would you help modifying the examples to show how to use the http option?
For example: I think the collector needs to enable http support 1st...
https://github.com/open-telemetry/opentelemetry-dotnet/blob/main/examples/Console/otlp-collector-example/config.yaml

Anything else?

[pjanotti]

Sure thing @cijothomas - I will run the examples locally and create a PR if needed. IIRC the OTLP receiver on the collector receives both grpc and http by default, but, as I said I will double-check if the examples are looking good for OTLP.