Fix per-signal endpoint parsing in OTLP exporters

[MrAlias]

Resolve #2338

[codecov]

Codecov Report

Merging #2433 (6977091) into main (b177541) will increase coverage by 0.0%.
The diff coverage is 94.4%.

@@          Coverage Diff          @@
##            main   #2433   +/-   ##
=====================================
  Coverage   76.0%   76.0%           
=====================================
  Files        173     173           
  Lines      11938   12008   +70     
=====================================
+ Hits        9074    9134   +60     
- Misses      2621    2629    +8     
- Partials     243     245    +2     

Impacted Files	Coverage Δ
...s/otlp/otlpmetric/internal/otlpconfig/envconfig.go	94.8% <94.2%> (+1.7%)	⬆️
...rs/otlp/otlptrace/internal/otlpconfig/envconfig.go	94.8% <94.2%> (-1.2%)	⬇️
exporters/otlp/otlpmetric/otlpmetrichttp/client.go	78.7% <100.0%> (ø)
exporters/otlp/otlptrace/otlptracehttp/client.go	83.3% <100.0%> (ø)
sdk/metric/refcount_mapped.go	80.0% <0.0%> (-20.0%)	⬇️
sdk/metric/sdk.go	80.0% <0.0%> (-1.5%)	⬇️

[pellared]

I think it could be good to update the docs e.g. here: https://github.com/open-telemetry/opentelemetry-go/tree/main/exporters/otlp/otlptrace

Can be done in a separate PR.

[MrAlias]

I think it could be good to update the docs e.g. here: https://github.com/open-telemetry/opentelemetry-go/tree/main/exporters/otlp/otlptrace

The linked documentation does not contain any mention of the behavior that is being fixed here as far as I can see. I'm not sure what needs to be updated there.

[pellared]

I think it could be good to update the docs e.g. here: https://github.com/open-telemetry/opentelemetry-go/tree/main/exporters/otlp/otlptrace

The linked documentation does not contain any mention of the behavior that is being fixed here as far as I can see. I'm not sure what needs to be updated there.

I find it very inconvenient that there is no information that OTEL_EXPORTER_OTLP_ENDPOINT and OTEL_EXPORTER_OTLP_TRACES_ENDPOINT work differently. It suggests that all the configurations are equivalent. I suggest at least giving a reference to https://github.com/open-telemetry/opentelemetry-specification/blob/main/specification/protocol/exporter.md#endpoint-urls-for-otlphttp or whole https://github.com/open-telemetry/opentelemetry-specification/blob/main/specification/protocol/exporter.md

[MrAlias]

I find it very inconvenient that there is no information that OTEL_EXPORTER_OTLP_ENDPOINT and OTEL_EXPORTER_OTLP_TRACES_ENDPOINT work differently. It suggests that all the configurations are equivalent. I suggest at least giving a reference to https://github.com/open-telemetry/opentelemetry-specification/blob/main/specification/protocol/exporter.md#endpoint-urls-for-otlphttp or whole https://github.com/open-telemetry/opentelemetry-specification/blob/main/specification/protocol/exporter.md

Ah, I see. Let me look into adding something.