OTLP/HTTP does not use OTEL_EXPORTER_OTLP_ENDPOINT as a base URL correctly.

[TylerHelmuth]

Bug Report

Symptom

OTEL_EXPORTER_OTLP_ENDPOINT is not being treated as a base url in the OTLP HTTP exporter as per the OTLP/HTTP spec. Instead, the signal endpoint is being appended only if it is not already present. Method in question is AppendPathIfNotPresent.

What is the expected behavior?

No matter what OTEL_EXPORTER_OTLP_ENDPOINT is, the signal endpoint should be appended using slashes appropriately. For example, if OTEL_EXPORTER_OTLP_ENDPOINT is http://localhost:4318/v1/traces/, then the resulting url should be http://localhost:4318/v1/traces/v1/traces for traces.

What is the actual behavior?

The signal endpoint is only appended if it is not already present. For example, if OTEL_EXPORTER_OTLP_ENDPOINT is http://localhost:4318/v1/traces/ the signal endpoint is not appended.

Reproduce

Set OTEL_EXPORTER_OTLP_ENDPOINT to be http://localhost:4318/v1/traces/. Observer that traces are send to http://localhost:4318/v1/traces instead of http://localhost:4318/v1/traces/v1/traces.

Additional Context

I realize this is a pretty silly issue. Maybe the spec needs updated? Definitely open that discussion.

[kedare]

+1 on this, this is quite critical, it's the only implementation I found that doesn't respect this specification.

[MeijerM1]

Is there any update on this? It seems like quite a big issue that the OTLP exporter is simply not respecting the spec when using OTLP/HTTP.

[cijothomas]

https://github.com/open-telemetry/opentelemetry-dotnet/issues/5054 maybe same/duplicate!