Question: url.scheme with reverse proxy?

[dmathieu]

I'm looking at the http span doc, and while it does explain the expected behavior regarding reverse proxies, it only mentions it for the server. namespace.

My question therefore is: what about other attributes that may be different between the external request and the internal one when a reverse proxy is involved, such as url.scheme.
The scheme may be https outside the proxy, and http within the internal network.

In which case, should we try to detect the external scheme and use that rather than the internal value?

[trask]

hi @dmathieu, thanks for pointing out this miss! the intention was for url.scheme to follow the same pattern as server.address and server.port when it comes to reverse proxies. you can see the Java instrumentation behavior reflects this:

• https://github.com/open-telemetry/opentelemetry-java-instrumentation/blob/553fbb30c2509a4bdef25a9e5d1bb310fadc7900/instrumentation-api/src/main/java/io/opentelemetry/instrumentation/api/semconv/url/internal/InternalUrlAttributesExtractor.java#L41-L45
• https://github.com/open-telemetry/opentelemetry-java-instrumentation/blob/553fbb30c2509a4bdef25a9e5d1bb310fadc7900/instrumentation-api/src/main/java/io/opentelemetry/instrumentation/api/semconv/http/ForwardedUrlSchemeProvider.java#L22-L38