OpenTelemetry span names for URLs are shortened

[adinauer]

Integration

sentry-opentelemetry-agent

Java Version

any

Version

8

Steps to Reproduce

Have an endpoint like /person/extra/long/path and send a request in.

Expected Result

A meaningful transaction name.

Actual Result

The transaction name is shortened to GET /**.

We are using the http.route span attribute which contains above value.

[lcian]

When the URL has a corresponding route, then the http.route is populated with the correct value.
When there is no corresponding route/mapping for a specific URL, then http.route will contain GET /**.

In our SpanDescriptionExtractor we prioritize http.route.
Perhaps we could detect if http.route contains a * (or for stricter matching, if it matches exactly /**) and use url.path instead.
This is not perfect because the server might be mapped only to a specific path (not necessarily the apex) and with url.path we would report the whole path in the URL.

On a related note, this happens also in Servlet instrumentation, where http.route contains the path that the servlet is mapped to. See this recent issue about it open-telemetry/opentelemetry-java-instrumentation#13802.

In my opinion, this behavior of setting http.route to e.g. GET /** for servlets is not conforming to the OTEL spec, because it says "MUST NOT be populated when this is not supported by the HTTP server framework".

[lcian]

If we consider the cardinality concern valid, then we should keep it as GET /**
If, instead, we think it's more valuable to have GET <full url> despite cardinality issues, then we could prioritize url.path when we detect that the url has been shortened.

[lcian]

Closing this issue as not planned because:

• we currently set the span name to {method} {http.route} which is in accordance to the OTEL convention
• the only usecase I can think of for having the full URL as the span name is to perform filtering/aggregation based on that value, in which case it's possible to filter/aggregate on the url.path attribute instead