JAX-RS intergation doesn't work well with web servlet filter

[tmszdmsk]

Extracted from: #13 (comment)

Recently when I was working on Opentracing in Dropwizard project I noticed that jaxrs and servlet integrations do not play well together, i.e. jaxrs-integration spans are not children of servlet-integration created spans. Maybe original idea was that you should have only one of them installed but not all endpoints have to be handled by jaxrs so it is beneficial to have both.
My idea would be to modify jaxrs integration in such a way that:

• if there is active span (presumably created by servlet integration), don't extract span information from request headers
• if there is no active span - proceed as it is now.

[pavolloffay]

It makes sense, but why would you like to use filter integration with jax-rs. Could you please list some use cases?

[tmszdmsk]

@pavolloffay
In the company I work, we want to provide common lib that will instrument our Dropwizard services. Not all endpoints are served by Jersey. We want to trace all.

Actually, in context of this issue, it doesn't have to be servlet filter. It should work the same with interceptors instrumenting e.g. specific web servers like Jetty.

[pavolloffay]

I see thanks, that totally makes sense.

Are you fine with having two spans per a request or do you want to disable the creation if there is an active span?

[tmszdmsk]

Sorry for the delay.

Two spans are actually good because JAX-RS can provide more information in tags e.g. resource method, resource path pattern we can later use to search through the collected data.

I pushed some proof of concept to #74.

[tmszdmsk]

PR merged, closing.

[pavolloffay]

I have pushed 0.1.2.

@tmszdmsk thanks

[tmszdmsk]

👍