Disable x-b3-flags propagation

[cello86]

Hi,
we configured the opentracing plugin on nginx 1.19.8 and all works fine, but we noticed that all requests had the header X-B3-Flags set to 0 and our backend API GW logged an error if this header has a value different from "1".

We tried to use proxy_set_header config to override this value but it's not possible to remove the header sent by nginx.

Is is possible to avoid the forward of the "x-b3-flags: 0" and omit it if necessary via config file?

Thanks,
Marcello

[miry]

@cello86 Is it not part of the tracer: zippkin? I think it should be fixed in https://github.com/rnburn/zipkin-cpp-opentracing/blob/a134d5bb073392a0e2fe23c5fe5ef145c2ceb7ea/zipkin/src/zipkin_core_constants.h#L34

[miry]

According the documentation https://github.com/openzipkin/b3-propagation#debug-flag this flag should be 1 (for debug), or any other value. I think need to request help of API GW to have other values for this header.

[cello86]

@miry we noticed that is a part of the zipkin-cpp-opentracing module and it forwards all requests with the x-b3-flags to zero, but on nginx side you can't override it to 0 or 1 in case of debug.

Thanks,
Marcello