Support for custom headers

[vivasaayi]

I am using B3 header propagation to trace our Micro Services (more than 150 microservices). It is working out of the box. I am pushing the logs to Jaeger and also to ElasticSearch for further analysis.

I have another scenario where I have to propagate an additional header, "x-web-page-id", to all the upstream services.

The rationale behind this is, when loading a web page, it can make multiple AJAX calls. At the moment, each request gets its own trace id. So, I am not able to group them together. If I can pass another header, "x-web-page-id", then I can find all the upstream requests triggered by that web page.

The other use case is, we are planning to use Istio. It requires all the services to propagate its header (x-request-id).

Could you please provide support for custom headers, that can be included along with Trace/Span Ids?

Without this feature, we have to update all the services to propagate these headers, which is sort of rewriting this module for our needs.