Add a header propagation middleware and message handler

We should consider providing an in-the-box solution for propagating headers from the current request to an outgoing http request.

This would consist of a middleware that can be configured to stamp certain headers on a feature of the current request. Then a message handler uses IHttpContextAccessor to grab the feature and apply the headers to outgoing requests.

Maybe similar to: https://github.com/stevejgordon/CorrelationId/tree/dev/src/CorrelationId from @stevejgordon or (sample @davidfowl made)

Also consider using Activity

[davidfowl]

Here’s the sample I wrote https://gist.github.com/davidfowl/c34633f1ddc519f030a1c0c5abe8e867. This is just generic header propagation not tied to any specific implementation of activities or id generation etc.

[alefranz]

I’ve aslo published an unofficial backport to AspNetCore 2.1 and 2.2. https://www.nuget.org/packages/HeaderPropagation/

I’ll update it now with the latest changes.