ExtractInbound returns existing tracker or does lazy creation of new one to be used.

Middleware reports last Kedge proxy error on each HTTP request (if spotted) by incrementing metrics and producing log line.

ReqWrappedWithTracker returns copy of HTTP request with tracker in context.

SetKedgeErrorHeaders adds Kedge Error headers useful to immediately see kedge error on HTTP response.

SetWinchErrorHeaders adds winch Error headers useful to immediately see winch error on HTTP response.

Tracker is used to report an error spotted by kedge itself (error that happen when request was not succesfully proxied because of some reason).