Make built-in MDC key `req.id` give `requestId` of root `ServiceRequestContext`

Currently, MDC key, req.id, evaluates to requestId of ClientRequestContext even if it has ServiceRequestContext as its root. This undermines the benefit of using MDC as the logs within ClientRequestContext don’t leave any contextual information of which service request they are scoped to.

I wonder if this is an intended behavior and I should introduce a custom MDC key to trace client logs within a span of service request.

If not, a simple fix for BuiltInProperty.REQ_ID will do the work:

// AS-IS
REQ_ID("req.id", log -> log.context().id().text())

// TO-BE
REQ_ID("req.id", log -> log.context().root() != null ? log.context().root().id().text()
                                                     : log.context().id().text())

[trustin]

req.rootOrSelfId ? 😆

[ks-yim]

Just make sure that req.root_id returns null if ClientRequestContext.root() returns null. Is that right?

Right, I will work in that way!