Support Distributed Tracing

[philkra]

Provide support for distributed tracing, in case an http request with the header TRACEPARENT or ELASTIC-APM-TRACEPARENT is issued, use the value that must comply W3C trace context, example.

• Implement
• Documentation (including on how manually pass tracing context)

[science695]

Not sure if this should be in its own issue, but is there a possibility of also adding the header to the intercepted curl / guzzle outgoing requests? (In addition to handling when traceparent is in the incoming request headers)

I know the RUM / js agent has a config for allowing certain domains to have the header added.