Crate krabka_trace_context 

W3C Trace Context propagation shared by Krabka’s wire-protocol crates.

This crate is the single place where a trace context crosses a Krabka process boundary. It covers the three shapes those boundaries take:

• Kafka record headers: current_trace_headers injects the traceparent and tracestate pair that travels with a record. extract_context and set_remote_parent rebuild that pair.
• Structured RPC payloads: TraceCarrier is a serde-serialisable field inside an existing request envelope, so a node-to-node call needs no extra frame.
• SQL text: extract_sqlcommenter reads the sqlcommenter /*traceparent='…'*/ comment that OpenTelemetry-instrumented database drivers already append.

This crate deliberately depends on nothing but opentelemetry, tracing, tracing-opentelemetry, and serde. The OTLP exporter, its configuration, and the process-wide subscriber live in krabka-telemetry. That crate is unpublished, and it pulls in a web server, a CLI parser, and a profiler. None of those belong in a crate that a protocol codec links against. krabka-telemetry re-exports this crate as krabka_telemetry::propagation.

This crate validates ingress from an untrusted client. See TraceCarrier::from_w3c for the exact rules, and for the reason it never keeps the raw client string.

Structs

SqlCommenterTrace

A trace context read out of a sqlcommenter tag, borrowed from the statement.

TraceCarrier

A W3C trace context in transit, sized to fit in a request payload.

Enums

TraceContextError

Why Krabka rejected a client-supplied W3C trace context.

Constants

TRACEPARENT

The canonical W3C trace-context header keys.

TRACESTATE

Functions

current_trace_headers

The W3C trace-context headers for the current tracing span.

extract_context

Rebuild an OpenTelemetry Context from Kafka record headers.

extract_sqlcommenter

Extract a sqlcommenter trace context from sql, if it carries one.

set_remote_parent

Make span a child of the trace that headers carries.