Trace Context - Ferron 3 (alpha) documentation

Trace Context

Ferron 3 supports W3C Trace Context (traceparent and tracestate) propagation and generation. This enables end-to-end observability by carrying trace identifiers across service boundaries.

Incoming traceparent and tracestate headers are parsed and used as the parent for the internal ferron.request span. If missing, a new trace context can be generated (default behavior). These identifiers are then propagated to upstream services when using the reverse proxy modules.

Trace configuration

These directives are configured within the http block.

Directive	Arguments	Description	Default
`trace`	none	Opens a block for trace-related configuration.	-
`generate`	boolean	Specifies whether a new trace context should be generated if the incoming request lacks one.	`true`
`sampled`	boolean	Specifies the default sampling flag for generated trace contexts.	`false`

Configuration example:

example.com
    http {
        trace {
            generate true
            sampled true
        }
    }
}

Notes and troubleshooting

The http-proxy and http-fproxy modules automatically propagate the current trace context to upstream services.
Generating and propagating trace headers carries unique identifiers. Ensure this complies with your privacy requirements.
Ferron 3 preserves the incoming tracestate header and propagates it as-is.
To export these traces to an external system, configure an observability sink such as observability-otlp.