Function build_tracer_layer 

pub fn build_tracer_layer<S>(
    config: &OtelTracingConfig,
) -> Result<(OpenTelemetryLayer<S, Tracer>, SdkTracerProvider), OtelTracingError>
where
    S: Subscriber + for<'a> LookupSpan<'a>,

Available on crate feature otel-tracing only.

Build an OTel tracer + tracing-subscriber layer ready for composition.

Sets the resulting SdkTracerProvider as the global tracer provider (so crate::transport::propagation picks it up). The returned layer should be added to a tracing_subscriber::Registry.

The provider is also returned so callers can .shutdown() it on graceful exit (otherwise the batch exporter loses queued spans).

Errors

Returns OtelTracingError::ExporterBuild if the OTLP exporter cannot be initialised (typically endpoint format / TLS setup issues).