Class MediatorTraceProviderBuilderExtensions

Namespace

Trellis.Mediator

Assembly

Trellis.Mediator.dll

Extension methods for configuring OpenTelemetry tracing for the Trellis mediator pipeline.

public static class MediatorTraceProviderBuilderExtensions

Inheritance

object

MediatorTraceProviderBuilderExtensions

Inherited Members

object.Equals(object)

object.Equals(object, object)

object.GetHashCode()

object.GetType()

object.MemberwiseClone()

object.ReferenceEquals(object, object)

object.ToString()

Methods

AddTrellisMediatorInstrumentation(TracerProviderBuilder)

Adds Trellis mediator pipeline instrumentation to the OpenTelemetry tracer provider, so the per-command and per-query span opened by TracingBehavior<TMessage, TResponse> is collected.

public static TracerProviderBuilder AddTrellisMediatorInstrumentation(this TracerProviderBuilder builder)

Parameters

builder TracerProviderBuilder

The OpenTelemetry.Trace.TracerProviderBuilder to configure.

Returns

TracerProviderBuilder

The same OpenTelemetry.Trace.TracerProviderBuilder instance for method chaining.

Examples

services.AddOpenTelemetry()
    .WithTracing(tracing => tracing
        .AddAspNetCoreInstrumentation()
        .AddTrellisMediatorInstrumentation()
        .AddOtlpExporter());

Remarks

AddTrellisBehaviors() registers TracingBehavior<TMessage, TResponse>, so every command and query already *calls* StartActivity. That call only produces a live activity if a listener is subscribed to the source, so without this registration StartActivity returns null and the handler span is never collected.

Why this matters more than a missing span. The absence is indistinguishable from success: a service with no handler spans looks exactly like a service in which nothing failed. The failure tags this span carries — error.code and error.type, the same values the HTTP response body reports — are the ones an operator reaches for when asking which rule rejected a request, so the configuration gap is discovered during an incident rather than before one.

The registered source is ActivitySourceName ("Trellis.Mediator"). Consumers may equivalently call AddSource("Trellis.Mediator"); this helper exists so the name does not have to be repeated as a string literal, matching AddTrellisResultsInstrumentation() in Trellis.Core and AddTrellisPrimitivesInstrumentation() in Trellis.Primitives. The method is named for the Trellis pipeline specifically because it instruments Trellis behaviors rather than the underlying Mediator library.

This is the pipeline-behavior altitude that the Trellis.Core tracing guidance recommends for high-throughput services, in preference to per-Result-operator spans: one span per request carrying the business message name and the failure code.