feat: store OTEL process context in named anonymous mapping on Linux

ddtrace/tracer/otelprocesscontext.go

@@ -0,0 +1,27 @@
+// Unless explicitly stated otherwise all files in this repository are licensed
+// under the Apache License Version 2.0.
+// This product includes software developed at Datadog (https://www.datadoghq.com/).
+// Copyright 2025 Datadog, Inc.
+package tracer
+
+// OtelProcessContext represents the OTEL context for the process.
+//
+//go:generate go run github.com/tinylib/msgp -unexported -marshal=true -o=otelprocesscontext_msgp.go -tests=false
+type otelProcessContext struct {
+	// https://opentelemetry.io/docs/specs/semconv/registry/attributes/deployment/#deployment-environment-name
+	DeploymentEnvironmentName string `msg:"deployment.environment.name"`
+	// https://opentelemetry.io/docs/specs/semconv/registry/attributes/host/#host-name
+	HostName string `msg:"host.name"`
+	// https://opentelemetry.io/docs/specs/semconv/registry/attributes/service/#service-instance-id
+	ServiceInstanceID string `msg:"service.instance.id"`
+	// https://opentelemetry.io/docs/specs/semconv/registry/attributes/service/#service-name
+	ServiceName string `msg:"service.name"`
+	// https://opentelemetry.io/docs/specs/semconv/registry/attributes/service/#service-version
+	ServiceVersion string `msg:"service.version"`
+	// https://opentelemetry.io/docs/specs/semconv/registry/attributes/telemetry/#telemetry-sdk-language
+	TelemetrySDKLanguage string `msg:"telemetry.sdk.language"`
+	// https://opentelemetry.io/docs/specs/semconv/registry/attributes/telemetry/#telemetry-sdk-version
+	TelemetrySDKVersion string `msg:"telemetry.sdk.version"`
+	// https://opentelemetry.io/docs/specs/semconv/registry/attributes/telemetry/#telemetry-sdk-name
+	TelemetrySdkName string `msg:"telemetry.sdk.name"`
+}

ddtrace/tracer/tracer.go

@@ -277,15 +277,20 @@ func Start(opts ...StartOption) error {
 	// DD_INSTRUMENTATION_TELEMETRY_ENABLED env var
 	t.telemetry = startTelemetry(t.config)
 
-	// store the configuration in an in-memory file, allowing it to be read to
-	// determine if the process is instrumented with a tracer and to retrive
-	// relevant tracing information.
+	// store the configuration in an in-memory file and in a named anonymous mapping,
+	// allowing it to be read to determine if the process is instrumented with a tracer
+	// and to retrieve relevant tracing information.
 	storeConfig(t.config)
 
 	globalinternal.SetTracerInitialized(true)
 	return nil
 }
 
+// storeConfig stores the process level tracing context both in an in-memory file and
+// in a named anonymous mapping.
+// This allows an external process, such as the Datadog Agent or fullhost profiler,
+// to determine if the process is instrumented with a tracer and to retrieve the process
+// level tracing context.
 func storeConfig(c *config) {
 	uuid, _ := uuid.NewRandom()
 	name := fmt.Sprintf("datadog-tracer-info-%s", uuid.String()[0:8])
@@ -308,6 +313,23 @@ func storeConfig(c *config) {
 	if err != nil {
 		log.Error("failed to store the configuration: %s", err.Error())
 	}
+
+	processContext := otelProcessContext{
+		DeploymentEnvironmentName: c.env,
+		HostName:                  c.hostname,
+		ServiceInstanceID:         globalconfig.RuntimeID(),
+		ServiceName:               c.serviceName,
+		ServiceVersion:            c.version,
+		TelemetrySDKLanguage:      "go",
+		TelemetrySDKVersion:       version.Tag,
+		TelemetrySdkName:          "dd-trace-go",
+	}
+
+	data, _ = processContext.MarshalMsg(nil)
+	err = globalinternal.CreateOtelProcessContextMapping(data)
+	if err != nil {
+		log.Error("failed to store the OTEL process context: %s", err.Error())
+	}
 }
 
 // Stop stops the started tracer. Subsequent calls are valid but become no-op.

internal/otelcontextmapping.go

@@ -0,0 +1,12 @@
+// Unless explicitly stated otherwise all files in this repository are licensed
+// under the Apache License Version 2.0.
+// This product includes software developed at Datadog (https://www.datadoghq.com/).
+// Copyright 2025 Datadog, Inc.
+
+//go:build !linux
+
+package internal
+
+func CreateOtelProcessContextMapping(data []byte) error {
+	return nil
+}