Set Schema URL when exporting traces to OTLP

We previously were recording the Schema URL but were not setting
the recorded value when exporting. This change now uses the recorded
value when exporting to OTLP.

CHANGELOG.md

@@ -8,6 +8,10 @@ This project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.htm
 
 ## [Unreleased]
 
+### Added
+
+- OTLP trace exporter now sets the SchemaURL field in the exported telemetry if the Tracer has WithSchemaURL option. (#2242)
+
 ### Changed
 
 - NoopMeterProvider is now private and NewNoopMeterProvider must be used to obtain a noopMeterProvider. (#2237)

exporters/otlp/otlptrace/internal/tracetransform/span.go

@@ -60,6 +60,7 @@ func Spans(sdl []tracesdk.ReadOnlySpan) []*tracepb.ResourceSpans {
 			ils = &tracepb.InstrumentationLibrarySpans{
 				InstrumentationLibrary: InstrumentationLibrary(sd.InstrumentationLibrary()),
 				Spans:                  []*tracepb.Span{},
+				SchemaUrl:              sd.InstrumentationLibrary().SchemaURL,
 			}
 		}
 		ils.Spans = append(ils.Spans, span(sd))
@@ -72,6 +73,7 @@ func Spans(sdl []tracesdk.ReadOnlySpan) []*tracepb.ResourceSpans {
 			rs = &tracepb.ResourceSpans{
 				Resource:                    Resource(sd.Resource()),
 				InstrumentationLibrarySpans: []*tracepb.InstrumentationLibrarySpans{ils},
+				SchemaUrl:                   sd.Resource().SchemaURL(),
 			}
 			rsm[rKey] = rs
 			continue

exporters/otlp/otlptrace/internal/tracetransform/span_test.go

@@ -25,14 +25,14 @@ import (
 	"google.golang.org/protobuf/proto"
 
 	"go.opentelemetry.io/otel/attribute"
-	"go.opentelemetry.io/otel/trace"
-	tracepb "go.opentelemetry.io/proto/otlp/trace/v1"
-
 	"go.opentelemetry.io/otel/codes"
 	"go.opentelemetry.io/otel/sdk/instrumentation"
 	"go.opentelemetry.io/otel/sdk/resource"
 	tracesdk "go.opentelemetry.io/otel/sdk/trace"
 	"go.opentelemetry.io/otel/sdk/trace/tracetest"
+	semconv "go.opentelemetry.io/otel/semconv/v1.4.0"
+	"go.opentelemetry.io/otel/trace"
+	tracepb "go.opentelemetry.io/proto/otlp/trace/v1"
 )
 
 func TestSpanKind(t *testing.T) {
@@ -266,10 +266,16 @@ func TestSpanData(t *testing.T) {
 		DroppedAttributes: 1,
 		DroppedEvents:     2,
 		DroppedLinks:      3,
-		Resource:          resource.NewSchemaless(attribute.String("rk1", "rv1"), attribute.Int64("rk2", 5), attribute.StringSlice("rk3", []string{"sv1", "sv2"})),
+		Resource: resource.NewWithAttributes(
+			"http://example.com/custom-resource-schema",
+			attribute.String("rk1", "rv1"),
+			attribute.Int64("rk2", 5),
+			attribute.StringSlice("rk3", []string{"sv1", "sv2"}),
+		),
 		InstrumentationLibrary: instrumentation.Library{
-			Name:    "go.opentelemetry.io/test/otel",
-			Version: "v0.0.1",
+			Name:      "go.opentelemetry.io/test/otel",
+			Version:   "v0.0.1",
+			SchemaURL: semconv.SchemaURL,
 		},
 	}
 
@@ -298,8 +304,10 @@ func TestSpanData(t *testing.T) {
 	require.Len(t, got, 1)
 
 	assert.Equal(t, got[0].GetResource(), Resource(spanData.Resource))
+	assert.Equal(t, got[0].SchemaUrl, spanData.Resource.SchemaURL())
 	ilSpans := got[0].GetInstrumentationLibrarySpans()
 	require.Len(t, ilSpans, 1)
+	assert.Equal(t, ilSpans[0].SchemaUrl, spanData.InstrumentationLibrary.SchemaURL)
 	assert.Equal(t, ilSpans[0].GetInstrumentationLibrary(), InstrumentationLibrary(spanData.InstrumentationLibrary))
 	require.Len(t, ilSpans[0].Spans, 1)
 	actualSpan := ilSpans[0].Spans[0]