otelgin: update error handling to set attributes instead of recording errors

Fixes open-telemetry#8441

This change updates the error handling in otelgin middleware to follow
the instrumentation guidelines established in open-telemetry#8386:

- Replace span.RecordError() calls with span.SetAttributes(ErrorType())
- Set error.type attribute for the first error when c.Errors is not empty
- Multiple errors are still captured in the status description via c.Errors.String()
- Update tests to verify error.type attribute instead of span events

This provides better consistency across OpenTelemetry instrumentation
packages and follows the semantic conventions for error handling.

Author: Eshaan-byte

instrumentation/github.com/gin-gonic/gin/otelgin/gin.go

@@ -15,6 +15,7 @@ import (
 	"go.opentelemetry.io/otel/codes"
 	"go.opentelemetry.io/otel/metric"
 	"go.opentelemetry.io/otel/propagation"
+	otelsemconv "go.opentelemetry.io/otel/semconv/v1.37.0"
 	oteltrace "go.opentelemetry.io/otel/trace"
 
 	"go.opentelemetry.io/contrib/instrumentation/github.com/gin-gonic/gin/otelgin/internal/semconv"
@@ -120,9 +121,9 @@ func Middleware(service string, opts ...Option) gin.HandlerFunc {
 
 		if len(c.Errors) > 0 {
 			span.SetStatus(codes.Error, c.Errors.String())
-			for _, err := range c.Errors {
-				span.RecordError(err.Err)
-			}
+			// Set error.type attribute for the first error
+			// Multiple errors are already captured in the status description via c.Errors.String()
+			span.SetAttributes(otelsemconv.ErrorType(c.Errors[0].Err))
 		}
 
 		// Record the server-side attributes.

instrumentation/github.com/gin-gonic/gin/otelgin/gin_test.go

@@ -27,6 +27,7 @@ import (
 	"go.opentelemetry.io/otel/sdk/metric/metricdata/metricdatatest"
 	sdktrace "go.opentelemetry.io/otel/sdk/trace"
 	"go.opentelemetry.io/otel/sdk/trace/tracetest"
+	semconv "go.opentelemetry.io/otel/semconv/v1.37.0"
 	"go.opentelemetry.io/otel/trace"
 	"go.opentelemetry.io/otel/trace/noop"
 
@@ -202,15 +203,9 @@ func TestError(t *testing.T) {
 	assert.Contains(t, attr, attribute.String("server.address", "foobar"))
 	assert.Contains(t, attr, attribute.Int("http.response.status_code", http.StatusInternalServerError))
 
-	// verify the error events
-	events := span.Events()
-	require.Len(t, events, 2)
-	assert.Equal(t, "exception", events[0].Name)
-	assert.Contains(t, events[0].Attributes, attribute.String("exception.type", "*errors.errorString"))
-	assert.Contains(t, events[0].Attributes, attribute.String("exception.message", "oh no one"))
-	assert.Equal(t, "exception", events[1].Name)
-	assert.Contains(t, events[1].Attributes, attribute.String("exception.type", "*errors.errorString"))
-	assert.Contains(t, events[1].Attributes, attribute.String("exception.message", "oh no two"))
+	// verify the error.type attribute is set (using first error)
+	firstErr := errors.New("oh no one")
+	assert.Contains(t, attr, semconv.ErrorType(firstErr))
 
 	// server errors set the status
 	assert.Equal(t, codes.Error, span.Status().Code)
@@ -261,8 +256,9 @@ func TestSpanStatus(t *testing.T) {
 
 		require.Len(t, sr.Ended(), 1)
 		assert.Equal(t, codes.Error, sr.Ended()[0].Status().Code)
-		require.Len(t, sr.Ended()[0].Events(), 1)
-		assert.Contains(t, sr.Ended()[0].Events()[0].Attributes, attribute.String("exception.message", "something went wrong"))
+		// verify the error.type attribute is set
+		err := errors.New("something went wrong")
+		assert.Contains(t, sr.Ended()[0].Attributes(), semconv.ErrorType(err))
 	})
 }