[FSSDK-9705] feat: add OpenTelemetry tracing

pkg/middleware/trace.go

@@ -21,15 +21,43 @@ import (
 	"net/http"
 
 	"go.opentelemetry.io/otel"
+	semconv "go.opentelemetry.io/otel/semconv/v1.4.0"
 )
 
+type statusRecorder struct {
+	http.ResponseWriter
+	statusCode int
+}
+
+func (r *statusRecorder) WriteHeader(code int) {
+	r.statusCode = code
+	r.ResponseWriter.WriteHeader(code)
+}
+
 func AddTracing(tracerName, spanName string) func(http.Handler) http.Handler {
 	return func(next http.Handler) http.Handler {
 		fn := func(w http.ResponseWriter, r *http.Request) {
 			ctx, span := otel.Tracer(tracerName).Start(r.Context(), spanName)
 			defer span.End()
 
-			next.ServeHTTP(w, r.WithContext(ctx))
+			span.SetAttributes(
+				semconv.HTTPMethodKey.String(r.Method),
+				semconv.HTTPRouteKey.String(r.URL.Path),
+				semconv.HTTPURLKey.String(r.URL.String()),
+				semconv.HTTPHostKey.String(r.Host),
+				semconv.HTTPSchemeKey.String(r.URL.Scheme),
+			)
+
+			rec := &statusRecorder{
+				ResponseWriter: w,
+				statusCode:     http.StatusOK,
+			}
+
+			next.ServeHTTP(rec, r.WithContext(ctx))
+
+			span.SetAttributes(
+				semconv.HTTPStatusCodeKey.Int(rec.statusCode),
+			)
 		}
 		return http.HandlerFunc(fn)
 	}

pkg/optimizely/client.go

@@ -151,6 +151,9 @@ func (c *OptlyClient) SetForcedVariation(ctx context.Context, experimentKey, use
 		override.Messages = messages
 	}
 
+	span.SetAttributes(attribute.String("variationKey", override.VariationKey))
+	span.SetAttributes(attribute.String("experimentKey", override.ExperimentKey))
+
 	c.ForcedVariations.SetVariation(forcedVariationKey, variationKey)
 	return &override, nil
 }
@@ -186,6 +189,9 @@ func (c *OptlyClient) RemoveForcedVariation(ctx context.Context, experimentKey,
 	override.Messages = messages
 	c.ForcedVariations.RemoveVariation(forcedVariationKey)
 
+	span.SetAttributes(attribute.String("variationKey", override.VariationKey))
+	span.SetAttributes(attribute.String("experimentKey", override.ExperimentKey))
+
 	return &override, nil
 }
 
@@ -210,6 +216,12 @@ func (c *OptlyClient) ActivateFeature(ctx context.Context, key string, uc entiti
 		VariationKey:  unsafeDecisionInfo.VariationKey,
 	}
 
+	span.SetAttributes(attribute.String("variationKey", dec.VariationKey))
+	span.SetAttributes(attribute.String("experimentKey", dec.ExperimentKey))
+	span.SetAttributes(attribute.String("featureKey", dec.FeatureKey))
+	span.SetAttributes(attribute.Bool("enabled", dec.Enabled))
+	span.SetAttributes(attribute.String("type", dec.Type))
+
 	return dec, nil
 }
 
@@ -239,5 +251,10 @@ func (c *OptlyClient) ActivateExperiment(ctx context.Context, key string, uc ent
 		Variables:     map[string]interface{}{},
 	}
 
+	span.SetAttributes(attribute.String("variationKey", dec.VariationKey))
+	span.SetAttributes(attribute.String("experimentKey", dec.ExperimentKey))
+	span.SetAttributes(attribute.Bool("enabled", dec.Enabled))
+	span.SetAttributes(attribute.String("type", dec.Type))
+
 	return dec, nil
 }