bugfix labels to append to parent context instead of ignoring

eager_router.go

@@ -78,7 +78,7 @@ func (fanIn *eagerRouterFanIn) Aggregate(
 			routes []Component
 
 			// response labels
-			labels Labels = NewLabelsMap()
+			labels Labels
 
 			// index of current primary route
 			currentRouteIdx int
@@ -88,6 +88,13 @@ func (fanIn *eagerRouterFanIn) Aggregate(
 			masterResponse Response
 		)
 
+		labelMap, ok := ctx.Value(CtxComponentLabelsKey).(Labels)
+		if ok {
+			labels = labelMap
+		} else {
+			labels = NewLabelsMap()
+		}
+
 		for masterResponse == nil {
 			select {
 			case resp, ok := <-responseCh:
@@ -98,7 +105,11 @@ func (fanIn *eagerRouterFanIn) Aggregate(
 				}
 			case routesOrderResponse, ok := <-routesOrderCh:
 				if ok {
-					labels = routesOrderResponse.Labels
+					//Overwrite parent labels with strategy labels
+					for _, key := range routesOrderResponse.Labels.Keys() {
+						labels.WithLabel(key, routesOrderResponse.Labels.Label(key)...)
+					}
+
 					if routesOrderResponse.Err != nil {
 						masterResponse = NewErrorResponse(errors.NewFiberError(req.Protocol(), routesOrderResponse.Err))
 					} else {

labels_test.go

@@ -1,10 +1,15 @@
 package fiber_test
 
 import (
+	"context"
 	"sort"
+	"strings"
 	"testing"
 
 	"github.com/gojek/fiber"
+	"github.com/gojek/fiber/extras"
+	"github.com/gojek/fiber/internal/testutils"
+	testUtilsHttp "github.com/gojek/fiber/internal/testutils/http"
 	"github.com/stretchr/testify/assert"
 )
 
@@ -89,3 +94,84 @@ func TestLabelsMapLabel(t *testing.T) {
 		})
 	}
 }
+
+// This test uses RandomRoutingStrategy which will always append context of idx
+// Labels should be preserved for fiber.CtxComponentLabelsKey context key
+func Test_Router_Dispatch_Labels(t *testing.T) {
+	lazyRouter := fiber.NewLazyRouter("lazy-router")
+	lazyRouter.SetStrategy(new(extras.RandomRoutingStrategy))
+
+	eagerRouter := fiber.NewEagerRouter("eager-router")
+	eagerRouter.SetStrategy(new(extras.RandomRoutingStrategy))
+
+	testRouters := []fiber.MultiRouteComponent{eagerRouter, lazyRouter}
+
+	tests := []struct {
+		name               string
+		initialLabelKey    any
+		initialLabelValue  any
+		expectedLabelKey   string
+		expectedLabelValue string
+		router             []fiber.MultiRouteComponent
+	}{
+		{
+			name:               "new label",
+			expectedLabelKey:   "idx",
+			expectedLabelValue: "0",
+			router:             testRouters,
+		},
+		{
+			name:               "overwritten label",
+			initialLabelKey:    "idx",
+			initialLabelValue:  "111",
+			expectedLabelKey:   "idx",
+			expectedLabelValue: "0",
+			router:             testRouters,
+		},
+		{
+			name:               "existing label not preserved, wrong key",
+			initialLabelKey:    "t",
+			initialLabelValue:  "11",
+			expectedLabelKey:   "t",
+			expectedLabelValue: "",
+			router:             testRouters,
+		},
+		{
+			name:               "existing label preserved",
+			initialLabelKey:    fiber.CtxComponentLabelsKey,
+			initialLabelValue:  fiber.NewLabelsMap().WithLabel("t", "11"),
+			expectedLabelKey:   "t",
+			expectedLabelValue: "11",
+			router:             testRouters,
+		},
+		{
+			name:               "existing label not preserved, unexpected value type",
+			initialLabelKey:    fiber.CtxComponentLabelsKey,
+			initialLabelValue:  map[string]string{"t": "11"},
+			expectedLabelKey:   "t",
+			expectedLabelValue: "",
+			router:             testRouters,
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			for _, router := range tt.router {
+				router.SetRoutes(map[string]fiber.Component{
+					"route-a": testutils.NewMockComponent(
+						"route-a",
+						testUtilsHttp.DelayedResponse{Response: testUtilsHttp.MockResp(200, "A-OK", nil, nil)}),
+				})
+				ctx := context.Background()
+				if tt.initialLabelKey != nil {
+					ctx = context.WithValue(ctx, tt.initialLabelKey, tt.initialLabelValue)
+				}
+				request := testUtilsHttp.MockReq("POST", "http://localhost:8080/router", "payload")
+				resp, ok := <-router.Dispatch(ctx, request).Iter()
+				assert.True(t, ok)
+				label := strings.Join(resp.Label(tt.expectedLabelKey), ",")
+				assert.Equal(t, tt.expectedLabelValue, label)
+			}
+		})
+	}
+}

lazy_router.go

@@ -2,7 +2,6 @@ package fiber
 
 import (
 	"context"
-
 	"github.com/gojek/fiber/errors"
 	"github.com/gojek/fiber/util"
 )
@@ -50,14 +49,25 @@ func (r *LazyRouter) Dispatch(ctx context.Context, req Request) ResponseQueue {
 		defer close(out)
 
 		var routes []Component
-		var labels Labels = NewLabelsMap()
+		var labels Labels
+
+		labelMap, ok := ctx.Value(CtxComponentLabelsKey).(Labels)
+		if ok {
+			labels = labelMap
+		} else {
+			labels = NewLabelsMap()
+		}
 
 		routesOrderCh := r.strategy.getRoutesOrder(ctx, req, r.routes)
 
 		select {
 		case routesOrderResponse, ok := <-routesOrderCh:
 			if ok {
-				labels = routesOrderResponse.Labels
+				//Overwrite parent labels with strategy labels
+				for _, key := range routesOrderResponse.Labels.Keys() {
+					labels.WithLabel(key, routesOrderResponse.Labels.Label(key)...)
+				}
+
 				if routesOrderResponse.Err != nil {
 					out <- NewErrorResponse(errors.NewFiberError(req.Protocol(), routesOrderResponse.Err)).WithLabels(labels)
 					return