Fix Weighted Invalid Backend Logic

internal/xds/translator/route.go

@@ -244,39 +244,33 @@
 			Weight: &wrapperspb.UInt32Value{Value: backendWeights.Invalid},
 		}
 		weightedClusters = append(weightedClusters, invalidCluster)
-		return &routev3.RouteAction{
-			// Intentionally route to a non-existent cluster and return a 500 error when it is not found
-			ClusterNotFoundResponseCode: routev3.RouteAction_INTERNAL_SERVER_ERROR,
-			ClusterSpecifier: &routev3.RouteAction_WeightedClusters{
-				WeightedClusters: &routev3.WeightedCluster{
-					Clusters: weightedClusters,
-				},
-			},
-		}
 	}
 
 	for _, destinationSetting := range settings {
-		if destinationSetting.Filters != nil {
+		if len(destinationSetting.Endpoints) > 0 {
 			validCluster := &routev3.WeightedCluster_ClusterWeight{
 				Name:   backendWeights.Name,
 				Weight: &wrapperspb.UInt32Value{Value: *destinationSetting.Weight},
 			}
 
-			if len(destinationSetting.Filters.AddRequestHeaders) > 0 {
-				validCluster.RequestHeadersToAdd = append(validCluster.RequestHeadersToAdd, buildXdsAddedHeaders(destinationSetting.Filters.AddRequestHeaders)...)
-			}
+			if destinationSetting.Filters != nil {
+				if len(destinationSetting.Filters.AddRequestHeaders) > 0 {
+					validCluster.RequestHeadersToAdd = append(validCluster.RequestHeadersToAdd, buildXdsAddedHeaders(destinationSetting.Filters.AddRequestHeaders)...)
+				}
 
-			if len(destinationSetting.Filters.RemoveRequestHeaders) > 0 {
-				validCluster.RequestHeadersToRemove = append(validCluster.RequestHeadersToRemove, destinationSetting.Filters.RemoveRequestHeaders...)
-			}
+				if len(destinationSetting.Filters.RemoveRequestHeaders) > 0 {
+					validCluster.RequestHeadersToRemove = append(validCluster.RequestHeadersToRemove, destinationSetting.Filters.RemoveRequestHeaders...)
+				}
 
-			if len(destinationSetting.Filters.AddResponseHeaders) > 0 {
-				validCluster.ResponseHeadersToAdd = append(validCluster.ResponseHeadersToAdd, buildXdsAddedHeaders(destinationSetting.Filters.AddResponseHeaders)...)
-			}
+				if len(destinationSetting.Filters.AddResponseHeaders) > 0 {
+					validCluster.ResponseHeadersToAdd = append(validCluster.ResponseHeadersToAdd, buildXdsAddedHeaders(destinationSetting.Filters.AddResponseHeaders)...)
+				}
 
-			if len(destinationSetting.Filters.RemoveResponseHeaders) > 0 {
-				validCluster.ResponseHeadersToRemove = append(validCluster.ResponseHeadersToRemove, destinationSetting.Filters.RemoveResponseHeaders...)
+				if len(destinationSetting.Filters.RemoveResponseHeaders) > 0 {
+					validCluster.ResponseHeadersToRemove = append(validCluster.ResponseHeadersToRemove, destinationSetting.Filters.RemoveResponseHeaders...)
+				}
 			}
+
 			weightedClusters = append(weightedClusters, validCluster)
 		}
 	}

internal/xds/translator/testdata/out/xds-ir/http-route-weighted-invalid-backend.routes.yaml

@@ -16,3 +16,5 @@
           clusters:
           - name: invalid-backend-cluster
             weight: 1
+          - name: first-route-dest
+            weight: 1

release-notes/current.yaml

@@ -23,6 +23,7 @@ bug fixes: |
   Fixed reference grant from EnvoyExtensionPolicy to referenced ext-proc backend not respected
   Fixed BackendTrafficPolicy not applying to Gateway Route when Route has a Request Timeout defined
   Fixed proxies connected to the secondary EG were not receiving xDS configuration
+  Fixed traffic splitting when some backends were invalid
 
 # Enhancements that improve performance.
 performance improvements: |