snapshot of https://github.com/grpc/grpc-go.git (master, 2026-09-15; blobs > 131072B omitted)

interop/xds/custom_lb_test.go

@@ -0,0 +1,135 @@
+/*
+ *
+ * Copyright 2023 gRPC authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ *
+ */
+
+package xds
+
+import (
+	"context"
+	"errors"
+	"fmt"
+	"testing"
+	"time"
+
+	"google.golang.org/grpc"
+	"google.golang.org/grpc/credentials/insecure"
+	"google.golang.org/grpc/internal"
+	"google.golang.org/grpc/internal/grpctest"
+	"google.golang.org/grpc/internal/stubserver"
+	"google.golang.org/grpc/internal/testutils"
+	testgrpc "google.golang.org/grpc/interop/grpc_testing"
+	testpb "google.golang.org/grpc/interop/grpc_testing"
+	"google.golang.org/grpc/metadata"
+	"google.golang.org/grpc/resolver"
+	"google.golang.org/grpc/resolver/manual"
+	"google.golang.org/grpc/serviceconfig"
+)
+
+var defaultTestTimeout = 5 * time.Second
+
+type s struct {
+	grpctest.Tester
+}
+
+func Test(t *testing.T) {
+	grpctest.RunSubTests(t, s{})
+}
+
+// TestCustomLB tests the Custom LB for the interop client. It configures the
+// custom lb as the top level Load Balancing policy of the channel, then asserts
+// it can successfully make an RPC and also that the rpc behavior the Custom LB
+// is configured with makes it's way to the server in metadata.
+func (s) TestCustomLB(t *testing.T) {
+	errCh := testutils.NewChannel()
+	// Setup a backend which verifies the expected rpc-behavior metadata is
+	// present in the request.
+	backend := &stubserver.StubServer{
+		UnaryCallF: func(ctx context.Context, _ *testpb.SimpleRequest) (*testpb.SimpleResponse, error) {
+			md, ok := metadata.FromIncomingContext(ctx)
+			if !ok {
+				errCh.Send(errors.New("failed to receive metadata"))
+				return &testpb.SimpleResponse{}, nil
+			}
+			rpcBMD := md.Get("rpc-behavior")
+			if len(rpcBMD) != 1 {
+				errCh.Send(fmt.Errorf("received %d values for metadata key \"rpc-behavior\", want 1", len(rpcBMD)))
+				return &testpb.SimpleResponse{}, nil
+			}
+			wantVal := "error-code-0"
+			if rpcBMD[0] != wantVal {
+				errCh.Send(fmt.Errorf("metadata val for key \"rpc-behavior\": got val %v, want val %v", rpcBMD[0], wantVal))
+				return &testpb.SimpleResponse{}, nil
+			}
+			// Success.
+			errCh.Send(nil)
+			return &testpb.SimpleResponse{}, nil
+		},
+	}
+	if err := backend.StartServer(); err != nil {
+		t.Fatalf("Failed to start backend: %v", err)
+	}
+	t.Logf("Started good TestService backend at: %q", backend.Address)
+	defer backend.Stop()
+
+	lbCfgJSON := `{
+  		"loadBalancingConfig": [
+    		{
+      			"test.RpcBehaviorLoadBalancer": {
+					"rpcBehavior": "error-code-0"
+      		}
+    	}
+  	]
+	}`
+
+	sc := internal.ParseServiceConfig.(func(string) *serviceconfig.ParseResult)(lbCfgJSON)
+	mr := manual.NewBuilderWithScheme("customlb-e2e")
+	defer mr.Close()
+	mr.InitialState(resolver.State{
+		Addresses: []resolver.Address{
+			{Addr: backend.Address},
+		},
+		ServiceConfig: sc,
+	})
+
+	cc, err := grpc.NewClient(mr.Scheme()+":///", grpc.WithResolvers(mr), grpc.WithTransportCredentials(insecure.NewCredentials()))
+	if err != nil {
+		t.Fatalf("grpc.NewClient() failed: %v", err)
+	}
+	defer cc.Close()
+	ctx, cancel := context.WithTimeout(context.Background(), defaultTestTimeout)
+	defer cancel()
+	testServiceClient := testgrpc.NewTestServiceClient(cc)
+
+	// Make a Unary RPC. This RPC should be successful due to the round_robin
+	// leaf balancer. Also, the custom load balancer should inject the
+	// "rpc-behavior" string it is configured with into the metadata sent to
+	// server.
+	if _, err := testServiceClient.UnaryCall(ctx, &testpb.SimpleRequest{}); err != nil {
+		t.Fatalf("EmptyCall() failed: %v", err)
+	}
+
+	val, err := errCh.Receive(ctx)
+	if err != nil {
+		t.Fatalf("error receiving from errCh: %v", err)
+	}
+
+	// Should receive nil on the error channel which implies backend verified it
+	// correctly received the correct "rpc-behavior" metadata.
+	if err, ok := val.(error); ok {
+		t.Fatalf("error in backend verifications on metadata received: %v", err)
+	}
+}