xdsclient: new Transport interface and LRS stream implementation (#7717)

xds/internal/xdsclient/internal/internal.go

@@ -20,6 +20,9 @@ package internal
 
 // The following vars can be overridden by tests.
 var (
-	// NewADSStream is a function that returns a new ADS stream.
+	// GRPCNewClient returns a new gRPC Client.
+	GRPCNewClient any // func(string, ...grpc.DialOption) (*grpc.ClientConn, error)
+
+	// NewADSStream returns a new ADS stream.
 	NewADSStream any // func(context.Context, *grpc.ClientConn) (v3adsgrpc.AggregatedDiscoveryService_StreamAggregatedResourcesClient, error)
 )

xds/internal/xdsclient/transport/grpctransport/grpctransport.go

@@ -0,0 +1,138 @@
+/*
+ *
+ * Copyright 2024 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 grpctransport provides an implementation of the transport interface
+// using gRPC.
+package grpctransport
+
+import (
+	"context"
+	"fmt"
+	"time"
+
+	"google.golang.org/grpc"
+	"google.golang.org/grpc/keepalive"
+	"google.golang.org/grpc/xds/internal/xdsclient/internal"
+	"google.golang.org/grpc/xds/internal/xdsclient/transport"
+
+	v3adsgrpc "github.com/envoyproxy/go-control-plane/envoy/service/discovery/v3"
+	v3adspb "github.com/envoyproxy/go-control-plane/envoy/service/discovery/v3"
+	v3lrsgrpc "github.com/envoyproxy/go-control-plane/envoy/service/load_stats/v3"
+	v3lrspb "github.com/envoyproxy/go-control-plane/envoy/service/load_stats/v3"
+)
+
+func init() {
+	internal.GRPCNewClient = grpc.NewClient
+	internal.NewADSStream = func(ctx context.Context, cc *grpc.ClientConn) (v3adsgrpc.AggregatedDiscoveryService_StreamAggregatedResourcesClient, error) {
+		return v3adsgrpc.NewAggregatedDiscoveryServiceClient(cc).StreamAggregatedResources(ctx)
+	}
+}
+
+// Builder provides a way to build a gRPC-based transport to an xDS server.
+type Builder struct{}
+
+// Build creates a new gRPC-based transport to an xDS server using the provided
+// options. This involves creating a grpc.ClientConn to the server identified by
+// the server URI in the provided options.
+func (b *Builder) Build(opts transport.BuildOptions) (transport.Interface, error) {
+	if opts.ServerConfig == nil {
+		return nil, fmt.Errorf("ServerConfig field in opts cannot be nil")
+	}
+
+	// NOTE: The bootstrap package ensures that the server_uri and credentials
+	// inside the server config are always populated. If we end up using a
+	// different type in BuildOptions to specify the server configuration, we
+	// must ensure that those fields are not empty before proceeding.
+
+	// Dial the xDS management server with dial options specified by the server
+	// configuration and a static keepalive configuration that is common across
+	// gRPC language implementations.
+	kpCfg := grpc.WithKeepaliveParams(keepalive.ClientParameters{
+		Time:    5 * time.Minute,
+		Timeout: 20 * time.Second,
+	})
+	dopts := append(opts.ServerConfig.DialOptions(), kpCfg)
+	dialer := internal.GRPCNewClient.(func(string, ...grpc.DialOption) (*grpc.ClientConn, error))
+	cc, err := dialer(opts.ServerConfig.ServerURI(), dopts...)
+	if err != nil {
+		// An error from a non-blocking dial indicates something serious.
+		return nil, fmt.Errorf("failed to create a grpc transport to the management server %q: %v", opts.ServerConfig.ServerURI(), err)
+	}
+	cc.Connect()
+
+	return &grpcTransport{cc: cc}, nil
+}
+
+type grpcTransport struct {
+	cc *grpc.ClientConn
+}
+
+func (g *grpcTransport) CreateStreamingCall(ctx context.Context, method string) (transport.StreamingCall, error) {
+	switch method {
+	case v3adsgrpc.AggregatedDiscoveryService_StreamAggregatedResources_FullMethodName:
+		return g.newADSStreamingCall(ctx)
+	case v3lrsgrpc.LoadReportingService_StreamLoadStats_FullMethodName:
+		return g.newLRSStreamingCall(ctx)
+	default:
+		return nil, fmt.Errorf("unsupported method: %v", method)
+	}
+}
+
+func (g *grpcTransport) newADSStreamingCall(ctx context.Context) (transport.StreamingCall, error) {
+	newStream := internal.NewADSStream.(func(context.Context, *grpc.ClientConn) (v3adsgrpc.AggregatedDiscoveryService_StreamAggregatedResourcesClient, error))
+	stream, err := newStream(ctx, g.cc)
+	if err != nil {
+		return nil, fmt.Errorf("failed to create an ADS stream: %v", err)
+	}
+	return &adsStream{stream: stream}, nil
+}
+
+func (g *grpcTransport) newLRSStreamingCall(ctx context.Context) (transport.StreamingCall, error) {
+	stream, err := v3lrsgrpc.NewLoadReportingServiceClient(g.cc).StreamLoadStats(ctx)
+	if err != nil {
+		return nil, fmt.Errorf("failed to create an LRS stream: %v", err)
+	}
+	return &lrsStream{stream: stream}, nil
+}
+
+func (g *grpcTransport) Close() error {
+	return g.cc.Close()
+}
+
+type adsStream struct {
+	stream v3adsgrpc.AggregatedDiscoveryService_StreamAggregatedResourcesClient
+}
+
+func (a *adsStream) Send(msg any) error {
+	return a.stream.Send(msg.(*v3adspb.DiscoveryRequest))
+}
+
+func (a *adsStream) Recv() (any, error) {
+	return a.stream.Recv()
+}
+
+type lrsStream struct {
+	stream v3lrsgrpc.LoadReportingService_StreamLoadStatsClient
+}
+
+func (l *lrsStream) Send(msg any) error {
+	return l.stream.Send(msg.(*v3lrspb.LoadStatsRequest))
+}
+
+func (l *lrsStream) Recv() (any, error) {
+	return l.stream.Recv()
+}

xds/internal/xdsclient/transport/grpctransport/grpctransport_ext_test.go

@@ -0,0 +1,91 @@
+/*
+ *
+ * Copyright 2022 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 grpctransport_test
+
+import (
+	"testing"
+
+	"google.golang.org/grpc"
+	"google.golang.org/grpc/internal/grpctest"
+	internalbootstrap "google.golang.org/grpc/internal/xds/bootstrap"
+	"google.golang.org/grpc/xds/internal/xdsclient/internal"
+	"google.golang.org/grpc/xds/internal/xdsclient/transport"
+	"google.golang.org/grpc/xds/internal/xdsclient/transport/grpctransport"
+)
+
+type s struct {
+	grpctest.Tester
+}
+
+func Test(t *testing.T) {
+	grpctest.RunSubTests(t, s{})
+}
+
+// Tests that the grpctransport.Builder creates a new grpc.ClientConn every time
+// Build() is called.
+func (s) TestBuild_CustomDialer(t *testing.T) {
+	// Override the dialer with a custom one.
+	customDialerCalled := false
+	origDialer := internal.GRPCNewClient
+	internal.GRPCNewClient = func(target string, opts ...grpc.DialOption) (*grpc.ClientConn, error) {
+		customDialerCalled = true
+		return grpc.NewClient(target, opts...)
+	}
+	defer func() { internal.GRPCNewClient = origDialer }()
+
+	serverCfg, err := internalbootstrap.ServerConfigForTesting(internalbootstrap.ServerConfigTestingOptions{URI: "server-address"})
+	if err != nil {
+		t.Fatalf("Failed to create server config for testing: %v", err)
+	}
+
+	// Create a new transport and ensure that the custom dialer was called.
+	opts := transport.BuildOptions{ServerConfig: serverCfg}
+	builder := &grpctransport.Builder{}
+	tr, err := builder.Build(opts)
+	if err != nil {
+		t.Fatalf("Builder.Build(%+v) failed: %v", opts, err)
+	}
+	defer tr.Close()
+
+	if !customDialerCalled {
+		t.Fatalf("Builder.Build(%+v): custom dialer called = false, want true", opts)
+	}
+	customDialerCalled = false
+
+	// Create another transport and ensure that the custom dialer was called.
+	tr, err = builder.Build(opts)
+	if err != nil {
+		t.Fatalf("Builder.Build(%+v) failed: %v", opts, err)
+	}
+	defer tr.Close()
+
+	if !customDialerCalled {
+		t.Fatalf("Builder.Build(%+v): custom dialer called = false, want true", opts)
+	}
+}
+
+// Tests that the grpctransport.Builder fails to build a transport when the
+// provided BuildOptions do not contain a ServerConfig.
+func (s) TestBuild_EmptyServerConfig(t *testing.T) {
+	builder := &grpctransport.Builder{}
+	opts := transport.BuildOptions{}
+	if tr, err := builder.Build(opts); err == nil {
+		tr.Close()
+		t.Fatalf("Builder.Build(%+v) succeeded when expected to fail", opts)
+	}
+}