xds: add new fields to XDSConfig (#3100)

Fields are added in: https://github.com/grpc/grpc-proto/pull/64

Other changes:
 - Move XDSConfig from internal to balancer
   - Later we will add a separate config for CDS balancer
 - generate service_config.pb.go and test with json generated from proto message

internal/proto/grpc_service_config/example_test.go

@@ -0,0 +1,59 @@
+/*
+ *
+ * Copyright 2019 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.
+ */
+
+//go:generate ./regenerate.sh
+
+package grpc_service_config_test
+
+import (
+	"testing"
+
+	"github.com/golang/protobuf/jsonpb"
+	wrapperspb "github.com/golang/protobuf/ptypes/wrappers"
+	scpb "google.golang.org/grpc/internal/proto/grpc_service_config"
+)
+
+// TestXdsConfigMarshalToJSON is an example to print json format of xds_config.
+func TestXdsConfigMarshalToJSON(t *testing.T) {
+	c := &scpb.XdsConfig{
+		ChildPolicy: []*scpb.LoadBalancingConfig{
+			{Policy: &scpb.LoadBalancingConfig_Grpclb{
+				Grpclb: &scpb.GrpcLbConfig{},
+			}},
+			{Policy: &scpb.LoadBalancingConfig_RoundRobin{
+				RoundRobin: &scpb.RoundRobinConfig{},
+			}},
+		},
+		FallbackPolicy: []*scpb.LoadBalancingConfig{
+			{Policy: &scpb.LoadBalancingConfig_Grpclb{
+				Grpclb: &scpb.GrpcLbConfig{},
+			}},
+			{Policy: &scpb.LoadBalancingConfig_PickFirst{
+				PickFirst: &scpb.PickFirstConfig{},
+			}},
+		},
+		EdsServiceName: "eds.service.name",
+		LrsLoadReportingServerName: &wrapperspb.StringValue{
+			Value: "lrs.server.name",
+		},
+	}
+	j, err := (&jsonpb.Marshaler{}).MarshalToString(c)
+	if err != nil {
+		t.Fatalf("failed to marshal proto to json: %v", err)
+	}
+	t.Logf(j)
+}

internal/proto/grpc_service_config/regenerate.sh

@@ -0,0 +1,35 @@
+#!/bin/bash
+# Copyright 2019 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.
+
+set -eux -o pipefail
+
+TMP=$(mktemp -d)
+
+function finish {
+  rm -rf "$TMP"
+}
+trap finish EXIT
+
+pushd "$TMP"
+mkdir -p grpc/service_config
+curl https://raw.githubusercontent.com/grpc/grpc-proto/master/grpc/service_config/service_config.proto > grpc/service_config/service_config.proto
+mkdir -p google/rpc
+curl https://raw.githubusercontent.com/googleapis/googleapis/master/google/rpc/code.proto > google/rpc/code.proto
+
+protoc --go_out=plugins=grpc,paths=source_relative:. -I. grpc/service_config/*.proto
+popd
+rm -f ./*.pb.go
+cp "$TMP"/grpc/service_config/*.pb.go ./
+

xds/internal/balancer/config.go

@@ -0,0 +1,117 @@
+/*
+ *
+ * Copyright 2019 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 balancer
+
+import (
+	"encoding/json"
+	"fmt"
+
+	"google.golang.org/grpc/balancer"
+	"google.golang.org/grpc/serviceconfig"
+)
+
+// XDSConfig represents the loadBalancingConfig section of the service config
+// for xDS balancers.
+type XDSConfig struct {
+	serviceconfig.LoadBalancingConfig
+	// BalancerName represents the load balancer to use.
+	BalancerName string
+	// ChildPolicy represents the load balancing config for the child
+	// policy.
+	ChildPolicy *loadBalancingConfig
+	// FallBackPolicy represents the load balancing config for the
+	// fallback.
+	FallBackPolicy *loadBalancingConfig
+	// Name to use in EDS query.  If not present, defaults to the server
+	// name from the target URI.
+	EDSServiceName string
+	// LRS server to send load reports to.  If not present, load reporting
+	// will be disabled.  If set to the empty string, load reporting will
+	// be sent to the same server that we obtained CDS data from.
+	LrsLoadReportingServerName string
+}
+
+// xdsConfigJSON is the intermediate unmarshal result of XDSConfig. ChildPolicy
+// and Fallbackspolicy are post-processed, and for each, the first installed
+// policy is kept.
+type xdsConfigJSON struct {
+	BalancerName               string
+	ChildPolicy                []*loadBalancingConfig
+	FallbackPolicy             []*loadBalancingConfig
+	EDSServiceName             string
+	LRSLoadReportingServerName string
+}
+
+// UnmarshalJSON parses the JSON-encoded byte slice in data and stores it in l.
+// When unmarshalling, we iterate through the childPolicy/fallbackPolicy lists
+// and select the first LB policy which has been registered.
+func (l *XDSConfig) UnmarshalJSON(data []byte) error {
+	var configJSON xdsConfigJSON
+	if err := json.Unmarshal(data, &configJSON); err != nil {
+		return err
+	}
+
+	l.BalancerName = configJSON.BalancerName
+	l.EDSServiceName = configJSON.EDSServiceName
+	l.LrsLoadReportingServerName = configJSON.LRSLoadReportingServerName
+
+	for _, lbcfg := range configJSON.ChildPolicy {
+		if balancer.Get(lbcfg.Name) != nil {
+			l.ChildPolicy = lbcfg
+			break
+		}
+	}
+
+	for _, lbcfg := range configJSON.FallbackPolicy {
+		if balancer.Get(lbcfg.Name) != nil {
+			l.FallBackPolicy = lbcfg
+			break
+		}
+	}
+	return nil
+}
+
+// MarshalJSON returns a JSON encoding of l.
+func (l *XDSConfig) MarshalJSON() ([]byte, error) {
+	return nil, fmt.Errorf("XDSConfig.MarshalJSON() is unimplemented")
+}
+
+// loadBalancingConfig represents a single load balancing config,
+// stored in JSON format.
+type loadBalancingConfig struct {
+	Name   string
+	Config json.RawMessage
+}
+
+// MarshalJSON returns a JSON encoding of l.
+func (l *loadBalancingConfig) MarshalJSON() ([]byte, error) {
+	return nil, fmt.Errorf("loadBalancingConfig.MarshalJSON() is unimplemented")
+}
+
+// UnmarshalJSON parses the JSON-encoded byte slice in data and stores it in l.
+func (l *loadBalancingConfig) UnmarshalJSON(data []byte) error {
+	var cfg map[string]json.RawMessage
+	if err := json.Unmarshal(data, &cfg); err != nil {
+		return err
+	}
+	for name, config := range cfg {
+		l.Name = name
+		l.Config = config
+	}
+	return nil
+}

xds/internal/balancer/xds.go

@@ -34,7 +34,6 @@ import (
 	"google.golang.org/grpc/grpclog"
 	"google.golang.org/grpc/resolver"
 	"google.golang.org/grpc/serviceconfig"
-	xdsinternal "google.golang.org/grpc/xds/internal"
 	"google.golang.org/grpc/xds/internal/balancer/edsbalancer"
 	"google.golang.org/grpc/xds/internal/balancer/lrs"
 )
@@ -89,7 +88,7 @@ func (b *xdsBalancerBuilder) Name() string {
 }
 
 func (b *xdsBalancerBuilder) ParseConfig(c json.RawMessage) (serviceconfig.LoadBalancingConfig, error) {
-	var cfg xdsinternal.LBConfig
+	var cfg XDSConfig
 	if err := json.Unmarshal(c, &cfg); err != nil {
 		return nil, fmt.Errorf("unable to unmarshal balancer config %s into xds config", string(c))
 	}
@@ -133,14 +132,14 @@ type xdsBalancer struct {
 	noSubConnAlert  <-chan struct{}
 
 	client           *client    // may change when passed a different service config
-	config           *xdsinternal.LBConfig // may change when passed a different service config
+	config           *XDSConfig // may change when passed a different service config
 	xdsLB            edsBalancerInterface
 	fallbackLB       balancer.Balancer
 	fallbackInitData *resolver.State // may change when HandleResolved address is called
 	loadStore        lrs.Store
 }
 
-func (x *xdsBalancer) startNewXDSClient(u *xdsinternal.LBConfig) {
+func (x *xdsBalancer) startNewXDSClient(u *XDSConfig) {
 	// If the xdsBalancer is in startup stage, then we need to apply the startup timeout for the first
 	// xdsClient to get a response from the traffic director.
 	if x.startup {
@@ -192,7 +191,7 @@ func (x *xdsBalancer) startNewXDSClient(u *xdsinternal.LBConfig) {
 			prevClient.close()
 		}
 	}
-	x.client = newXDSClient(u.BalancerName, x.buildOpts, x.loadStore, newADS, loseContact, exitCleanup)
+	x.client = newXDSClient(u.BalancerName, u.EDSServiceName, x.buildOpts, x.loadStore, newADS, loseContact, exitCleanup)
 	go x.client.run()
 }
 
@@ -239,7 +238,7 @@ func (x *xdsBalancer) handleGRPCUpdate(update interface{}) {
 			}
 		}
 	case *balancer.ClientConnState:
-		cfg, _ := u.BalancerConfig.(*xdsinternal.LBConfig)
+		cfg, _ := u.BalancerConfig.(*XDSConfig)
 		if cfg == nil {
 			// service config parsing failed. should never happen.
 			return
@@ -248,6 +247,11 @@ func (x *xdsBalancer) handleGRPCUpdate(update interface{}) {
 		var fallbackChanged bool
 		// service config has been updated.
 		if !reflect.DeepEqual(cfg, x.config) {
+			// TODO: handle cfg.LrsLoadReportingServerName and remove log.
+			if cfg.LrsLoadReportingServerName != "" {
+				grpclog.Warningf("xds: lrsLoadReportingServerName is not empty, but is not handled")
+			}
+
 			if x.config == nil {
 				// The first time we get config, we just need to start the xdsClient.
 				x.startNewXDSClient(cfg)
@@ -483,16 +487,16 @@ func (x *xdsBalancer) cancelFallbackAndSwitchEDSBalancerIfNecessary() {
 	}
 }
 
-func (x *xdsBalancer) buildFallBackBalancer(c *xdsinternal.LBConfig) {
+func (x *xdsBalancer) buildFallBackBalancer(c *XDSConfig) {
 	if c.FallBackPolicy == nil {
-		x.buildFallBackBalancer(&xdsinternal.LBConfig{
-			FallBackPolicy: &xdsinternal.LoadBalancingConfig{
+		x.buildFallBackBalancer(&XDSConfig{
+			FallBackPolicy: &loadBalancingConfig{
 				Name: "round_robin",
 			},
 		})
 		return
 	}
-	// builder will always be non-nil, since when parse JSON into xdsinternal.LBConfig, we check whether the specified
+	// builder will always be non-nil, since when parse JSON into xdsinternal.XDSConfig, we check whether the specified
 	// balancer is registered or not.
 	builder := balancer.Get(c.FallBackPolicy.Name)
 

xds/internal/balancer/xds_client.go

@@ -213,9 +213,9 @@ func (c *client) adsCallAttempt() (firstRespReceived bool) {
 	}
 }
 
-func newXDSClient(balancerName string, opts balancer.BuildOptions, loadStore lrs.Store, newADS func(context.Context, proto.Message) error, loseContact func(ctx context.Context), exitCleanup func()) *client {
+func newXDSClient(balancerName string, edsServiceName string, opts balancer.BuildOptions, loadStore lrs.Store, newADS func(context.Context, proto.Message) error, loseContact func(ctx context.Context), exitCleanup func()) *client {
 	c := &client{
-		serviceName:      opts.Target.Endpoint,
+		serviceName:      edsServiceName,
 		dialer:           opts.Dialer,
 		channelzParentID: opts.ChannelzParentID,
 		newADS:           newADS,
@@ -225,6 +225,10 @@ func newXDSClient(balancerName string, opts balancer.BuildOptions, loadStore lrs
 		loadStore:        loadStore,
 	}
 
+	if c.serviceName == "" {
+		c.serviceName = opts.Target.Endpoint
+	}
+
 	c.ctx, c.cancel = context.WithCancel(context.Background())
 
 	// It is possible that NewConfig returns a Config object with certain

xds/internal/balancer/xds_client_test.go

@@ -44,6 +44,7 @@ import (
 
 var (
 	testServiceName    = "test/foo"
+	testEDSServiceName = "test/service/eds"
 	testEDSReq         = &xdspb.DiscoveryRequest{
 		TypeUrl:       edsType,
 		ResourceNames: []string{testServiceName},
@@ -177,6 +178,7 @@ func newTestTrafficDirector() *testTrafficDirector {
 }
 
 type testConfig struct {
+	edsServiceName       string
 	expectedRequests     []*xdspb.DiscoveryRequest
 	responsesToSend      []*xdspb.DiscoveryResponse
 	expectedADSResponses []proto.Message
@@ -208,11 +210,22 @@ func setupServer(t *testing.T) (addr string, td *testTrafficDirector, lrss *lrsS
 }
 
 func (s) TestXdsClientResponseHandling(t *testing.T) {
-	for _, test := range []*testConfig{{
+	for _, test := range []*testConfig{
+		{
 			expectedRequests:     []*xdspb.DiscoveryRequest{testEDSReq},
 			responsesToSend:      []*xdspb.DiscoveryResponse{testEDSResp},
 			expectedADSResponses: []proto.Message{testClusterLoadAssignment},
-	}} {
+		},
+		{
+			edsServiceName: testEDSServiceName,
+			expectedRequests: []*xdspb.DiscoveryRequest{{
+				TypeUrl:       edsType,
+				ResourceNames: []string{testEDSServiceName},
+			}},
+			responsesToSend:      []*xdspb.DiscoveryResponse{testEDSResp},
+			expectedADSResponses: []proto.Message{testClusterLoadAssignment},
+		},
+	} {
 		testXdsClientResponseHandling(t, test)
 	}
 }
@@ -225,7 +238,7 @@ func testXdsClientResponseHandling(t *testing.T, test *testConfig) {
 		adsChan <- i
 		return nil
 	}
-	client := newXDSClient(addr, balancer.BuildOptions{Target: resolver.Target{Endpoint: testServiceName}}, nil, newADS, func(context.Context) {}, func() {})
+	client := newXDSClient(addr, test.edsServiceName, balancer.BuildOptions{Target: resolver.Target{Endpoint: testServiceName}}, nil, newADS, func(context.Context) {}, func() {})
 	defer client.close()
 	go client.run()
 
@@ -282,7 +295,7 @@ func testXdsClientLoseContactRemoteClose(t *testing.T, test *testConfig) {
 	loseContactFunc := func(context.Context) {
 		contactChan <- &loseContact{}
 	}
-	client := newXDSClient(addr, balancer.BuildOptions{Target: resolver.Target{Endpoint: testServiceName}}, nil, newADS, loseContactFunc, func() {})
+	client := newXDSClient(addr, test.edsServiceName, balancer.BuildOptions{Target: resolver.Target{Endpoint: testServiceName}}, nil, newADS, loseContactFunc, func() {})
 	defer client.close()
 	go client.run()
 
@@ -316,7 +329,7 @@ func testXdsClientLoseContactADSRelatedErrorOccur(t *testing.T, test *testConfig
 	loseContactFunc := func(context.Context) {
 		contactChan <- &loseContact{}
 	}
-	client := newXDSClient(addr, balancer.BuildOptions{Target: resolver.Target{Endpoint: testServiceName}}, nil, newADS, loseContactFunc, func() {})
+	client := newXDSClient(addr, test.edsServiceName, balancer.BuildOptions{Target: resolver.Target{Endpoint: testServiceName}}, nil, newADS, loseContactFunc, func() {})
 	defer client.close()
 	go client.run()
 
@@ -350,7 +363,7 @@ func (s) TestXdsClientExponentialRetry(t *testing.T) {
 	loseContactFunc := func(context.Context) {
 		contactChan <- &loseContact{}
 	}
-	client := newXDSClient(addr, balancer.BuildOptions{Target: resolver.Target{Endpoint: testServiceName}}, nil, newADS, loseContactFunc, func() {})
+	client := newXDSClient(addr, "", balancer.BuildOptions{Target: resolver.Target{Endpoint: testServiceName}}, nil, newADS, loseContactFunc, func() {})
 	defer client.close()
 	go client.run()
 

xds/internal/balancer/xds_lrs_test.go

@@ -34,7 +34,6 @@ import (
 	"google.golang.org/grpc/codes"
 	"google.golang.org/grpc/resolver"
 	"google.golang.org/grpc/status"
-	xdsinternal "google.golang.org/grpc/xds/internal"
 )
 
 type lrsServer struct {
@@ -105,7 +104,7 @@ func (s) TestXdsLoadReporting(t *testing.T) {
 		Nanos:   intervalNano,
 	}
 
-	cfg := &xdsinternal.LBConfig{
+	cfg := &XDSConfig{
 		BalancerName: addr,
 	}
 	lb.UpdateClientConnState(balancer.ClientConnState{BalancerConfig: cfg})

xds/internal/balancer/xds_test.go

@@ -19,6 +19,7 @@
 package balancer
 
 import (
+	"bytes"
 	"encoding/json"
 	"reflect"
 	"sync"
@@ -26,13 +27,17 @@ import (
 	"time"
 
 	xdspb "github.com/envoyproxy/go-control-plane/envoy/api/v2"
+	"github.com/golang/protobuf/jsonpb"
 	"github.com/golang/protobuf/proto"
+	wrapperspb "github.com/golang/protobuf/ptypes/wrappers"
+	"github.com/google/go-cmp/cmp"
 	"google.golang.org/grpc/balancer"
 	"google.golang.org/grpc/connectivity"
 	"google.golang.org/grpc/internal/grpctest"
 	"google.golang.org/grpc/internal/leakcheck"
+	scpb "google.golang.org/grpc/internal/proto/grpc_service_config"
 	"google.golang.org/grpc/resolver"
-	xdsinternal "google.golang.org/grpc/xds/internal"
+	"google.golang.org/grpc/serviceconfig"
 	"google.golang.org/grpc/xds/internal/balancer/lrs"
 )
 
@@ -61,10 +66,10 @@ const (
 
 var (
 	testBalancerNameFooBar = "foo.bar"
-	testLBConfigFooBar     = &xdsinternal.LBConfig{
+	testLBConfigFooBar     = &XDSConfig{
 		BalancerName:   testBalancerNameFooBar,
-		ChildPolicy:    &xdsinternal.LoadBalancingConfig{Name: fakeBalancerB},
-		FallBackPolicy: &xdsinternal.LoadBalancingConfig{Name: fakeBalancerA},
+		ChildPolicy:    &loadBalancingConfig{Name: fakeBalancerB},
+		FallBackPolicy: &loadBalancingConfig{Name: fakeBalancerA},
 	}
 
 	specialAddrForBalancerA = resolver.Address{Addr: "this.is.balancer.A"}
@@ -174,8 +179,8 @@ type scStateChange struct {
 type fakeEDSBalancer struct {
 	cc                 balancer.ClientConn
 	edsChan            chan *xdspb.ClusterLoadAssignment
-	childPolicy        chan *xdsinternal.LoadBalancingConfig
-	fallbackPolicy     chan *xdsinternal.LoadBalancingConfig
+	childPolicy        chan *loadBalancingConfig
+	fallbackPolicy     chan *loadBalancingConfig
 	subconnStateChange chan *scStateChange
 	loadStore          lrs.Store
 }
@@ -195,7 +200,7 @@ func (f *fakeEDSBalancer) HandleEDSResponse(edsResp *xdspb.ClusterLoadAssignment
 }
 
 func (f *fakeEDSBalancer) HandleChildPolicy(name string, config json.RawMessage) {
-	f.childPolicy <- &xdsinternal.LoadBalancingConfig{
+	f.childPolicy <- &loadBalancingConfig{
 		Name:   name,
 		Config: config,
 	}
@@ -205,8 +210,8 @@ func newFakeEDSBalancer(cc balancer.ClientConn, loadStore lrs.Store) edsBalancer
 	lb := &fakeEDSBalancer{
 		cc:                 cc,
 		edsChan:            make(chan *xdspb.ClusterLoadAssignment, 10),
-		childPolicy:        make(chan *xdsinternal.LoadBalancingConfig, 10),
-		fallbackPolicy:     make(chan *xdsinternal.LoadBalancingConfig, 10),
+		childPolicy:        make(chan *loadBalancingConfig, 10),
+		fallbackPolicy:     make(chan *loadBalancingConfig, 10),
 		subconnStateChange: make(chan *scStateChange, 10),
 		loadStore:          loadStore,
 	}
@@ -328,10 +333,10 @@ func (s) TestXdsBalanceHandleBalancerConfigBalancerNameUpdate(t *testing.T) {
 	for i := 0; i < 2; i++ {
 		addr, td, _, cleanup := setupServer(t)
 		cleanups = append(cleanups, cleanup)
-		workingLBConfig := &xdsinternal.LBConfig{
+		workingLBConfig := &XDSConfig{
 			BalancerName:   addr,
-			ChildPolicy:    &xdsinternal.LoadBalancingConfig{Name: fakeBalancerA},
-			FallBackPolicy: &xdsinternal.LoadBalancingConfig{Name: fakeBalancerA},
+			ChildPolicy:    &loadBalancingConfig{Name: fakeBalancerA},
+			FallBackPolicy: &loadBalancingConfig{Name: fakeBalancerA},
 		}
 		lb.UpdateClientConnState(balancer.ClientConnState{
 			ResolverState:  resolver.State{Addresses: addrs},
@@ -383,31 +388,31 @@ func (s) TestXdsBalanceHandleBalancerConfigChildPolicyUpdate(t *testing.T) {
 		}
 	}()
 	for _, test := range []struct {
-		cfg                 *xdsinternal.LBConfig
+		cfg                 *XDSConfig
 		responseToSend      *xdspb.DiscoveryResponse
-		expectedChildPolicy *xdsinternal.LoadBalancingConfig
+		expectedChildPolicy *loadBalancingConfig
 	}{
 		{
-			cfg: &xdsinternal.LBConfig{
-				ChildPolicy: &xdsinternal.LoadBalancingConfig{
+			cfg: &XDSConfig{
+				ChildPolicy: &loadBalancingConfig{
 					Name:   fakeBalancerA,
 					Config: json.RawMessage("{}"),
 				},
 			},
 			responseToSend: testEDSResp,
-			expectedChildPolicy: &xdsinternal.LoadBalancingConfig{
+			expectedChildPolicy: &loadBalancingConfig{
 				Name:   string(fakeBalancerA),
 				Config: json.RawMessage(`{}`),
 			},
 		},
 		{
-			cfg: &xdsinternal.LBConfig{
-				ChildPolicy: &xdsinternal.LoadBalancingConfig{
+			cfg: &XDSConfig{
+				ChildPolicy: &loadBalancingConfig{
 					Name:   fakeBalancerB,
 					Config: json.RawMessage("{}"),
 				},
 			},
-			expectedChildPolicy: &xdsinternal.LoadBalancingConfig{
+			expectedChildPolicy: &loadBalancingConfig{
 				Name:   string(fakeBalancerB),
 				Config: json.RawMessage(`{}`),
 			},
@@ -461,16 +466,16 @@ func (s) TestXdsBalanceHandleBalancerConfigFallBackUpdate(t *testing.T) {
 
 	addr, td, _, cleanup := setupServer(t)
 
-	cfg := xdsinternal.LBConfig{
+	cfg := XDSConfig{
 		BalancerName:   addr,
-		ChildPolicy:    &xdsinternal.LoadBalancingConfig{Name: fakeBalancerA},
-		FallBackPolicy: &xdsinternal.LoadBalancingConfig{Name: fakeBalancerA},
+		ChildPolicy:    &loadBalancingConfig{Name: fakeBalancerA},
+		FallBackPolicy: &loadBalancingConfig{Name: fakeBalancerA},
 	}
 	lb.UpdateClientConnState(balancer.ClientConnState{BalancerConfig: &cfg})
 
 	addrs := []resolver.Address{{Addr: "1.1.1.1:10001"}, {Addr: "2.2.2.2:10002"}, {Addr: "3.3.3.3:10003"}}
 	cfg2 := cfg
-	cfg2.FallBackPolicy = &xdsinternal.LoadBalancingConfig{Name: fakeBalancerB}
+	cfg2.FallBackPolicy = &loadBalancingConfig{Name: fakeBalancerB}
 	lb.UpdateClientConnState(balancer.ClientConnState{
 		ResolverState:  resolver.State{Addresses: addrs},
 		BalancerConfig: &cfg2,
@@ -502,7 +507,7 @@ func (s) TestXdsBalanceHandleBalancerConfigFallBackUpdate(t *testing.T) {
 	}
 
 	cfg3 := cfg
-	cfg3.FallBackPolicy = &xdsinternal.LoadBalancingConfig{Name: fakeBalancerA}
+	cfg3.FallBackPolicy = &loadBalancingConfig{Name: fakeBalancerA}
 	lb.UpdateClientConnState(balancer.ClientConnState{
 		ResolverState:  resolver.State{Addresses: addrs},
 		BalancerConfig: &cfg3,
@@ -536,10 +541,10 @@ func (s) TestXdsBalancerHandlerSubConnStateChange(t *testing.T) {
 
 	addr, td, _, cleanup := setupServer(t)
 	defer cleanup()
-	cfg := &xdsinternal.LBConfig{
+	cfg := &XDSConfig{
 		BalancerName:   addr,
-		ChildPolicy:    &xdsinternal.LoadBalancingConfig{Name: fakeBalancerA},
-		FallBackPolicy: &xdsinternal.LoadBalancingConfig{Name: fakeBalancerA},
+		ChildPolicy:    &loadBalancingConfig{Name: fakeBalancerA},
+		FallBackPolicy: &loadBalancingConfig{Name: fakeBalancerA},
 	}
 	lb.UpdateClientConnState(balancer.ClientConnState{BalancerConfig: cfg})
 
@@ -614,10 +619,10 @@ func (s) TestXdsBalancerFallBackSignalFromEdsBalancer(t *testing.T) {
 
 	addr, td, _, cleanup := setupServer(t)
 	defer cleanup()
-	cfg := &xdsinternal.LBConfig{
+	cfg := &XDSConfig{
 		BalancerName:   addr,
-		ChildPolicy:    &xdsinternal.LoadBalancingConfig{Name: fakeBalancerA},
-		FallBackPolicy: &xdsinternal.LoadBalancingConfig{Name: fakeBalancerA},
+		ChildPolicy:    &loadBalancingConfig{Name: fakeBalancerA},
+		FallBackPolicy: &loadBalancingConfig{Name: fakeBalancerA},
 	}
 	lb.UpdateClientConnState(balancer.ClientConnState{BalancerConfig: cfg})
 
@@ -675,43 +680,119 @@ func (s) TestXdsBalancerFallBackSignalFromEdsBalancer(t *testing.T) {
 	}
 }
 
-func (s) TestXdsBalancerConfigParsingSelectingLBPolicy(t *testing.T) {
-	js := json.RawMessage(`{
-"balancerName": "fake.foo.bar",
-"childPolicy": [{"fake_balancer_C": {}}, {"fake_balancer_A": {}}, {"fake_balancer_B": {}}],
-"fallbackPolicy": [{"fake_balancer_C": {}}, {"fake_balancer_B": {}}, {"fake_balancer_A": {}}]
-}`)
-	cfg, err := (&xdsBalancerBuilder{}).ParseConfig(js)
-	if err != nil {
-		t.Fatalf("unable to unmarshal balancer config into xds config: %v", err)
+func TestXdsBalancerConfigParsing(t *testing.T) {
+	const (
+		testEDSName = "eds.service"
+		testLRSName = "lrs.server"
+	)
+	b := bytes.NewBuffer(nil)
+	if err := (&jsonpb.Marshaler{}).Marshal(b, &scpb.XdsConfig{
+		ChildPolicy: []*scpb.LoadBalancingConfig{
+			{Policy: &scpb.LoadBalancingConfig_Xds{}},
+			{Policy: &scpb.LoadBalancingConfig_RoundRobin{
+				RoundRobin: &scpb.RoundRobinConfig{},
+			}},
+		},
+		FallbackPolicy: []*scpb.LoadBalancingConfig{
+			{Policy: &scpb.LoadBalancingConfig_Xds{}},
+			{Policy: &scpb.LoadBalancingConfig_PickFirst{
+				PickFirst: &scpb.PickFirstConfig{},
+			}},
+		},
+		EdsServiceName:             testEDSName,
+		LrsLoadReportingServerName: &wrapperspb.StringValue{Value: testLRSName},
+	}); err != nil {
+		t.Fatalf("%v", err)
 	}
-	xdsCfg := cfg.(*xdsinternal.LBConfig)
-	wantChildPolicy := &xdsinternal.LoadBalancingConfig{Name: string(fakeBalancerA), Config: json.RawMessage(`{}`)}
-	if !reflect.DeepEqual(xdsCfg.ChildPolicy, wantChildPolicy) {
-		t.Fatalf("got child policy %v, want %v", xdsCfg.ChildPolicy, wantChildPolicy)
+
+	tests := []struct {
+		name    string
+		js      json.RawMessage
+		want    serviceconfig.LoadBalancingConfig
+		wantErr bool
+	}{
+		{
+			name: "jsonpb-generated",
+			js:   b.Bytes(),
+			want: &XDSConfig{
+				ChildPolicy: &loadBalancingConfig{
+					Name:   "round_robin",
+					Config: json.RawMessage("{}"),
+				},
+				FallBackPolicy: &loadBalancingConfig{
+					Name:   "pick_first",
+					Config: json.RawMessage("{}"),
+				},
+				EDSServiceName:             testEDSName,
+				LrsLoadReportingServerName: testLRSName,
+			},
+			wantErr: false,
+		},
+		{
+			// json with random balancers, and the first is not registered.
+			name: "manually-generated",
+			js: json.RawMessage(`
+{
+  "balancerName": "fake.foo.bar",
+  "childPolicy": [
+    {"fake_balancer_C": {}},
+    {"fake_balancer_A": {}},
+    {"fake_balancer_B": {}}
+  ],
+  "fallbackPolicy": [
+    {"fake_balancer_C": {}},
+    {"fake_balancer_B": {}},
+    {"fake_balancer_A": {}}
+  ],
+  "edsServiceName": "eds.service",
+  "lrsLoadReportingServerName": "lrs.server"
+}`),
+			want: &XDSConfig{
+				BalancerName: "fake.foo.bar",
+				ChildPolicy: &loadBalancingConfig{
+					Name:   "fake_balancer_A",
+					Config: json.RawMessage("{}"),
+				},
+				FallBackPolicy: &loadBalancingConfig{
+					Name:   "fake_balancer_B",
+					Config: json.RawMessage("{}"),
+				},
+				EDSServiceName:             testEDSName,
+				LrsLoadReportingServerName: testLRSName,
+			},
+			wantErr: false,
+		},
 	}
-	wantFallbackPolicy := &xdsinternal.LoadBalancingConfig{Name: string(fakeBalancerB), Config: json.RawMessage(`{}`)}
-	if !reflect.DeepEqual(xdsCfg.FallBackPolicy, wantFallbackPolicy) {
-		t.Fatalf("got fallback policy %v, want %v", xdsCfg.FallBackPolicy, wantFallbackPolicy)
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			b := &xdsBalancerBuilder{}
+			got, err := b.ParseConfig(tt.js)
+			if (err != nil) != tt.wantErr {
+				t.Errorf("xdsBalancerBuilder.ParseConfig() error = %v, wantErr %v", err, tt.wantErr)
+				return
+			}
+			if !cmp.Equal(got, tt.want) {
+				t.Errorf(cmp.Diff(got, tt.want))
+			}
+		})
 	}
 }
-
-func (s) TestXdsLoadbalancingConfigParsing(t *testing.T) {
+func TestLoadbalancingConfigParsing(t *testing.T) {
 	tests := []struct {
 		name string
 		s    string
-		want *xdsinternal.LBConfig
+		want *XDSConfig
 	}{
 		{
 			name: "empty",
 			s:    "{}",
-			want: &xdsinternal.LBConfig{},
+			want: &XDSConfig{},
 		},
 		{
 			name: "success1",
 			s:    `{"childPolicy":[{"pick_first":{}}]}`,
-			want: &xdsinternal.LBConfig{
-				ChildPolicy: &xdsinternal.LoadBalancingConfig{
+			want: &XDSConfig{
+				ChildPolicy: &loadBalancingConfig{
 					Name:   "pick_first",
 					Config: json.RawMessage(`{}`),
 				},
@@ -720,8 +801,8 @@ func (s) TestXdsLoadbalancingConfigParsing(t *testing.T) {
 		{
 			name: "success2",
 			s:    `{"childPolicy":[{"round_robin":{}},{"pick_first":{}}]}`,
-			want: &xdsinternal.LBConfig{
-				ChildPolicy: &xdsinternal.LoadBalancingConfig{
+			want: &XDSConfig{
+				ChildPolicy: &loadBalancingConfig{
 					Name:   "round_robin",
 					Config: json.RawMessage(`{}`),
 				},
@@ -730,7 +811,7 @@ func (s) TestXdsLoadbalancingConfigParsing(t *testing.T) {
 	}
 	for _, tt := range tests {
 		t.Run(tt.name, func(t *testing.T) {
-			var cfg xdsinternal.LBConfig
+			var cfg XDSConfig
 			if err := json.Unmarshal([]byte(tt.s), &cfg); err != nil || !reflect.DeepEqual(&cfg, tt.want) {
 				t.Errorf("test name: %s, parseFullServiceConfig() = %+v, err: %v, want %+v, <nil>", tt.name, cfg, err, tt.want)
 			}

xds/internal/internal.go

@@ -18,12 +18,9 @@
 package internal
 
 import (
-	"encoding/json"
 	"fmt"
 
 	corepb "github.com/envoyproxy/go-control-plane/envoy/api/v2/core"
-	"google.golang.org/grpc/balancer"
-	"google.golang.org/grpc/serviceconfig"
 )
 
 // Locality is xds.Locality without XXX fields, so it can be used as map
@@ -51,88 +48,3 @@ func (lamk Locality) ToProto() *corepb.Locality {
 		SubZone: lamk.SubZone,
 	}
 }
-
-// LBConfig represents the loadBalancingConfig section of the service config
-// for xDS balancers.
-type LBConfig struct {
-	serviceconfig.LoadBalancingConfig
-	// BalancerName represents the load balancer to use.
-	BalancerName string
-	// ChildPolicy represents the load balancing config for the child policy.
-	ChildPolicy *LoadBalancingConfig
-	// FallBackPolicy represents the load balancing config for the fallback.
-	FallBackPolicy *LoadBalancingConfig
-}
-
-// UnmarshalJSON parses the JSON-encoded byte slice in data and stores it in l.
-// When unmarshalling, we iterate through the childPolicy/fallbackPolicy lists
-// and select the first LB policy which has been registered.
-func (l *LBConfig) UnmarshalJSON(data []byte) error {
-	var val map[string]json.RawMessage
-	if err := json.Unmarshal(data, &val); err != nil {
-		return err
-	}
-	for k, v := range val {
-		switch k {
-		case "balancerName":
-			if err := json.Unmarshal(v, &l.BalancerName); err != nil {
-				return err
-			}
-		case "childPolicy":
-			var lbcfgs []*LoadBalancingConfig
-			if err := json.Unmarshal(v, &lbcfgs); err != nil {
-				return err
-			}
-			for _, lbcfg := range lbcfgs {
-				if balancer.Get(lbcfg.Name) != nil {
-					l.ChildPolicy = lbcfg
-					break
-				}
-			}
-		case "fallbackPolicy":
-			var lbcfgs []*LoadBalancingConfig
-			if err := json.Unmarshal(v, &lbcfgs); err != nil {
-				return err
-			}
-			for _, lbcfg := range lbcfgs {
-				if balancer.Get(lbcfg.Name) != nil {
-					l.FallBackPolicy = lbcfg
-					break
-				}
-			}
-		}
-	}
-	return nil
-}
-
-// MarshalJSON returns a JSON encoding of l.
-func (l *LBConfig) MarshalJSON() ([]byte, error) {
-	return nil, nil
-}
-
-// LoadBalancingConfig represents a single load balancing config,
-// stored in JSON format.
-type LoadBalancingConfig struct {
-	Name   string
-	Config json.RawMessage
-}
-
-// MarshalJSON returns a JSON encoding of l.
-func (l *LoadBalancingConfig) MarshalJSON() ([]byte, error) {
-	m := make(map[string]json.RawMessage)
-	m[l.Name] = l.Config
-	return json.Marshal(m)
-}
-
-// UnmarshalJSON parses the JSON-encoded byte slice in data and stores it in l.
-func (l *LoadBalancingConfig) UnmarshalJSON(data []byte) error {
-	var cfg map[string]json.RawMessage
-	if err := json.Unmarshal(data, &cfg); err != nil {
-		return err
-	}
-	for name, config := range cfg {
-		l.Name = name
-		l.Config = config
-	}
-	return nil
-}

xds/internal/resolver/xds_resolver_test.go

@@ -31,7 +31,7 @@ import (
 	"google.golang.org/grpc/internal"
 	"google.golang.org/grpc/resolver"
 	"google.golang.org/grpc/serviceconfig"
-	xdsinternal "google.golang.org/grpc/xds/internal"
+	xdsbalancer "google.golang.org/grpc/xds/internal/balancer"
 )
 
 // This is initialized at init time.
@@ -118,7 +118,7 @@ func (*fakeBalancer) ResolverError(error) {
 	panic("unimplemented")
 }
 
-// UpdateClientConnState verifies that the received LBConfig matches the
+// UpdateClientConnState verifies that the received edsConfig matches the
 // provided one, and if not, sends an error on the provided channel.
 func (f *fakeBalancer) UpdateClientConnState(ccs balancer.ClientConnState) error {
 	gotLBConfig, ok := ccs.BalancerConfig.(*wrappedLBConfig)
@@ -127,7 +127,7 @@ func (f *fakeBalancer) UpdateClientConnState(ccs balancer.ClientConnState) error
 		return balancer.ErrBadResolverState
 	}
 
-	var gotCfg, wantCfg xdsinternal.LBConfig
+	var gotCfg, wantCfg xdsbalancer.XDSConfig
 	if err := wantCfg.UnmarshalJSON(f.wantLBConfig.lbCfg); err != nil {
 		f.errCh <- fmt.Errorf("unable to unmarshal balancer config %s into xds config", string(f.wantLBConfig.lbCfg))
 		return balancer.ErrBadResolverState
@@ -136,6 +136,7 @@ func (f *fakeBalancer) UpdateClientConnState(ccs balancer.ClientConnState) error
 		f.errCh <- fmt.Errorf("unable to unmarshal balancer config %s into xds config", string(gotLBConfig.lbCfg))
 		return balancer.ErrBadResolverState
 	}
+
 	if !reflect.DeepEqual(gotCfg, wantCfg) {
 		f.errCh <- fmt.Errorf("in fakeBalancer got lbConfig %v, want %v", gotCfg, wantCfg)
 		return balancer.ErrBadResolverState
@@ -171,7 +172,7 @@ func (f *fakeBalancerBuilder) ParseConfig(c json.RawMessage) (serviceconfig.Load
 }
 
 // wrappedLBConfig simply wraps the provided LB config with a
-// serviceconfig.LoadBalancingConfig interface.
+// serviceconfig.loadBalancingConfig interface.
 type wrappedLBConfig struct {
 	serviceconfig.LoadBalancingConfig
 	lbCfg json.RawMessage