Repository: grpc/grpc-go

Issue:
Buffer leak tests are not enabled
There is a GitHub workflow configured to run buffer leak detection: https://github.com/grpc/grpc-go/blob/e7a8097342e07dbfa093589eed67a8e0d6558423/.github/workflows/testing.yml#L58-L61

Here is the build tag that enabled the buffer leak detection: https://github.com/grpc/grpc-go/blob/e7a8097342e07dbfa093589eed67a8e0d6558423/internal/leakcheck/leakcheck_enabled.go#L1

The workflow is using the tag `buffer_pooling` while the build tag is `checkbuffers`.

Errors are reported after using the correct tag: https://github.com/grpc/grpc-go/actions/runs/11020737778/job/30606203907?pr=7670

From maintainers' group:
> We know there are some leaks in error situations. Paul had disabled it for some tests, but I think that stuff to disable it got torn out?
note that these leaks aren't actual memory leaks but just failure to re-use memory in some rare situations


Discussion:
@arjan-bal: @PapaCharlie would you be open to taking look at this?

Solution patch:
diff --git a/.github/workflows/testing.yml b/.github/workflows/testing.yml
index c5b7dd46..43717dbf 100644
--- a/.github/workflows/testing.yml
+++ b/.github/workflows/testing.yml
@@ -55,10 +55,6 @@ jobs:
             goversion: '1.23'
             testflags: -race
 
-          - type: tests
-            goversion: '1.23'
-            testflags: '-race -tags=buffer_pooling'
-
           - type: tests
             goversion: '1.23'
             goarch: 386
diff --git a/balancer/endpointsharding/endpointsharding.go b/balancer/endpointsharding/endpointsharding.go
index 8f28da75..8425ddea 100644
--- a/balancer/endpointsharding/endpointsharding.go
+++ b/balancer/endpointsharding/endpointsharding.go
@@ -28,7 +28,6 @@ package endpointsharding
 import (
 	"encoding/json"
 	"errors"
-	"fmt"
 	"math/rand"
 	"sync"
 	"sync/atomic"
@@ -80,20 +79,9 @@ type endpointSharding struct {
 // for endpoints that are no longer present. It also updates all the children,
 // and sends a single synchronous update of the childrens' aggregated state at
 // the end of the UpdateClientConnState operation. If any endpoint has no
-// addresses, returns error without forwarding any updates. Otherwise returns
-// first error found from a child, but fully processes the new update.
+// addresses it will ignore that endpoint. Otherwise, returns first error found
+// from a child, but fully processes the new update.
 func (es *endpointSharding) UpdateClientConnState(state balancer.ClientConnState) error {
-	if len(state.ResolverState.Endpoints) == 0 {
-		return errors.New("endpoints list is empty")
-	}
-	// Check/return early if any endpoints have no addresses.
-	// TODO: make this configurable if needed.
-	for i, endpoint := range state.ResolverState.Endpoints {
-		if len(endpoint.Addresses) == 0 {
-			return fmt.Errorf("endpoint %d has empty addresses", i)
-		}
-	}
-
 	es.inhibitChildUpdates.Store(true)
 	defer func() {
 		es.inhibitChildUpdates.Store(false)
@@ -106,6 +94,9 @@ func (es *endpointSharding) UpdateClientConnState(state balancer.ClientConnState
 
 	// Update/Create new children.
 	for _, endpoint := range state.ResolverState.Endpoints {
+		if len(endpoint.Addresses) == 0 {
+			continue
+		}
 		if _, ok := newChildren.Get(endpoint); ok {
 			// Endpoint child was already created, continue to avoid duplicate
 			// update.
diff --git a/balancer/rls/config.go b/balancer/rls/config.go
index 439581c7..ff540aa0 100644
--- a/balancer/rls/config.go
+++ b/balancer/rls/config.go
@@ -143,7 +143,10 @@ type lbConfigJSON struct {
 //	- childPolicyConfigTargetFieldName:
 //	  - must be set and non-empty
 func (rlsBB) ParseConfig(c json.RawMessage) (serviceconfig.LoadBalancingConfig, error) {
-	logger.Infof("Received JSON service config: %v", pretty.ToJSON(c))
+	if logger.V(2) {
+		logger.Infof("Received JSON service config: %v", pretty.ToJSON(c))
+	}
+
 	cfgJSON := &lbConfigJSON{}
 	if err := json.Unmarshal(c, cfgJSON); err != nil {
 		return nil, fmt.Errorf("rls: json unmarshal failed for service config %+v: %v", string(c), err)
diff --git a/balancer/rls/control_channel.go b/balancer/rls/control_channel.go
index 4acc11d9..f2ad8bc7 100644
--- a/balancer/rls/control_channel.go
+++ b/balancer/rls/control_channel.go
@@ -209,7 +209,9 @@ func (cc *controlChannel) lookup(reqKeys map[string]string, reason rlspb.RouteLo
 			Reason:          reason,
 			StaleHeaderData: staleHeaders,
 		}
-		cc.logger.Infof("Sending RLS request %+v", pretty.ToJSON(req))
+		if cc.logger.V(2) {
+			cc.logger.Infof("Sending RLS request %+v", pretty.ToJSON(req))
+		}
 
 		ctx, cancel := context.WithTimeout(context.Background(), cc.rpcTimeout)
 		defer cancel()
diff --git a/balancer/weightedtarget/weightedtarget.go b/balancer/weightedtarget/weightedtarget.go
index dfd1ef26..c004e112 100644
--- a/balancer/weightedtarget/weightedtarget.go
+++ b/balancer/weightedtarget/weightedtarget.go
@@ -99,7 +99,10 @@ func LocalityFromResolverState(state resolver.State) string {
 // creates/deletes sub-balancers and sends them update. addresses are split into
 // groups based on hierarchy path.
 func (b *weightedTargetBalancer) UpdateClientConnState(s balancer.ClientConnState) error {
-	b.logger.Infof("Received update from resolver, balancer config: %+v", pretty.ToJSON(s.BalancerConfig))
+	if b.logger.V(2) {
+		b.logger.Infof("Received update from resolver, balancer config: %+v", pretty.ToJSON(s.BalancerConfig))
+	}
+
 	newConfig, ok := s.BalancerConfig.(*LBConfig)
 	if !ok {
 		return fmt.Errorf("unexpected balancer config with type: %T", s.BalancerConfig)
diff --git a/credentials/google/google.go b/credentials/google/google.go
index fbdf7dc2..2f1ac674 100644
--- a/credentials/google/google.go
+++ b/credentials/google/google.go
@@ -39,6 +39,9 @@ var logger = grpclog.Component("credentials")
 type DefaultCredentialsOptions struct {
 	// PerRPCCreds is a per RPC credentials that is passed to a bundle.
 	PerRPCCreds credentials.PerRPCCredentials
+	// ALTSPerRPCCreds is a per RPC credentials that, if specified, will
+	// supercede PerRPCCreds above for and only for ALTS connections.
+	ALTSPerRPCCreds credentials.PerRPCCredentials
 }
 
 // NewDefaultCredentialsWithOptions returns a credentials bundle that is
@@ -55,6 +58,12 @@ func NewDefaultCredentialsWithOptions(opts DefaultCredentialsOptions) credential
 			logger.Warningf("NewDefaultCredentialsWithOptions: failed to create application oauth: %v", err)
 		}
 	}
+	if opts.ALTSPerRPCCreds != nil {
+		opts.PerRPCCreds = &dualPerRPCCreds{
+			perRPCCreds:     opts.PerRPCCreds,
+			altsPerRPCCreds: opts.ALTSPerRPCCreds,
+		}
+	}
 	c := &creds{opts: opts}
 	bundle, err := c.NewWithMode(internal.CredsBundleModeFallback)
 	if err != nil {
@@ -143,3 +152,27 @@ func (c *creds) NewWithMode(mode string) (credentials.Bundle, error) {
 
 	return newCreds, nil
 }
+
+// dualPerRPCCreds implements credentials.PerRPCCredentials by embedding the
+// fallback PerRPCCredentials and the ALTS one. It pickes one of them based on
+// the channel type.
+type dualPerRPCCreds struct {
+	perRPCCreds     credentials.PerRPCCredentials
+	altsPerRPCCreds credentials.PerRPCCredentials
+}
+
+func (d *dualPerRPCCreds) GetRequestMetadata(ctx context.Context, uri ...string) (map[string]string, error) {
+	ri, ok := credentials.RequestInfoFromContext(ctx)
+	if !ok {
+		return nil, fmt.Errorf("request info not found from context")
+	}
+	if authType := ri.AuthInfo.AuthType(); authType == "alts" {
+		return d.altsPerRPCCreds.GetRequestMetadata(ctx, uri...)
+	}
+	// This ensures backward compatibility even if authType is not "tls".
+	return d.perRPCCreds.GetRequestMetadata(ctx, uri...)
+}
+
+func (d *dualPerRPCCreds) RequireTransportSecurity() bool {
+	return d.altsPerRPCCreds.RequireTransportSecurity() || d.perRPCCreds.RequireTransportSecurity()
+}
diff --git a/examples/go.mod b/examples/go.mod
index 0dd53bee..52451c85 100644
--- a/examples/go.mod
+++ b/examples/go.mod
@@ -12,7 +12,6 @@ require (
 	google.golang.org/grpc v1.67.1
 	google.golang.org/grpc/gcp/observability v1.0.1
 	google.golang.org/grpc/security/advancedtls v1.0.0
-	google.golang.org/grpc/stats/opentelemetry v0.0.0-20241017035653-830135e6c5a3
 	google.golang.org/protobuf v1.35.1
 )
 
diff --git a/examples/go.sum b/examples/go.sum
index 182b57b2..5bfb0231 100644
--- a/examples/go.sum
+++ b/examples/go.sum
@@ -220,6 +220,7 @@ cloud.google.com/go/compute/metadata v0.2.0/go.mod h1:zFmK7XCadkQkj6TtorcaGlCW1h
 cloud.google.com/go/compute/metadata v0.2.1/go.mod h1:jgHgmJd2RKBGzXqF5LR2EZMGxBkeanZ9wwa75XHJgOM=
 cloud.google.com/go/compute/metadata v0.2.3/go.mod h1:VAV5nSsACxMJvgaAuX6Pk2AawlZn8kiOGuCv6gTkwuA=
 cloud.google.com/go/compute/metadata v0.3.0/go.mod h1:zFmK7XCadkQkj6TtorcaGlCW1hT1fIilQDwofLpJ20k=
+cloud.google.com/go/compute/metadata v0.5.0/go.mod h1:aHnloV2TPI38yx4s9+wAZhHykWvVCfu7hQbF+9CWoiY=
 cloud.google.com/go/compute/metadata v0.5.2 h1:UxK4uu/Tn+I3p2dYWTfiX4wva7aYlKixAHn3fyqngqo=
 cloud.google.com/go/compute/metadata v0.5.2/go.mod h1:C66sj2AluDcIqakBq/M8lw8/ybHgOZqin2obFxa/E5k=
 cloud.google.com/go/contactcenterinsights v1.3.0/go.mod h1:Eu2oemoePuEFc/xKFPjbTuPSj0fYJcPls9TFlPNnHHY=
@@ -776,6 +777,7 @@ gioui.org v0.0.0-20210308172011-57750fc8a0a6/go.mod h1:RSH6KIUZ0p2xy5zHDxgAM4zum
 git.sr.ht/~sbinet/gg v0.3.1/go.mod h1:KGYtlADtqsqANL9ueOFkWymvzUvLMQllU5Ixo+8v3pc=
 github.com/BurntSushi/toml v0.3.1/go.mod h1:xHWCNGjB5oqiDr8zfno3MHue2Ht5sIBksp03qcyfWMU=
 github.com/BurntSushi/xgb v0.0.0-20160522181843-27f122750802/go.mod h1:IVnqGOEym/WlBOVXweHU+Q+/VP0lqqI8lqeDx9IjBqo=
+github.com/GoogleCloudPlatform/opentelemetry-operations-go/detectors/gcp v1.24.2/go.mod h1:itPGVDKf9cC/ov4MdvJ2QZ0khw4bfoo9jzwTJlaxy2k=
 github.com/GoogleCloudPlatform/opentelemetry-operations-go/detectors/gcp v1.24.3 h1:cb3br57K508pQEFgBxn9GDhPS9HefpyMPK1RzmtMNzk=
 github.com/GoogleCloudPlatform/opentelemetry-operations-go/detectors/gcp v1.24.3/go.mod h1:itPGVDKf9cC/ov4MdvJ2QZ0khw4bfoo9jzwTJlaxy2k=
 github.com/JohnCGriffin/overflow v0.0.0-20211019200055-46fa312c352c/go.mod h1:X0CRv0ky0k6m906ixxpzmDRLvX58TFUKS2eePweuyxk=
@@ -1078,6 +1080,7 @@ github.com/rogpeppe/fastuuid v1.2.0/go.mod h1:jVj6XXZzXRy/MSR5jhDC/2q6DgLz+nrA6L
 github.com/rogpeppe/go-internal v1.3.0/go.mod h1:M8bDsm7K2OlrFYOpmOWEs/qY81heoFRclV5y23lUDJ4=
 github.com/rogpeppe/go-internal v1.6.1/go.mod h1:xXDCJY+GAPziupqXw64V24skbSoqbTEfhy4qGm1nDQc=
 github.com/rogpeppe/go-internal v1.9.0/go.mod h1:WtVeX8xhTBvf0smdhujwtBcq4Qrzq/fJaraNFVN+nFs=
+github.com/rogpeppe/go-internal v1.10.0/go.mod h1:UQnix2H7Ngw/k4C5ijL5+65zddjncjaFoBhdsK/akog=
 github.com/ruudk/golang-pdf417 v0.0.0-20181029194003-1af4ab5afa58/go.mod h1:6lfFZQK844Gfx8o5WFuvpxWRwnSoipWe/p622j1v06w=
 github.com/ruudk/golang-pdf417 v0.0.0-20201230142125-a7e3863a1245/go.mod h1:pQAZKsJ8yyVxGRWYNEm9oFB8ieLgKFnamEyDmSA0BRk=
 github.com/spf13/afero v1.3.3/go.mod h1:5KUK8ByomD5Ti5Artl0RtHeI5pTF7MIDuXL3yY520V4=
@@ -1433,6 +1436,7 @@ golang.org/x/sys v0.17.0/go.mod h1:/VUhepiaJMQUp4+oa/7Zr1D23ma6VTLIYjOOTFZPUcA=
 golang.org/x/sys v0.18.0/go.mod h1:/VUhepiaJMQUp4+oa/7Zr1D23ma6VTLIYjOOTFZPUcA=
 golang.org/x/sys v0.20.0/go.mod h1:/VUhepiaJMQUp4+oa/7Zr1D23ma6VTLIYjOOTFZPUcA=
 golang.org/x/sys v0.21.0/go.mod h1:/VUhepiaJMQUp4+oa/7Zr1D23ma6VTLIYjOOTFZPUcA=
+golang.org/x/sys v0.22.0/go.mod h1:/VUhepiaJMQUp4+oa/7Zr1D23ma6VTLIYjOOTFZPUcA=
 golang.org/x/sys v0.23.0/go.mod h1:/VUhepiaJMQUp4+oa/7Zr1D23ma6VTLIYjOOTFZPUcA=
 golang.org/x/sys v0.24.0/go.mod h1:/VUhepiaJMQUp4+oa/7Zr1D23ma6VTLIYjOOTFZPUcA=
 golang.org/x/sys v0.25.0/go.mod h1:/VUhepiaJMQUp4+oa/7Zr1D23ma6VTLIYjOOTFZPUcA=
diff --git a/gcp/observability/go.sum b/gcp/observability/go.sum
index a328c205..30e984fb 100644
--- a/gcp/observability/go.sum
+++ b/gcp/observability/go.sum
@@ -219,6 +219,7 @@ cloud.google.com/go/compute/metadata v0.2.0/go.mod h1:zFmK7XCadkQkj6TtorcaGlCW1h
 cloud.google.com/go/compute/metadata v0.2.1/go.mod h1:jgHgmJd2RKBGzXqF5LR2EZMGxBkeanZ9wwa75XHJgOM=
 cloud.google.com/go/compute/metadata v0.2.3/go.mod h1:VAV5nSsACxMJvgaAuX6Pk2AawlZn8kiOGuCv6gTkwuA=
 cloud.google.com/go/compute/metadata v0.3.0/go.mod h1:zFmK7XCadkQkj6TtorcaGlCW1hT1fIilQDwofLpJ20k=
+cloud.google.com/go/compute/metadata v0.5.0/go.mod h1:aHnloV2TPI38yx4s9+wAZhHykWvVCfu7hQbF+9CWoiY=
 cloud.google.com/go/compute/metadata v0.5.2 h1:UxK4uu/Tn+I3p2dYWTfiX4wva7aYlKixAHn3fyqngqo=
 cloud.google.com/go/compute/metadata v0.5.2/go.mod h1:C66sj2AluDcIqakBq/M8lw8/ybHgOZqin2obFxa/E5k=
 cloud.google.com/go/contactcenterinsights v1.3.0/go.mod h1:Eu2oemoePuEFc/xKFPjbTuPSj0fYJcPls9TFlPNnHHY=
@@ -775,6 +776,7 @@ gioui.org v0.0.0-20210308172011-57750fc8a0a6/go.mod h1:RSH6KIUZ0p2xy5zHDxgAM4zum
 git.sr.ht/~sbinet/gg v0.3.1/go.mod h1:KGYtlADtqsqANL9ueOFkWymvzUvLMQllU5Ixo+8v3pc=
 github.com/BurntSushi/toml v0.3.1/go.mod h1:xHWCNGjB5oqiDr8zfno3MHue2Ht5sIBksp03qcyfWMU=
 github.com/BurntSushi/xgb v0.0.0-20160522181843-27f122750802/go.mod h1:IVnqGOEym/WlBOVXweHU+Q+/VP0lqqI8lqeDx9IjBqo=
+github.com/GoogleCloudPlatform/opentelemetry-operations-go/detectors/gcp v1.24.2/go.mod h1:itPGVDKf9cC/ov4MdvJ2QZ0khw4bfoo9jzwTJlaxy2k=
 github.com/JohnCGriffin/overflow v0.0.0-20211019200055-46fa312c352c/go.mod h1:X0CRv0ky0k6m906ixxpzmDRLvX58TFUKS2eePweuyxk=
 github.com/ajstarks/deck v0.0.0-20200831202436-30c9fc6549a9/go.mod h1:JynElWSGnm/4RlzPXRlREEwqTHAN3T56Bv2ITsFT3gY=
 github.com/ajstarks/deck/generate v0.0.0-20210309230005-c3f852c02e19/go.mod h1:T13YZdzov6OU0A1+RfKZiZN9ca6VeKdBdyDV+BY97Tk=
@@ -1054,6 +1056,7 @@ github.com/rogpeppe/fastuuid v1.2.0/go.mod h1:jVj6XXZzXRy/MSR5jhDC/2q6DgLz+nrA6L
 github.com/rogpeppe/go-internal v1.3.0/go.mod h1:M8bDsm7K2OlrFYOpmOWEs/qY81heoFRclV5y23lUDJ4=
 github.com/rogpeppe/go-internal v1.6.1/go.mod h1:xXDCJY+GAPziupqXw64V24skbSoqbTEfhy4qGm1nDQc=
 github.com/rogpeppe/go-internal v1.9.0/go.mod h1:WtVeX8xhTBvf0smdhujwtBcq4Qrzq/fJaraNFVN+nFs=
+github.com/rogpeppe/go-internal v1.10.0/go.mod h1:UQnix2H7Ngw/k4C5ijL5+65zddjncjaFoBhdsK/akog=
 github.com/ruudk/golang-pdf417 v0.0.0-20181029194003-1af4ab5afa58/go.mod h1:6lfFZQK844Gfx8o5WFuvpxWRwnSoipWe/p622j1v06w=
 github.com/ruudk/golang-pdf417 v0.0.0-20201230142125-a7e3863a1245/go.mod h1:pQAZKsJ8yyVxGRWYNEm9oFB8ieLgKFnamEyDmSA0BRk=
 github.com/spf13/afero v1.3.3/go.mod h1:5KUK8ByomD5Ti5Artl0RtHeI5pTF7MIDuXL3yY520V4=
@@ -1093,6 +1096,7 @@ go.opencensus.io v0.22.5/go.mod h1:5pWMHQbX5EPX2/62yrJeAkowc+lfs/XD7Uxpq3pI6kk=
 go.opencensus.io v0.23.0/go.mod h1:XItmlyltB5F7CS4xOC1DcqMoFqwtC6OG2xF7mCv7P7E=
 go.opencensus.io v0.24.0 h1:y73uSU6J157QMP2kn2r30vwW1A2W2WFwSCGnAVxeaD0=
 go.opencensus.io v0.24.0/go.mod h1:vNK8G9p7aAivkbmorf4v+7Hgx+Zs0yY+0fOtgBfjQKo=
+go.opentelemetry.io/contrib/detectors/gcp v1.31.0/go.mod h1:tzQL6E1l+iV44YFTkcAeNQqzXUiekSYP9jjJjXwEd00=
 go.opentelemetry.io/contrib/instrumentation/google.golang.org/grpc/otelgrpc v0.56.0 h1:yMkBS9yViCc7U7yeLzJPM2XizlfdVvBRSmsQDWu6qc0=
 go.opentelemetry.io/contrib/instrumentation/google.golang.org/grpc/otelgrpc v0.56.0/go.mod h1:n8MR6/liuGB5EmTETUBeU5ZgqMOlqKRxUaqPQBOANZ8=
 go.opentelemetry.io/contrib/instrumentation/net/http/otelhttp v0.56.0 h1:UP6IpuHFkUgOQL9FFQFrZ+5LiwhhYRbi7VZSIx6Nj5s=
@@ -1101,8 +1105,9 @@ go.opentelemetry.io/otel v1.31.0 h1:NsJcKPIW0D0H3NgzPDHmo0WW6SptzPdqg/L1zsIm2hY=
 go.opentelemetry.io/otel v1.31.0/go.mod h1:O0C14Yl9FgkjqcCZAsE053C13OaddMYr/hz6clDkEJE=
 go.opentelemetry.io/otel/metric v1.31.0 h1:FSErL0ATQAmYHUIzSezZibnyVlft1ybhy4ozRPcF2fE=
 go.opentelemetry.io/otel/metric v1.31.0/go.mod h1:C3dEloVbLuYoX41KpmAhOqNriGbA+qqH6PQ5E5mUfnY=
-go.opentelemetry.io/otel/sdk v1.29.0 h1:vkqKjk7gwhS8VaWb0POZKmIEDimRCMsopNYnriHyryo=
-go.opentelemetry.io/otel/sdk v1.29.0/go.mod h1:pM8Dx5WKnvxLCb+8lG1PRNIDxu9g9b9g59Qr7hfAAok=
+go.opentelemetry.io/otel/sdk v1.31.0 h1:xLY3abVHYZ5HSfOg3l2E5LUj2Cwva5Y7yGxnSW9H5Gk=
+go.opentelemetry.io/otel/sdk v1.31.0/go.mod h1:TfRbMdhvxIIr/B2N2LQW2S5v9m3gOQ/08KsbbO5BPT0=
+go.opentelemetry.io/otel/sdk/metric v1.31.0/go.mod h1:CRInTMVvNhUKgSAMbKyTMxqOBC0zgyxzW55lZzX43Y8=
 go.opentelemetry.io/otel/trace v1.31.0 h1:ffjsj1aRouKewfr85U2aGagJ46+MvodynlQ1HYdmJys=
 go.opentelemetry.io/otel/trace v1.31.0/go.mod h1:TXZkRk7SM2ZQLtR6eoAWQFIHPvzQ06FJAsO1tJg480A=
 go.opentelemetry.io/proto/otlp v0.7.0/go.mod h1:PqfVotwruBrMGOCsRd/89rSnXhoiJIqeYNgFYFoEGnI=
@@ -1403,6 +1408,7 @@ golang.org/x/sys v0.17.0/go.mod h1:/VUhepiaJMQUp4+oa/7Zr1D23ma6VTLIYjOOTFZPUcA=
 golang.org/x/sys v0.18.0/go.mod h1:/VUhepiaJMQUp4+oa/7Zr1D23ma6VTLIYjOOTFZPUcA=
 golang.org/x/sys v0.20.0/go.mod h1:/VUhepiaJMQUp4+oa/7Zr1D23ma6VTLIYjOOTFZPUcA=
 golang.org/x/sys v0.21.0/go.mod h1:/VUhepiaJMQUp4+oa/7Zr1D23ma6VTLIYjOOTFZPUcA=
+golang.org/x/sys v0.22.0/go.mod h1:/VUhepiaJMQUp4+oa/7Zr1D23ma6VTLIYjOOTFZPUcA=
 golang.org/x/sys v0.23.0/go.mod h1:/VUhepiaJMQUp4+oa/7Zr1D23ma6VTLIYjOOTFZPUcA=
 golang.org/x/sys v0.24.0/go.mod h1:/VUhepiaJMQUp4+oa/7Zr1D23ma6VTLIYjOOTFZPUcA=
 golang.org/x/sys v0.25.0/go.mod h1:/VUhepiaJMQUp4+oa/7Zr1D23ma6VTLIYjOOTFZPUcA=
diff --git a/go.mod b/go.mod
index 80f75508..91008eeb 100644
--- a/go.mod
+++ b/go.mod
@@ -10,6 +10,11 @@ require (
 	github.com/golang/protobuf v1.5.4
 	github.com/google/go-cmp v0.6.0
 	github.com/google/uuid v1.6.0
+	go.opentelemetry.io/contrib/detectors/gcp v1.31.0
+	go.opentelemetry.io/otel v1.31.0
+	go.opentelemetry.io/otel/metric v1.31.0
+	go.opentelemetry.io/otel/sdk v1.31.0
+	go.opentelemetry.io/otel/sdk/metric v1.31.0
 	golang.org/x/net v0.30.0
 	golang.org/x/oauth2 v0.23.0
 	golang.org/x/sync v0.8.0
@@ -21,9 +26,13 @@ require (
 require (
 	cel.dev/expr v0.16.2 // indirect
 	cloud.google.com/go/compute/metadata v0.5.2 // indirect
+	github.com/GoogleCloudPlatform/opentelemetry-operations-go/detectors/gcp v1.24.2 // indirect
 	github.com/census-instrumentation/opencensus-proto v0.4.1 // indirect
 	github.com/envoyproxy/protoc-gen-validate v1.1.0 // indirect
+	github.com/go-logr/logr v1.4.2 // indirect
+	github.com/go-logr/stdr v1.2.2 // indirect
 	github.com/planetscale/vtprotobuf v0.6.1-0.20240319094008-0393e58bdf10 // indirect
+	go.opentelemetry.io/otel/trace v1.31.0 // indirect
 	golang.org/x/text v0.19.0 // indirect
 	google.golang.org/genproto/googleapis/api v0.0.0-20241015192408-796eee8c2d53 // indirect
 )
diff --git a/go.sum b/go.sum
index 8ed71623..fe263da6 100644
--- a/go.sum
+++ b/go.sum
@@ -2,6 +2,8 @@ cel.dev/expr v0.16.2 h1:RwRhoH17VhAu9U5CMvMhH1PDVgf0tuz9FT+24AfMLfU=
 cel.dev/expr v0.16.2/go.mod h1:gXngZQMkWJoSbE8mOzehJlXQyubn/Vg0vR9/F3W7iw8=
 cloud.google.com/go/compute/metadata v0.5.2 h1:UxK4uu/Tn+I3p2dYWTfiX4wva7aYlKixAHn3fyqngqo=
 cloud.google.com/go/compute/metadata v0.5.2/go.mod h1:C66sj2AluDcIqakBq/M8lw8/ybHgOZqin2obFxa/E5k=
+github.com/GoogleCloudPlatform/opentelemetry-operations-go/detectors/gcp v1.24.2 h1:cZpsGsWTIFKymTA0je7IIvi1O7Es7apb9CF3EQlOcfE=
+github.com/GoogleCloudPlatform/opentelemetry-operations-go/detectors/gcp v1.24.2/go.mod h1:itPGVDKf9cC/ov4MdvJ2QZ0khw4bfoo9jzwTJlaxy2k=
 github.com/census-instrumentation/opencensus-proto v0.4.1 h1:iKLQ0xPNFxR/2hzXZMrBo8f1j86j5WHzznCCQxV/b8g=
 github.com/census-instrumentation/opencensus-proto v0.4.1/go.mod h1:4T9NM4+4Vw91VeyqjLS6ao50K5bOcLKN6Q42XnYaRYw=
 github.com/cespare/xxhash/v2 v2.3.0 h1:UL815xU9SqsFlibzuggzjXhog7bL6oX9BbNZnL2UFvs=
@@ -14,6 +16,11 @@ github.com/envoyproxy/go-control-plane v0.13.1 h1:vPfJZCkob6yTMEgS+0TwfTUfbHjfy/
 github.com/envoyproxy/go-control-plane v0.13.1/go.mod h1:X45hY0mufo6Fd0KW3rqsGvQMw58jvjymeCzBU3mWyHw=
 github.com/envoyproxy/protoc-gen-validate v1.1.0 h1:tntQDh69XqOCOZsDz0lVJQez/2L6Uu2PdjCQwWCJ3bM=
 github.com/envoyproxy/protoc-gen-validate v1.1.0/go.mod h1:sXRDRVmzEbkM7CVcM06s9shE/m23dg3wzjl0UWqJ2q4=
+github.com/go-logr/logr v1.2.2/go.mod h1:jdQByPbusPIv2/zmleS9BjJVeZ6kBagPoEUsqbVz/1A=
+github.com/go-logr/logr v1.4.2 h1:6pFjapn8bFcIbiKo3XT4j/BhANplGihG6tvd+8rYgrY=
+github.com/go-logr/logr v1.4.2/go.mod h1:9T104GzyrTigFIr8wt5mBrctHMim0Nb2HLGrmQ40KvY=
+github.com/go-logr/stdr v1.2.2 h1:hSWxHoqTgW2S2qGc0LTAI563KZ5YKYRhT3MFKZMbjag=
+github.com/go-logr/stdr v1.2.2/go.mod h1:mMo/vtBO5dYbehREoey6XUKy/eSumjCCveDpRre4VKE=
 github.com/golang/glog v1.2.2 h1:1+mZ9upx1Dh6FmUTFR1naJ77miKiXgALjWOZ3NVFPmY=
 github.com/golang/glog v1.2.2/go.mod h1:6AhwSGph0fcJtXVM/PEHPqZlFeoLxhs7/t5UDAwmO+w=
 github.com/golang/protobuf v1.5.4 h1:i7eJL8qZTpSEXOPTxNKhASYpMn+8e5Q6AdndVa1dWek=
@@ -28,6 +35,18 @@ github.com/pmezard/go-difflib v1.0.0 h1:4DBwDE0NGyQoBHbLQYPwSUPoCMWR5BEzIk/f1lZb
 github.com/pmezard/go-difflib v1.0.0/go.mod h1:iKH77koFhYxTK1pcRnkKkqfTogsbg7gZNVY4sRDYZ/4=
 github.com/stretchr/testify v1.9.0 h1:HtqpIVDClZ4nwg75+f6Lvsy/wHu+3BoSGCbBAcpTsTg=
 github.com/stretchr/testify v1.9.0/go.mod h1:r2ic/lqez/lEtzL7wO/rwa5dbSLXVDPFyf8C91i36aY=
+go.opentelemetry.io/contrib/detectors/gcp v1.31.0 h1:G1JQOreVrfhRkner+l4mrGxmfqYCAuy76asTDAo0xsA=
+go.opentelemetry.io/contrib/detectors/gcp v1.31.0/go.mod h1:tzQL6E1l+iV44YFTkcAeNQqzXUiekSYP9jjJjXwEd00=
+go.opentelemetry.io/otel v1.31.0 h1:NsJcKPIW0D0H3NgzPDHmo0WW6SptzPdqg/L1zsIm2hY=
+go.opentelemetry.io/otel v1.31.0/go.mod h1:O0C14Yl9FgkjqcCZAsE053C13OaddMYr/hz6clDkEJE=
+go.opentelemetry.io/otel/metric v1.31.0 h1:FSErL0ATQAmYHUIzSezZibnyVlft1ybhy4ozRPcF2fE=
+go.opentelemetry.io/otel/metric v1.31.0/go.mod h1:C3dEloVbLuYoX41KpmAhOqNriGbA+qqH6PQ5E5mUfnY=
+go.opentelemetry.io/otel/sdk v1.31.0 h1:xLY3abVHYZ5HSfOg3l2E5LUj2Cwva5Y7yGxnSW9H5Gk=
+go.opentelemetry.io/otel/sdk v1.31.0/go.mod h1:TfRbMdhvxIIr/B2N2LQW2S5v9m3gOQ/08KsbbO5BPT0=
+go.opentelemetry.io/otel/sdk/metric v1.31.0 h1:i9hxxLJF/9kkvfHppyLL55aW7iIJz4JjxTeYusH7zMc=
+go.opentelemetry.io/otel/sdk/metric v1.31.0/go.mod h1:CRInTMVvNhUKgSAMbKyTMxqOBC0zgyxzW55lZzX43Y8=
+go.opentelemetry.io/otel/trace v1.31.0 h1:ffjsj1aRouKewfr85U2aGagJ46+MvodynlQ1HYdmJys=
+go.opentelemetry.io/otel/trace v1.31.0/go.mod h1:TXZkRk7SM2ZQLtR6eoAWQFIHPvzQ06FJAsO1tJg480A=
 go.uber.org/goleak v1.3.0 h1:2K3zAYmnTNqV73imy9J1T3WC+gmCePx2hEGkimedGto=
 go.uber.org/goleak v1.3.0/go.mod h1:CoHD4mav9JJNrW/WLlf7HGZPjdw8EucARQHekz1X6bE=
 golang.org/x/net v0.30.0 h1:AcW1SDZMkb8IpzCdQUaIq2sP4sZ4zw+55h6ynffypl4=
diff --git a/interop/observability/go.sum b/interop/observability/go.sum
index fc68e26e..a749b30f 100644
--- a/interop/observability/go.sum
+++ b/interop/observability/go.sum
@@ -219,6 +219,7 @@ cloud.google.com/go/compute/metadata v0.2.0/go.mod h1:zFmK7XCadkQkj6TtorcaGlCW1h
 cloud.google.com/go/compute/metadata v0.2.1/go.mod h1:jgHgmJd2RKBGzXqF5LR2EZMGxBkeanZ9wwa75XHJgOM=
 cloud.google.com/go/compute/metadata v0.2.3/go.mod h1:VAV5nSsACxMJvgaAuX6Pk2AawlZn8kiOGuCv6gTkwuA=
 cloud.google.com/go/compute/metadata v0.3.0/go.mod h1:zFmK7XCadkQkj6TtorcaGlCW1hT1fIilQDwofLpJ20k=
+cloud.google.com/go/compute/metadata v0.5.0/go.mod h1:aHnloV2TPI38yx4s9+wAZhHykWvVCfu7hQbF+9CWoiY=
 cloud.google.com/go/compute/metadata v0.5.2 h1:UxK4uu/Tn+I3p2dYWTfiX4wva7aYlKixAHn3fyqngqo=
 cloud.google.com/go/compute/metadata v0.5.2/go.mod h1:C66sj2AluDcIqakBq/M8lw8/ybHgOZqin2obFxa/E5k=
 cloud.google.com/go/contactcenterinsights v1.3.0/go.mod h1:Eu2oemoePuEFc/xKFPjbTuPSj0fYJcPls9TFlPNnHHY=
@@ -775,6 +776,7 @@ gioui.org v0.0.0-20210308172011-57750fc8a0a6/go.mod h1:RSH6KIUZ0p2xy5zHDxgAM4zum
 git.sr.ht/~sbinet/gg v0.3.1/go.mod h1:KGYtlADtqsqANL9ueOFkWymvzUvLMQllU5Ixo+8v3pc=
 github.com/BurntSushi/toml v0.3.1/go.mod h1:xHWCNGjB5oqiDr8zfno3MHue2Ht5sIBksp03qcyfWMU=
 github.com/BurntSushi/xgb v0.0.0-20160522181843-27f122750802/go.mod h1:IVnqGOEym/WlBOVXweHU+Q+/VP0lqqI8lqeDx9IjBqo=
+github.com/GoogleCloudPlatform/opentelemetry-operations-go/detectors/gcp v1.24.2/go.mod h1:itPGVDKf9cC/ov4MdvJ2QZ0khw4bfoo9jzwTJlaxy2k=
 github.com/JohnCGriffin/overflow v0.0.0-20211019200055-46fa312c352c/go.mod h1:X0CRv0ky0k6m906ixxpzmDRLvX58TFUKS2eePweuyxk=
 github.com/ajstarks/deck v0.0.0-20200831202436-30c9fc6549a9/go.mod h1:JynElWSGnm/4RlzPXRlREEwqTHAN3T56Bv2ITsFT3gY=
 github.com/ajstarks/deck/generate v0.0.0-20210309230005-c3f852c02e19/go.mod h1:T13YZdzov6OU0A1+RfKZiZN9ca6VeKdBdyDV+BY97Tk=
@@ -1056,6 +1058,7 @@ github.com/rogpeppe/fastuuid v1.2.0/go.mod h1:jVj6XXZzXRy/MSR5jhDC/2q6DgLz+nrA6L
 github.com/rogpeppe/go-internal v1.3.0/go.mod h1:M8bDsm7K2OlrFYOpmOWEs/qY81heoFRclV5y23lUDJ4=
 github.com/rogpeppe/go-internal v1.6.1/go.mod h1:xXDCJY+GAPziupqXw64V24skbSoqbTEfhy4qGm1nDQc=
 github.com/rogpeppe/go-internal v1.9.0/go.mod h1:WtVeX8xhTBvf0smdhujwtBcq4Qrzq/fJaraNFVN+nFs=
+github.com/rogpeppe/go-internal v1.10.0/go.mod h1:UQnix2H7Ngw/k4C5ijL5+65zddjncjaFoBhdsK/akog=
 github.com/ruudk/golang-pdf417 v0.0.0-20181029194003-1af4ab5afa58/go.mod h1:6lfFZQK844Gfx8o5WFuvpxWRwnSoipWe/p622j1v06w=
 github.com/ruudk/golang-pdf417 v0.0.0-20201230142125-a7e3863a1245/go.mod h1:pQAZKsJ8yyVxGRWYNEm9oFB8ieLgKFnamEyDmSA0BRk=
 github.com/spf13/afero v1.3.3/go.mod h1:5KUK8ByomD5Ti5Artl0RtHeI5pTF7MIDuXL3yY520V4=
@@ -1095,6 +1098,7 @@ go.opencensus.io v0.22.5/go.mod h1:5pWMHQbX5EPX2/62yrJeAkowc+lfs/XD7Uxpq3pI6kk=
 go.opencensus.io v0.23.0/go.mod h1:XItmlyltB5F7CS4xOC1DcqMoFqwtC6OG2xF7mCv7P7E=
 go.opencensus.io v0.24.0 h1:y73uSU6J157QMP2kn2r30vwW1A2W2WFwSCGnAVxeaD0=
 go.opencensus.io v0.24.0/go.mod h1:vNK8G9p7aAivkbmorf4v+7Hgx+Zs0yY+0fOtgBfjQKo=
+go.opentelemetry.io/contrib/detectors/gcp v1.31.0/go.mod h1:tzQL6E1l+iV44YFTkcAeNQqzXUiekSYP9jjJjXwEd00=
 go.opentelemetry.io/contrib/instrumentation/google.golang.org/grpc/otelgrpc v0.56.0 h1:yMkBS9yViCc7U7yeLzJPM2XizlfdVvBRSmsQDWu6qc0=
 go.opentelemetry.io/contrib/instrumentation/google.golang.org/grpc/otelgrpc v0.56.0/go.mod h1:n8MR6/liuGB5EmTETUBeU5ZgqMOlqKRxUaqPQBOANZ8=
 go.opentelemetry.io/contrib/instrumentation/net/http/otelhttp v0.56.0 h1:UP6IpuHFkUgOQL9FFQFrZ+5LiwhhYRbi7VZSIx6Nj5s=
@@ -1103,8 +1107,9 @@ go.opentelemetry.io/otel v1.31.0 h1:NsJcKPIW0D0H3NgzPDHmo0WW6SptzPdqg/L1zsIm2hY=
 go.opentelemetry.io/otel v1.31.0/go.mod h1:O0C14Yl9FgkjqcCZAsE053C13OaddMYr/hz6clDkEJE=
 go.opentelemetry.io/otel/metric v1.31.0 h1:FSErL0ATQAmYHUIzSezZibnyVlft1ybhy4ozRPcF2fE=
 go.opentelemetry.io/otel/metric v1.31.0/go.mod h1:C3dEloVbLuYoX41KpmAhOqNriGbA+qqH6PQ5E5mUfnY=
-go.opentelemetry.io/otel/sdk v1.29.0 h1:vkqKjk7gwhS8VaWb0POZKmIEDimRCMsopNYnriHyryo=
-go.opentelemetry.io/otel/sdk v1.29.0/go.mod h1:pM8Dx5WKnvxLCb+8lG1PRNIDxu9g9b9g59Qr7hfAAok=
+go.opentelemetry.io/otel/sdk v1.31.0 h1:xLY3abVHYZ5HSfOg3l2E5LUj2Cwva5Y7yGxnSW9H5Gk=
+go.opentelemetry.io/otel/sdk v1.31.0/go.mod h1:TfRbMdhvxIIr/B2N2LQW2S5v9m3gOQ/08KsbbO5BPT0=
+go.opentelemetry.io/otel/sdk/metric v1.31.0/go.mod h1:CRInTMVvNhUKgSAMbKyTMxqOBC0zgyxzW55lZzX43Y8=
 go.opentelemetry.io/otel/trace v1.31.0 h1:ffjsj1aRouKewfr85U2aGagJ46+MvodynlQ1HYdmJys=
 go.opentelemetry.io/otel/trace v1.31.0/go.mod h1:TXZkRk7SM2ZQLtR6eoAWQFIHPvzQ06FJAsO1tJg480A=
 go.opentelemetry.io/proto/otlp v0.7.0/go.mod h1:PqfVotwruBrMGOCsRd/89rSnXhoiJIqeYNgFYFoEGnI=
@@ -1405,6 +1410,7 @@ golang.org/x/sys v0.17.0/go.mod h1:/VUhepiaJMQUp4+oa/7Zr1D23ma6VTLIYjOOTFZPUcA=
 golang.org/x/sys v0.18.0/go.mod h1:/VUhepiaJMQUp4+oa/7Zr1D23ma6VTLIYjOOTFZPUcA=
 golang.org/x/sys v0.20.0/go.mod h1:/VUhepiaJMQUp4+oa/7Zr1D23ma6VTLIYjOOTFZPUcA=
 golang.org/x/sys v0.21.0/go.mod h1:/VUhepiaJMQUp4+oa/7Zr1D23ma6VTLIYjOOTFZPUcA=
+golang.org/x/sys v0.22.0/go.mod h1:/VUhepiaJMQUp4+oa/7Zr1D23ma6VTLIYjOOTFZPUcA=
 golang.org/x/sys v0.23.0/go.mod h1:/VUhepiaJMQUp4+oa/7Zr1D23ma6VTLIYjOOTFZPUcA=
 golang.org/x/sys v0.24.0/go.mod h1:/VUhepiaJMQUp4+oa/7Zr1D23ma6VTLIYjOOTFZPUcA=
 golang.org/x/sys v0.25.0/go.mod h1:/VUhepiaJMQUp4+oa/7Zr1D23ma6VTLIYjOOTFZPUcA=
diff --git a/interop/xds/go.mod b/interop/xds/go.mod
index d4052ef9..d3fa9e1b 100644
--- a/interop/xds/go.mod
+++ b/interop/xds/go.mod
@@ -4,14 +4,11 @@ go 1.22.7
 
 replace google.golang.org/grpc => ../..
 
-replace google.golang.org/grpc/stats/opentelemetry => ../../stats/opentelemetry
-
 require (
 	github.com/prometheus/client_golang v1.20.5
 	go.opentelemetry.io/otel/exporters/prometheus v0.53.0
 	go.opentelemetry.io/otel/sdk/metric v1.31.0
 	google.golang.org/grpc v1.67.1
-	google.golang.org/grpc/stats/opentelemetry v0.0.0-20241017035653-830135e6c5a3
 )
 
 require (
diff --git a/resolver/resolver.go b/resolver/resolver.go
index 96294ac3..8eb1cf3b 100644
--- a/resolver/resolver.go
+++ b/resolver/resolver.go
@@ -22,6 +22,7 @@ package resolver
 
 import (
 	"context"
+	"errors"
 	"fmt"
 	"net"
 	"net/url"
@@ -330,3 +331,20 @@ type AuthorityOverrider interface {
 	// typically in line, and must keep it unchanged.
 	OverrideAuthority(Target) string
 }
+
+// ValidateEndpoints validates endpoints from a petiole policy's perspective.
+// Petiole policies should call this before calling into their children. See
+// [gRPC A61](https://github.com/grpc/proposal/blob/master/A61-IPv4-IPv6-dualstack-backends.md)
+// for details.
+func ValidateEndpoints(endpoints []Endpoint) error {
+	if len(endpoints) == 0 {
+		return errors.New("endpoints list is empty")
+	}
+
+	for _, endpoint := range endpoints {
+		for range endpoint.Addresses {
+			return nil
+		}
+	}
+	return errors.New("endpoints list contains no addresses")
+}
diff --git a/server.go b/server.go
index d1e1415a..62a5b04b 100644
--- a/server.go
+++ b/server.go
@@ -1783,17 +1783,20 @@ func (s *Server) handleStream(t transport.ServerTransport, stream *transport.Str
 	service := sm[:pos]
 	method := sm[pos+1:]
 
-	md, _ := metadata.FromIncomingContext(ctx)
-	for _, sh := range s.opts.statsHandlers {
-		ctx = sh.TagRPC(ctx, &stats.RPCTagInfo{FullMethodName: stream.Method()})
-		sh.HandleRPC(ctx, &stats.InHeader{
-			FullMethod:  stream.Method(),
-			RemoteAddr:  t.Peer().Addr,
-			LocalAddr:   t.Peer().LocalAddr,
-			Compression: stream.RecvCompress(),
-			WireLength:  stream.HeaderWireLength(),
-			Header:      md,
-		})
+	// FromIncomingContext is expensive: skip if there are no statsHandlers
+	if len(s.opts.statsHandlers) > 0 {
+		md, _ := metadata.FromIncomingContext(ctx)
+		for _, sh := range s.opts.statsHandlers {
+			ctx = sh.TagRPC(ctx, &stats.RPCTagInfo{FullMethodName: stream.Method()})
+			sh.HandleRPC(ctx, &stats.InHeader{
+				FullMethod:  stream.Method(),
+				RemoteAddr:  t.Peer().Addr,
+				LocalAddr:   t.Peer().LocalAddr,
+				Compression: stream.RecvCompress(),
+				WireLength:  stream.HeaderWireLength(),
+				Header:      md,
+			})
+		}
 	}
 	// To have calls in stream callouts work. Will delete once all stats handler
 	// calls come from the gRPC layer.
diff --git a/stats/opencensus/go.sum b/stats/opencensus/go.sum
index f545f284..447a12f3 100644
--- a/stats/opencensus/go.sum
+++ b/stats/opencensus/go.sum
@@ -213,6 +213,7 @@ cloud.google.com/go/compute/metadata v0.2.0/go.mod h1:zFmK7XCadkQkj6TtorcaGlCW1h
 cloud.google.com/go/compute/metadata v0.2.1/go.mod h1:jgHgmJd2RKBGzXqF5LR2EZMGxBkeanZ9wwa75XHJgOM=
 cloud.google.com/go/compute/metadata v0.2.3/go.mod h1:VAV5nSsACxMJvgaAuX6Pk2AawlZn8kiOGuCv6gTkwuA=
 cloud.google.com/go/compute/metadata v0.3.0/go.mod h1:zFmK7XCadkQkj6TtorcaGlCW1hT1fIilQDwofLpJ20k=
+cloud.google.com/go/compute/metadata v0.5.0/go.mod h1:aHnloV2TPI38yx4s9+wAZhHykWvVCfu7hQbF+9CWoiY=
 cloud.google.com/go/compute/metadata v0.5.2/go.mod h1:C66sj2AluDcIqakBq/M8lw8/ybHgOZqin2obFxa/E5k=
 cloud.google.com/go/contactcenterinsights v1.3.0/go.mod h1:Eu2oemoePuEFc/xKFPjbTuPSj0fYJcPls9TFlPNnHHY=
 cloud.google.com/go/contactcenterinsights v1.4.0/go.mod h1:L2YzkGbPsv+vMQMCADxJoT9YiTTnSEd6fEvCeHTYVck=
@@ -756,6 +757,7 @@ gioui.org v0.0.0-20210308172011-57750fc8a0a6/go.mod h1:RSH6KIUZ0p2xy5zHDxgAM4zum
 git.sr.ht/~sbinet/gg v0.3.1/go.mod h1:KGYtlADtqsqANL9ueOFkWymvzUvLMQllU5Ixo+8v3pc=
 github.com/BurntSushi/toml v0.3.1/go.mod h1:xHWCNGjB5oqiDr8zfno3MHue2Ht5sIBksp03qcyfWMU=
 github.com/BurntSushi/xgb v0.0.0-20160522181843-27f122750802/go.mod h1:IVnqGOEym/WlBOVXweHU+Q+/VP0lqqI8lqeDx9IjBqo=
+github.com/GoogleCloudPlatform/opentelemetry-operations-go/detectors/gcp v1.24.2/go.mod h1:itPGVDKf9cC/ov4MdvJ2QZ0khw4bfoo9jzwTJlaxy2k=
 github.com/JohnCGriffin/overflow v0.0.0-20211019200055-46fa312c352c/go.mod h1:X0CRv0ky0k6m906ixxpzmDRLvX58TFUKS2eePweuyxk=
 github.com/ajstarks/deck v0.0.0-20200831202436-30c9fc6549a9/go.mod h1:JynElWSGnm/4RlzPXRlREEwqTHAN3T56Bv2ITsFT3gY=
 github.com/ajstarks/deck/generate v0.0.0-20210309230005-c3f852c02e19/go.mod h1:T13YZdzov6OU0A1+RfKZiZN9ca6VeKdBdyDV+BY97Tk=
@@ -818,6 +820,9 @@ github.com/go-gl/glfw/v3.3/glfw v0.0.0-20191125211704-12ad95a8df72/go.mod h1:tQ2
 github.com/go-gl/glfw/v3.3/glfw v0.0.0-20200222043503-6f7a984d4dc4/go.mod h1:tQ2UAYgL5IevRw8kRxooKSPJfGvJ9fJQFa0TUsXzTg8=
 github.com/go-latex/latex v0.0.0-20210118124228-b3d85cf34e07/go.mod h1:CO1AlKB2CSIqUrmQPqA0gdRIlnLEY0gK5JGjh37zN5U=
 github.com/go-latex/latex v0.0.0-20210823091927-c0d11ff05a81/go.mod h1:SX0U8uGpxhq9o2S/CELCSUxEWWAuoCUcVCQWv7G2OCk=
+github.com/go-logr/logr v1.2.2/go.mod h1:jdQByPbusPIv2/zmleS9BjJVeZ6kBagPoEUsqbVz/1A=
+github.com/go-logr/logr v1.4.2/go.mod h1:9T104GzyrTigFIr8wt5mBrctHMim0Nb2HLGrmQ40KvY=
+github.com/go-logr/stdr v1.2.2/go.mod h1:mMo/vtBO5dYbehREoey6XUKy/eSumjCCveDpRre4VKE=
 github.com/go-pdf/fpdf v0.5.0/go.mod h1:HzcnA+A23uwogo0tp9yU+l3V+KXhiESpt1PMayhOh5M=
 github.com/go-pdf/fpdf v0.6.0/go.mod h1:HzcnA+A23uwogo0tp9yU+l3V+KXhiESpt1PMayhOh5M=
 github.com/goccy/go-json v0.9.11/go.mod h1:6MelG93GURQebXPDq3khkgXZkazVtN9CRI+MGFi0w8I=
@@ -992,6 +997,7 @@ github.com/rogpeppe/fastuuid v1.2.0/go.mod h1:jVj6XXZzXRy/MSR5jhDC/2q6DgLz+nrA6L
 github.com/rogpeppe/go-internal v1.3.0/go.mod h1:M8bDsm7K2OlrFYOpmOWEs/qY81heoFRclV5y23lUDJ4=
 github.com/rogpeppe/go-internal v1.6.1/go.mod h1:xXDCJY+GAPziupqXw64V24skbSoqbTEfhy4qGm1nDQc=
 github.com/rogpeppe/go-internal v1.9.0/go.mod h1:WtVeX8xhTBvf0smdhujwtBcq4Qrzq/fJaraNFVN+nFs=
+github.com/rogpeppe/go-internal v1.10.0/go.mod h1:UQnix2H7Ngw/k4C5ijL5+65zddjncjaFoBhdsK/akog=
 github.com/ruudk/golang-pdf417 v0.0.0-20181029194003-1af4ab5afa58/go.mod h1:6lfFZQK844Gfx8o5WFuvpxWRwnSoipWe/p622j1v06w=
 github.com/ruudk/golang-pdf417 v0.0.0-20201230142125-a7e3863a1245/go.mod h1:pQAZKsJ8yyVxGRWYNEm9oFB8ieLgKFnamEyDmSA0BRk=
 github.com/spf13/afero v1.3.3/go.mod h1:5KUK8ByomD5Ti5Artl0RtHeI5pTF7MIDuXL3yY520V4=
@@ -1030,6 +1036,12 @@ go.opencensus.io v0.22.5/go.mod h1:5pWMHQbX5EPX2/62yrJeAkowc+lfs/XD7Uxpq3pI6kk=
 go.opencensus.io v0.23.0/go.mod h1:XItmlyltB5F7CS4xOC1DcqMoFqwtC6OG2xF7mCv7P7E=
 go.opencensus.io v0.24.0 h1:y73uSU6J157QMP2kn2r30vwW1A2W2WFwSCGnAVxeaD0=
 go.opencensus.io v0.24.0/go.mod h1:vNK8G9p7aAivkbmorf4v+7Hgx+Zs0yY+0fOtgBfjQKo=
+go.opentelemetry.io/contrib/detectors/gcp v1.31.0/go.mod h1:tzQL6E1l+iV44YFTkcAeNQqzXUiekSYP9jjJjXwEd00=
+go.opentelemetry.io/otel v1.31.0/go.mod h1:O0C14Yl9FgkjqcCZAsE053C13OaddMYr/hz6clDkEJE=
+go.opentelemetry.io/otel/metric v1.31.0/go.mod h1:C3dEloVbLuYoX41KpmAhOqNriGbA+qqH6PQ5E5mUfnY=
+go.opentelemetry.io/otel/sdk v1.31.0/go.mod h1:TfRbMdhvxIIr/B2N2LQW2S5v9m3gOQ/08KsbbO5BPT0=
+go.opentelemetry.io/otel/sdk/metric v1.31.0/go.mod h1:CRInTMVvNhUKgSAMbKyTMxqOBC0zgyxzW55lZzX43Y8=
+go.opentelemetry.io/otel/trace v1.31.0/go.mod h1:TXZkRk7SM2ZQLtR6eoAWQFIHPvzQ06FJAsO1tJg480A=
 go.opentelemetry.io/proto/otlp v0.7.0/go.mod h1:PqfVotwruBrMGOCsRd/89rSnXhoiJIqeYNgFYFoEGnI=
 go.opentelemetry.io/proto/otlp v0.15.0/go.mod h1:H7XAot3MsfNsj7EXtrA2q5xSNQ10UqI405h3+duxN4U=
 go.opentelemetry.io/proto/otlp v0.19.0/go.mod h1:H7XAot3MsfNsj7EXtrA2q5xSNQ10UqI405h3+duxN4U=
@@ -1325,6 +1337,7 @@ golang.org/x/sys v0.17.0/go.mod h1:/VUhepiaJMQUp4+oa/7Zr1D23ma6VTLIYjOOTFZPUcA=
 golang.org/x/sys v0.18.0/go.mod h1:/VUhepiaJMQUp4+oa/7Zr1D23ma6VTLIYjOOTFZPUcA=
 golang.org/x/sys v0.20.0/go.mod h1:/VUhepiaJMQUp4+oa/7Zr1D23ma6VTLIYjOOTFZPUcA=
 golang.org/x/sys v0.21.0/go.mod h1:/VUhepiaJMQUp4+oa/7Zr1D23ma6VTLIYjOOTFZPUcA=
+golang.org/x/sys v0.22.0/go.mod h1:/VUhepiaJMQUp4+oa/7Zr1D23ma6VTLIYjOOTFZPUcA=
 golang.org/x/sys v0.23.0/go.mod h1:/VUhepiaJMQUp4+oa/7Zr1D23ma6VTLIYjOOTFZPUcA=
 golang.org/x/sys v0.24.0/go.mod h1:/VUhepiaJMQUp4+oa/7Zr1D23ma6VTLIYjOOTFZPUcA=
 golang.org/x/sys v0.25.0/go.mod h1:/VUhepiaJMQUp4+oa/7Zr1D23ma6VTLIYjOOTFZPUcA=
diff --git a/stats/opentelemetry/go.mod b/stats/opentelemetry/go.mod
deleted file mode 100644
index 61e31b4c..00000000
--- a/stats/opentelemetry/go.mod
+++ /dev/null
@@ -1,39 +0,0 @@
-module google.golang.org/grpc/stats/opentelemetry
-
-go 1.22.7
-
-replace google.golang.org/grpc => ../..
-
-require (
-	github.com/envoyproxy/go-control-plane v0.13.1
-	github.com/google/go-cmp v0.6.0
-	go.opentelemetry.io/contrib/detectors/gcp v1.31.0
-	go.opentelemetry.io/otel v1.31.0
-	go.opentelemetry.io/otel/metric v1.31.0
-	go.opentelemetry.io/otel/sdk v1.31.0
-	go.opentelemetry.io/otel/sdk/metric v1.31.0
-	google.golang.org/grpc v1.67.1
-	google.golang.org/protobuf v1.35.1
-)
-
-require (
-	cel.dev/expr v0.16.2 // indirect
-	cloud.google.com/go/compute/metadata v0.5.2 // indirect
-	github.com/GoogleCloudPlatform/opentelemetry-operations-go/detectors/gcp v1.24.3 // indirect
-	github.com/census-instrumentation/opencensus-proto v0.4.1 // indirect
-	github.com/cespare/xxhash/v2 v2.3.0 // indirect
-	github.com/cncf/xds/go v0.0.0-20240905190251-b4127c9b8d78 // indirect
-	github.com/envoyproxy/protoc-gen-validate v1.1.0 // indirect
-	github.com/go-logr/logr v1.4.2 // indirect
-	github.com/go-logr/stdr v1.2.2 // indirect
-	github.com/google/uuid v1.6.0 // indirect
-	github.com/planetscale/vtprotobuf v0.6.1-0.20240319094008-0393e58bdf10 // indirect
-	go.opentelemetry.io/otel/trace v1.31.0 // indirect
-	golang.org/x/net v0.30.0 // indirect
-	golang.org/x/oauth2 v0.23.0 // indirect
-	golang.org/x/sync v0.8.0 // indirect
-	golang.org/x/sys v0.26.0 // indirect
-	golang.org/x/text v0.19.0 // indirect
-	google.golang.org/genproto/googleapis/api v0.0.0-20241015192408-796eee8c2d53 // indirect
-	google.golang.org/genproto/googleapis/rpc v0.0.0-20241015192408-796eee8c2d53 // indirect
-)
diff --git a/stats/opentelemetry/go.sum b/stats/opentelemetry/go.sum
deleted file mode 100644
index b2d047c8..00000000
--- a/stats/opentelemetry/go.sum
+++ /dev/null
@@ -1,67 +0,0 @@
-cel.dev/expr v0.16.2 h1:RwRhoH17VhAu9U5CMvMhH1PDVgf0tuz9FT+24AfMLfU=
-cel.dev/expr v0.16.2/go.mod h1:gXngZQMkWJoSbE8mOzehJlXQyubn/Vg0vR9/F3W7iw8=
-cloud.google.com/go/compute/metadata v0.5.2 h1:UxK4uu/Tn+I3p2dYWTfiX4wva7aYlKixAHn3fyqngqo=
-cloud.google.com/go/compute/metadata v0.5.2/go.mod h1:C66sj2AluDcIqakBq/M8lw8/ybHgOZqin2obFxa/E5k=
-github.com/GoogleCloudPlatform/opentelemetry-operations-go/detectors/gcp v1.24.3 h1:cb3br57K508pQEFgBxn9GDhPS9HefpyMPK1RzmtMNzk=
-github.com/GoogleCloudPlatform/opentelemetry-operations-go/detectors/gcp v1.24.3/go.mod h1:itPGVDKf9cC/ov4MdvJ2QZ0khw4bfoo9jzwTJlaxy2k=
-github.com/census-instrumentation/opencensus-proto v0.4.1 h1:iKLQ0xPNFxR/2hzXZMrBo8f1j86j5WHzznCCQxV/b8g=
-github.com/census-instrumentation/opencensus-proto v0.4.1/go.mod h1:4T9NM4+4Vw91VeyqjLS6ao50K5bOcLKN6Q42XnYaRYw=
-github.com/cespare/xxhash/v2 v2.3.0 h1:UL815xU9SqsFlibzuggzjXhog7bL6oX9BbNZnL2UFvs=
-github.com/cespare/xxhash/v2 v2.3.0/go.mod h1:VGX0DQ3Q6kWi7AoAeZDth3/j3BFtOZR5XLFGgcrjCOs=
-github.com/cncf/xds/go v0.0.0-20240905190251-b4127c9b8d78 h1:QVw89YDxXxEe+l8gU8ETbOasdwEV+avkR75ZzsVV9WI=
-github.com/cncf/xds/go v0.0.0-20240905190251-b4127c9b8d78/go.mod h1:W+zGtBO5Y1IgJhy4+A9GOqVhqLpfZi+vwmdNXUehLA8=
-github.com/davecgh/go-spew v1.1.1 h1:vj9j/u1bqnvCEfJOwUhtlOARqs3+rkHYY13jYWTU97c=
-github.com/davecgh/go-spew v1.1.1/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
-github.com/envoyproxy/go-control-plane v0.13.1 h1:vPfJZCkob6yTMEgS+0TwfTUfbHjfy/6vOJ8hUWX/uXE=
-github.com/envoyproxy/go-control-plane v0.13.1/go.mod h1:X45hY0mufo6Fd0KW3rqsGvQMw58jvjymeCzBU3mWyHw=
-github.com/envoyproxy/protoc-gen-validate v1.1.0 h1:tntQDh69XqOCOZsDz0lVJQez/2L6Uu2PdjCQwWCJ3bM=
-github.com/envoyproxy/protoc-gen-validate v1.1.0/go.mod h1:sXRDRVmzEbkM7CVcM06s9shE/m23dg3wzjl0UWqJ2q4=
-github.com/go-logr/logr v1.2.2/go.mod h1:jdQByPbusPIv2/zmleS9BjJVeZ6kBagPoEUsqbVz/1A=
-github.com/go-logr/logr v1.4.2 h1:6pFjapn8bFcIbiKo3XT4j/BhANplGihG6tvd+8rYgrY=
-github.com/go-logr/logr v1.4.2/go.mod h1:9T104GzyrTigFIr8wt5mBrctHMim0Nb2HLGrmQ40KvY=
-github.com/go-logr/stdr v1.2.2 h1:hSWxHoqTgW2S2qGc0LTAI563KZ5YKYRhT3MFKZMbjag=
-github.com/go-logr/stdr v1.2.2/go.mod h1:mMo/vtBO5dYbehREoey6XUKy/eSumjCCveDpRre4VKE=
-github.com/golang/protobuf v1.5.4 h1:i7eJL8qZTpSEXOPTxNKhASYpMn+8e5Q6AdndVa1dWek=
-github.com/golang/protobuf v1.5.4/go.mod h1:lnTiLA8Wa4RWRcIUkrtSVa5nRhsEGBg48fD6rSs7xps=
-github.com/google/go-cmp v0.6.0 h1:ofyhxvXcZhMsU5ulbFiLKl/XBFqE1GSq7atu8tAmTRI=
-github.com/google/go-cmp v0.6.0/go.mod h1:17dUlkBOakJ0+DkrSSNjCkIjxS6bF9zb3elmeNGIjoY=
-github.com/google/uuid v1.6.0 h1:NIvaJDMOsjHA8n1jAhLSgzrAzy1Hgr+hNrb57e+94F0=
-github.com/google/uuid v1.6.0/go.mod h1:TIyPZe4MgqvfeYDBFedMoGGpEw/LqOeaOT+nhxU+yHo=
-github.com/planetscale/vtprotobuf v0.6.1-0.20240319094008-0393e58bdf10 h1:GFCKgmp0tecUJ0sJuv4pzYCqS9+RGSn52M3FUwPs+uo=
-github.com/planetscale/vtprotobuf v0.6.1-0.20240319094008-0393e58bdf10/go.mod h1:t/avpk3KcrXxUnYOhZhMXJlSEyie6gQbtLq5NM3loB8=
-github.com/pmezard/go-difflib v1.0.0 h1:4DBwDE0NGyQoBHbLQYPwSUPoCMWR5BEzIk/f1lZbAQM=
-github.com/pmezard/go-difflib v1.0.0/go.mod h1:iKH77koFhYxTK1pcRnkKkqfTogsbg7gZNVY4sRDYZ/4=
-github.com/stretchr/testify v1.9.0 h1:HtqpIVDClZ4nwg75+f6Lvsy/wHu+3BoSGCbBAcpTsTg=
-github.com/stretchr/testify v1.9.0/go.mod h1:r2ic/lqez/lEtzL7wO/rwa5dbSLXVDPFyf8C91i36aY=
-go.opentelemetry.io/contrib/detectors/gcp v1.31.0 h1:G1JQOreVrfhRkner+l4mrGxmfqYCAuy76asTDAo0xsA=
-go.opentelemetry.io/contrib/detectors/gcp v1.31.0/go.mod h1:tzQL6E1l+iV44YFTkcAeNQqzXUiekSYP9jjJjXwEd00=
-go.opentelemetry.io/otel v1.31.0 h1:NsJcKPIW0D0H3NgzPDHmo0WW6SptzPdqg/L1zsIm2hY=
-go.opentelemetry.io/otel v1.31.0/go.mod h1:O0C14Yl9FgkjqcCZAsE053C13OaddMYr/hz6clDkEJE=
-go.opentelemetry.io/otel/metric v1.31.0 h1:FSErL0ATQAmYHUIzSezZibnyVlft1ybhy4ozRPcF2fE=
-go.opentelemetry.io/otel/metric v1.31.0/go.mod h1:C3dEloVbLuYoX41KpmAhOqNriGbA+qqH6PQ5E5mUfnY=
-go.opentelemetry.io/otel/sdk v1.31.0 h1:xLY3abVHYZ5HSfOg3l2E5LUj2Cwva5Y7yGxnSW9H5Gk=
-go.opentelemetry.io/otel/sdk v1.31.0/go.mod h1:TfRbMdhvxIIr/B2N2LQW2S5v9m3gOQ/08KsbbO5BPT0=
-go.opentelemetry.io/otel/sdk/metric v1.31.0 h1:i9hxxLJF/9kkvfHppyLL55aW7iIJz4JjxTeYusH7zMc=
-go.opentelemetry.io/otel/sdk/metric v1.31.0/go.mod h1:CRInTMVvNhUKgSAMbKyTMxqOBC0zgyxzW55lZzX43Y8=
-go.opentelemetry.io/otel/trace v1.31.0 h1:ffjsj1aRouKewfr85U2aGagJ46+MvodynlQ1HYdmJys=
-go.opentelemetry.io/otel/trace v1.31.0/go.mod h1:TXZkRk7SM2ZQLtR6eoAWQFIHPvzQ06FJAsO1tJg480A=
-go.uber.org/goleak v1.3.0 h1:2K3zAYmnTNqV73imy9J1T3WC+gmCePx2hEGkimedGto=
-go.uber.org/goleak v1.3.0/go.mod h1:CoHD4mav9JJNrW/WLlf7HGZPjdw8EucARQHekz1X6bE=
-golang.org/x/net v0.30.0 h1:AcW1SDZMkb8IpzCdQUaIq2sP4sZ4zw+55h6ynffypl4=
-golang.org/x/net v0.30.0/go.mod h1:2wGyMJ5iFasEhkwi13ChkO/t1ECNC4X4eBKkVFyYFlU=
-golang.org/x/oauth2 v0.23.0 h1:PbgcYx2W7i4LvjJWEbf0ngHV6qJYr86PkAV3bXdLEbs=
-golang.org/x/oauth2 v0.23.0/go.mod h1:XYTD2NtWslqkgxebSiOHnXEap4TF09sJSc7H1sXbhtI=
-golang.org/x/sync v0.8.0 h1:3NFvSEYkUoMifnESzZl15y791HH1qU2xm6eCJU5ZPXQ=
-golang.org/x/sync v0.8.0/go.mod h1:Czt+wKu1gCyEFDUtn0jG5QVvpJ6rzVqr5aXyt9drQfk=
-golang.org/x/sys v0.26.0 h1:KHjCJyddX0LoSTb3J+vWpupP9p0oznkqVk/IfjymZbo=
-golang.org/x/sys v0.26.0/go.mod h1:/VUhepiaJMQUp4+oa/7Zr1D23ma6VTLIYjOOTFZPUcA=
-golang.org/x/text v0.19.0 h1:kTxAhCbGbxhK0IwgSKiMO5awPoDQ0RpfiVYBfK860YM=
-golang.org/x/text v0.19.0/go.mod h1:BuEKDfySbSR4drPmRPG/7iBdf8hvFMuRexcpahXilzY=
-google.golang.org/genproto/googleapis/api v0.0.0-20241015192408-796eee8c2d53 h1:fVoAXEKA4+yufmbdVYv+SE73+cPZbbbe8paLsHfkK+U=
-google.golang.org/genproto/googleapis/api v0.0.0-20241015192408-796eee8c2d53/go.mod h1:riSXTwQ4+nqmPGtobMFyW5FqVAmIs0St6VPp4Ug7CE4=
-google.golang.org/genproto/googleapis/rpc v0.0.0-20241015192408-796eee8c2d53 h1:X58yt85/IXCx0Y3ZwN6sEIKZzQtDEYaBWrDvErdXrRE=
-google.golang.org/genproto/googleapis/rpc v0.0.0-20241015192408-796eee8c2d53/go.mod h1:GX3210XPVPUjJbTUbvwI8f2IpZDMZuPJWDzDuebbviI=
-google.golang.org/protobuf v1.35.1 h1:m3LfL6/Ca+fqnjnlqQXNpFPABW1UD7mjh8KO2mKFytA=
-google.golang.org/protobuf v1.35.1/go.mod h1:9fA7Ob0pmnwhb644+1+CVWFRbNajQ6iRojtC/QF5bRE=
-gopkg.in/yaml.v3 v3.0.1 h1:fxVm/GzAzEWqLHuvctI91KS9hhNmmWOoWu0XTYJS7CA=
-gopkg.in/yaml.v3 v3.0.1/go.mod h1:K4uyk7z7BCEPqu6E+C64Yfv1cQ7kz7rIZviUmN+EgEM=
diff --git a/xds/internal/balancer/clustermanager/clustermanager.go b/xds/internal/balancer/clustermanager/clustermanager.go
index e6d751ec..ef5b34ea 100644
--- a/xds/internal/balancer/clustermanager/clustermanager.go
+++ b/xds/internal/balancer/clustermanager/clustermanager.go
@@ -167,11 +167,14 @@ func (b *bal) updateChildren(s balancer.ClientConnState, newConfig *lbConfig) er
 }
 
 func (b *bal) UpdateClientConnState(s balancer.ClientConnState) error {
+	if b.logger.V(2) {
+		b.logger.Infof("Received update from resolver, balancer config: %+v", pretty.ToJSON(s.BalancerConfig))
+	}
+
 	newConfig, ok := s.BalancerConfig.(*lbConfig)
 	if !ok {
 		return fmt.Errorf("unexpected balancer config with type: %T", s.BalancerConfig)
 	}
-	b.logger.Infof("Update with config %+v, resolver state %+v", pretty.ToJSON(s.BalancerConfig), s.ResolverState)
 
 	b.stateAggregator.pauseStateUpdates()
 	defer b.stateAggregator.resumeStateUpdates()
diff --git a/xds/internal/balancer/clusterresolver/clusterresolver.go b/xds/internal/balancer/clusterresolver/clusterresolver.go
index 3f0c54e8..3b996989 100644
--- a/xds/internal/balancer/clusterresolver/clusterresolver.go
+++ b/xds/internal/balancer/clusterresolver/clusterresolver.go
@@ -184,7 +184,10 @@ func (b *clusterResolverBalancer) handleClientConnUpdate(update *ccUpdate) {
 		return
 	}
 
-	b.logger.Infof("Received new balancer config: %v", pretty.ToJSON(update.state.BalancerConfig))
+	if b.logger.V(2) {
+		b.logger.Infof("Received new balancer config: %v", pretty.ToJSON(update.state.BalancerConfig))
+	}
+
 	cfg, _ := update.state.BalancerConfig.(*LBConfig)
 	if cfg == nil {
 		b.logger.Warningf("Ignoring unsupported balancer configuration of type: %T", update.state.BalancerConfig)
diff --git a/xds/internal/balancer/ringhash/ringhash.go b/xds/internal/balancer/ringhash/ringhash.go
index ef054d48..8c44f19c 100644
--- a/xds/internal/balancer/ringhash/ringhash.go
+++ b/xds/internal/balancer/ringhash/ringhash.go
@@ -285,7 +285,10 @@ func (b *ringhashBalancer) updateAddresses(addrs []resolver.Address) bool {
 }
 
 func (b *ringhashBalancer) UpdateClientConnState(s balancer.ClientConnState) error {
-	b.logger.Infof("Received update from resolver, balancer config: %+v", pretty.ToJSON(s.BalancerConfig))
+	if b.logger.V(2) {
+		b.logger.Infof("Received update from resolver, balancer config: %+v", pretty.ToJSON(s.BalancerConfig))
+	}
+
 	newConfig, ok := s.BalancerConfig.(*LBConfig)
 	if !ok {
 		return fmt.Errorf("unexpected balancer config with type: %T", s.BalancerConfig)



Test patch:
diff --git a/balancer/rls/metrics_test.go b/balancer/rls/metrics_test.go
new file mode 100644
index 00000000..ea7a9fd9
--- /dev/null
+++ b/balancer/rls/metrics_test.go
@@ -0,0 +1,367 @@
+/*
+ * 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 rls
+
+import (
+	"context"
+	"math/rand"
+	"testing"
+
+	"github.com/google/uuid"
+	"go.opentelemetry.io/otel/attribute"
+	"go.opentelemetry.io/otel/sdk/metric"
+	"go.opentelemetry.io/otel/sdk/metric/metricdata"
+	"go.opentelemetry.io/otel/sdk/metric/metricdata/metricdatatest"
+	"google.golang.org/grpc"
+	"google.golang.org/grpc/credentials/insecure"
+	rlspb "google.golang.org/grpc/internal/proto/grpc_lookup_v1"
+	"google.golang.org/grpc/internal/stubserver"
+	rlstest "google.golang.org/grpc/internal/testutils/rls"
+	testgrpc "google.golang.org/grpc/interop/grpc_testing"
+	testpb "google.golang.org/grpc/interop/grpc_testing"
+	"google.golang.org/grpc/stats/opentelemetry"
+)
+
+func metricsDataFromReader(ctx context.Context, reader *metric.ManualReader) map[string]metricdata.Metrics {
+	rm := &metricdata.ResourceMetrics{}
+	reader.Collect(ctx, rm)
+	gotMetrics := map[string]metricdata.Metrics{}
+	for _, sm := range rm.ScopeMetrics {
+		for _, m := range sm.Metrics {
+			gotMetrics[m.Name] = m
+		}
+	}
+	return gotMetrics
+}
+
+// TestRLSTargetPickMetric tests RLS Metrics in the case an RLS Balancer picks a
+// target from an RLS Response for a RPC. This should emit a
+// "grpc.lb.rls.target_picks" with certain labels and cache metrics with certain
+// labels.
+func (s) TestRLSTargetPickMetric(t *testing.T) {
+	// Overwrite the uuid random number generator to be deterministic.
+	uuid.SetRand(rand.New(rand.NewSource(1)))
+	defer uuid.SetRand(nil)
+	rlsServer, _ := rlstest.SetupFakeRLSServer(t, nil)
+	rlsConfig := buildBasicRLSConfigWithChildPolicy(t, t.Name(), rlsServer.Address)
+	backend := &stubserver.StubServer{
+		EmptyCallF: func(context.Context, *testpb.Empty) (*testpb.Empty, error) {
+			return &testpb.Empty{}, nil
+		},
+	}
+	if err := backend.StartServer(); err != nil {
+		t.Fatalf("Failed to start backend: %v", err)
+	}
+	t.Logf("Started TestService backend at: %q", backend.Address)
+	defer backend.Stop()
+
+	rlsServer.SetResponseCallback(func(context.Context, *rlspb.RouteLookupRequest) *rlstest.RouteLookupResponse {
+		return &rlstest.RouteLookupResponse{Resp: &rlspb.RouteLookupResponse{Targets: []string{backend.Address}}}
+	})
+	r := startManualResolverWithConfig(t, rlsConfig)
+	reader := metric.NewManualReader()
+	provider := metric.NewMeterProvider(metric.WithReader(reader))
+	mo := opentelemetry.MetricsOptions{
+		MeterProvider: provider,
+		Metrics:       opentelemetry.DefaultMetrics().Add("grpc.lb.rls.cache_entries", "grpc.lb.rls.cache_size", "grpc.lb.rls.default_target_picks", "grpc.lb.rls.target_picks", "grpc.lb.rls.failed_picks"),
+	}
+	grpcTarget := r.Scheme() + ":///"
+	cc, err := grpc.NewClient(grpcTarget, grpc.WithResolvers(r), grpc.WithTransportCredentials(insecure.NewCredentials()), opentelemetry.DialOption(opentelemetry.Options{MetricsOptions: mo}))
+	if err != nil {
+		t.Fatalf("Failed to dial local test server: %v", err)
+	}
+	defer cc.Close()
+
+	wantMetrics := []metricdata.Metrics{
+		{
+			Name:        "grpc.lb.rls.target_picks",
+			Description: "EXPERIMENTAL. Number of LB picks sent to each RLS target. Note that if the default target is also returned by the RLS server, RPCs sent to that target from the cache will be counted in this metric, not in grpc.rls.default_target_picks.",
+			Unit:        "pick",
+			Data: metricdata.Sum[int64]{
+				DataPoints: []metricdata.DataPoint[int64]{
+					{
+						Attributes: attribute.NewSet(attribute.String("grpc.target", grpcTarget), attribute.String("grpc.lb.rls.server_target", rlsServer.Address), attribute.String("grpc.lb.rls.data_plane_target", backend.Address), attribute.String("grpc.lb.pick_result", "complete")),
+						Value:      1,
+					},
+				},
+				Temporality: metricdata.CumulativeTemporality,
+				IsMonotonic: true,
+			},
+		},
+
+		// Receives an empty RLS Response, so a single cache entry with no size.
+		{
+			Name:        "grpc.lb.rls.cache_entries",
+			Description: "EXPERIMENTAL. Number of entries in the RLS cache.",
+			Unit:        "entry",
+			Data: metricdata.Gauge[int64]{
+				DataPoints: []metricdata.DataPoint[int64]{
+					{
+						Attributes: attribute.NewSet(attribute.String("grpc.target", grpcTarget), attribute.String("grpc.lb.rls.server_target", rlsServer.Address), attribute.String("grpc.lb.rls.instance_uuid", "52fdfc07-2182-454f-963f-5f0f9a621d72")),
+						Value:      1,
+					},
+				},
+			},
+		},
+		{
+			Name:        "grpc.lb.rls.cache_size",
+			Description: "EXPERIMENTAL. The current size of the RLS cache.",
+			Unit:        "By",
+			Data: metricdata.Gauge[int64]{
+				DataPoints: []metricdata.DataPoint[int64]{
+					{
+						Attributes: attribute.NewSet(attribute.String("grpc.target", grpcTarget), attribute.String("grpc.lb.rls.server_target", rlsServer.Address), attribute.String("grpc.lb.rls.instance_uuid", "52fdfc07-2182-454f-963f-5f0f9a621d72")),
+						Value:      35,
+					},
+				},
+			},
+		},
+	}
+	client := testgrpc.NewTestServiceClient(cc)
+	ctx, cancel := context.WithTimeout(context.Background(), defaultTestTimeout)
+	defer cancel()
+	_, err = client.EmptyCall(ctx, &testpb.Empty{})
+	if err != nil {
+		t.Fatalf("client.EmptyCall failed with error: %v", err)
+	}
+
+	gotMetrics := metricsDataFromReader(ctx, reader)
+	for _, metric := range wantMetrics {
+		val, ok := gotMetrics[metric.Name]
+		if !ok {
+			t.Fatalf("Metric %v not present in recorded metrics", metric.Name)
+		}
+		if !metricdatatest.AssertEqual(t, metric, val, metricdatatest.IgnoreTimestamp(), metricdatatest.IgnoreExemplars()) {
+			t.Fatalf("Metrics data type not equal for metric: %v", metric.Name)
+		}
+	}
+
+	// Only one pick was made, which was a target pick, so no default target
+	// pick or failed pick metric should emit.
+	for _, metric := range []string{"grpc.lb.rls.default_target_picks", "grpc.lb.rls.failed_picks"} {
+		if _, ok := gotMetrics[metric]; ok {
+			t.Fatalf("Metric %v present in recorded metrics", metric)
+		}
+	}
+}
+
+// TestRLSDefaultTargetPickMetric tests RLS Metrics in the case an RLS Balancer
+// falls back to the default target for an RPC. This should emit a
+// "grpc.lb.rls.default_target_picks" with certain labels and cache metrics with
+// certain labels.
+func (s) TestRLSDefaultTargetPickMetric(t *testing.T) {
+	// Overwrite the uuid random number generator to be deterministic.
+	uuid.SetRand(rand.New(rand.NewSource(1)))
+	defer uuid.SetRand(nil)
+
+	rlsServer, _ := rlstest.SetupFakeRLSServer(t, nil)
+	// Build RLS service config with a default target.
+	rlsConfig := buildBasicRLSConfigWithChildPolicy(t, t.Name(), rlsServer.Address)
+	backend := &stubserver.StubServer{
+		EmptyCallF: func(context.Context, *testpb.Empty) (*testpb.Empty, error) {
+			return &testpb.Empty{}, nil
+		},
+	}
+	if err := backend.StartServer(); err != nil {
+		t.Fatalf("Failed to start backend: %v", err)
+	}
+	t.Logf("Started TestService backend at: %q", backend.Address)
+	defer backend.Stop()
+	rlsConfig.RouteLookupConfig.DefaultTarget = backend.Address
+
+	r := startManualResolverWithConfig(t, rlsConfig)
+	reader := metric.NewManualReader()
+	provider := metric.NewMeterProvider(metric.WithReader(reader))
+	mo := opentelemetry.MetricsOptions{
+		MeterProvider: provider,
+		Metrics:       opentelemetry.DefaultMetrics().Add("grpc.lb.rls.cache_entries", "grpc.lb.rls.cache_size", "grpc.lb.rls.default_target_picks", "grpc.lb.rls.target_picks", "grpc.lb.rls.failed_picks"),
+	}
+	grpcTarget := r.Scheme() + ":///"
+	cc, err := grpc.NewClient(grpcTarget, grpc.WithResolvers(r), grpc.WithTransportCredentials(insecure.NewCredentials()), opentelemetry.DialOption(opentelemetry.Options{MetricsOptions: mo}))
+	if err != nil {
+		t.Fatalf("Failed to dial local test server: %v", err)
+	}
+	defer cc.Close()
+
+	wantMetrics := []metricdata.Metrics{
+		{
+			Name:        "grpc.lb.rls.default_target_picks",
+			Description: "EXPERIMENTAL. Number of LB picks sent to the default target.",
+			Unit:        "pick",
+			Data: metricdata.Sum[int64]{
+				DataPoints: []metricdata.DataPoint[int64]{
+					{
+						Attributes: attribute.NewSet(attribute.String("grpc.target", grpcTarget), attribute.String("grpc.lb.rls.server_target", rlsServer.Address), attribute.String("grpc.lb.rls.data_plane_target", backend.Address), attribute.String("grpc.lb.pick_result", "complete")),
+						Value:      1,
+					},
+				},
+				Temporality: metricdata.CumulativeTemporality,
+				IsMonotonic: true,
+			},
+		},
+		// Receives a RLS Response with target information, so a single cache
+		// entry with a certain size.
+		{
+			Name:        "grpc.lb.rls.cache_entries",
+			Description: "EXPERIMENTAL. Number of entries in the RLS cache.",
+			Unit:        "entry",
+			Data: metricdata.Gauge[int64]{
+				DataPoints: []metricdata.DataPoint[int64]{
+					{
+						Attributes: attribute.NewSet(attribute.String("grpc.target", grpcTarget), attribute.String("grpc.lb.rls.server_target", rlsServer.Address), attribute.String("grpc.lb.rls.instance_uuid", "52fdfc07-2182-454f-963f-5f0f9a621d72")),
+						Value:      1,
+					},
+				},
+			},
+		},
+		{
+			Name:        "grpc.lb.rls.cache_size",
+			Description: "EXPERIMENTAL. The current size of the RLS cache.",
+			Unit:        "By",
+			Data: metricdata.Gauge[int64]{
+				DataPoints: []metricdata.DataPoint[int64]{
+					{
+						Attributes: attribute.NewSet(attribute.String("grpc.target", grpcTarget), attribute.String("grpc.lb.rls.server_target", rlsServer.Address), attribute.String("grpc.lb.rls.instance_uuid", "52fdfc07-2182-454f-963f-5f0f9a621d72")),
+						Value:      0,
+					},
+				},
+			},
+		},
+	}
+	client := testgrpc.NewTestServiceClient(cc)
+	ctx, cancel := context.WithTimeout(context.Background(), defaultTestTimeout)
+	defer cancel()
+	if _, err = client.EmptyCall(ctx, &testpb.Empty{}); err != nil {
+		t.Fatalf("client.EmptyCall failed with error: %v", err)
+	}
+
+	gotMetrics := metricsDataFromReader(ctx, reader)
+	for _, metric := range wantMetrics {
+		val, ok := gotMetrics[metric.Name]
+		if !ok {
+			t.Fatalf("Metric %v not present in recorded metrics", metric.Name)
+		}
+		if !metricdatatest.AssertEqual(t, metric, val, metricdatatest.IgnoreTimestamp(), metricdatatest.IgnoreExemplars()) {
+			t.Fatalf("Metrics data type not equal for metric: %v", metric.Name)
+		}
+	}
+	// No target picks and failed pick metrics should be emitted, as the test
+	// made only one RPC which recorded as a default target pick.
+	for _, metric := range []string{"grpc.lb.rls.target_picks", "grpc.lb.rls.failed_picks"} {
+		if _, ok := gotMetrics[metric]; ok {
+			t.Fatalf("Metric %v present in recorded metrics", metric)
+		}
+	}
+}
+
+// TestRLSFailedRPCMetric tests RLS Metrics in the case an RLS Balancer fails an
+// RPC due to an RLS failure. This should emit a
+// "grpc.lb.rls.default_target_picks" with certain labels and cache metrics with
+// certain labels.
+func (s) TestRLSFailedRPCMetric(t *testing.T) {
+	// Overwrite the uuid random number generator to be deterministic.
+	uuid.SetRand(rand.New(rand.NewSource(1)))
+	defer uuid.SetRand(nil)
+
+	rlsServer, _ := rlstest.SetupFakeRLSServer(t, nil)
+	// Build an RLS config without a default target.
+	rlsConfig := buildBasicRLSConfigWithChildPolicy(t, t.Name(), rlsServer.Address)
+	// Register a manual resolver and push the RLS service config through it.
+	r := startManualResolverWithConfig(t, rlsConfig)
+	reader := metric.NewManualReader()
+	provider := metric.NewMeterProvider(metric.WithReader(reader))
+	mo := opentelemetry.MetricsOptions{
+		MeterProvider: provider,
+		Metrics:       opentelemetry.DefaultMetrics().Add("grpc.lb.rls.cache_entries", "grpc.lb.rls.cache_size", "grpc.lb.rls.default_target_picks", "grpc.lb.rls.target_picks", "grpc.lb.rls.failed_picks"),
+	}
+	grpcTarget := r.Scheme() + ":///"
+	cc, err := grpc.NewClient(grpcTarget, grpc.WithResolvers(r), grpc.WithTransportCredentials(insecure.NewCredentials()), opentelemetry.DialOption(opentelemetry.Options{MetricsOptions: mo}))
+	if err != nil {
+		t.Fatalf("Failed to dial local test server: %v", err)
+	}
+	defer cc.Close()
+
+	wantMetrics := []metricdata.Metrics{
+		{
+			Name:        "grpc.lb.rls.failed_picks",
+			Description: "EXPERIMENTAL. Number of LB picks failed due to either a failed RLS request or the RLS channel being throttled.",
+			Unit:        "pick",
+			Data: metricdata.Sum[int64]{
+				DataPoints: []metricdata.DataPoint[int64]{
+					{
+						Attributes: attribute.NewSet(attribute.String("grpc.target", grpcTarget), attribute.String("grpc.lb.rls.server_target", rlsServer.Address)),
+						Value:      1,
+					},
+				},
+				Temporality: metricdata.CumulativeTemporality,
+				IsMonotonic: true,
+			},
+		},
+		// Receives an empty RLS Response, so a single cache entry with no size.
+		{
+			Name:        "grpc.lb.rls.cache_entries",
+			Description: "EXPERIMENTAL. Number of entries in the RLS cache.",
+			Unit:        "entry",
+			Data: metricdata.Gauge[int64]{
+				DataPoints: []metricdata.DataPoint[int64]{
+					{
+						Attributes: attribute.NewSet(attribute.String("grpc.target", grpcTarget), attribute.String("grpc.lb.rls.server_target", rlsServer.Address), attribute.String("grpc.lb.rls.instance_uuid", "52fdfc07-2182-454f-963f-5f0f9a621d72")),
+						Value:      1,
+					},
+				},
+			},
+		},
+		{
+			Name:        "grpc.lb.rls.cache_size",
+			Description: "EXPERIMENTAL. The current size of the RLS cache.",
+			Unit:        "By",
+			Data: metricdata.Gauge[int64]{
+				DataPoints: []metricdata.DataPoint[int64]{
+					{
+						Attributes: attribute.NewSet(attribute.String("grpc.target", grpcTarget), attribute.String("grpc.lb.rls.server_target", rlsServer.Address), attribute.String("grpc.lb.rls.instance_uuid", "52fdfc07-2182-454f-963f-5f0f9a621d72")),
+						Value:      0,
+					},
+				},
+			},
+		},
+	}
+
+	ctx, cancel := context.WithTimeout(context.Background(), defaultTestTimeout)
+	defer cancel()
+	client := testgrpc.NewTestServiceClient(cc)
+	if _, err = client.EmptyCall(ctx, &testpb.Empty{}); err == nil {
+		t.Fatalf("client.EmptyCall error = %v, expected a non nil error", err)
+	}
+
+	gotMetrics := metricsDataFromReader(ctx, reader)
+	for _, metric := range wantMetrics {
+		val, ok := gotMetrics[metric.Name]
+		if !ok {
+			t.Fatalf("Metric %v not present in recorded metrics", metric.Name)
+		}
+		if !metricdatatest.AssertEqual(t, metric, val, metricdatatest.IgnoreTimestamp(), metricdatatest.IgnoreExemplars()) {
+			t.Fatalf("Metrics data type not equal for metric: %v", metric.Name)
+		}
+	}
+	// Only one RPC was made, which was a failed pick due to an RLS failure, so
+	// no metrics for target picks or default target picks should have emitted.
+	for _, metric := range []string{"grpc.lb.rls.target_picks", "grpc.lb.rls.default_target_picks"} {
+		if _, ok := gotMetrics[metric]; ok {
+			t.Fatalf("Metric %v present in recorded metrics", metric)
+		}
+	}
+}
diff --git a/credentials/google/google_test.go b/credentials/google/google_test.go
index f9353df8..7b2910a9 100644
--- a/credentials/google/google_test.go
+++ b/credentials/google/google_test.go
@@ -23,6 +23,7 @@ import (
 	"net"
 	"testing"
 
+	"github.com/google/go-cmp/cmp"
 	"google.golang.org/grpc/credentials"
 	icredentials "google.golang.org/grpc/internal/credentials"
 	"google.golang.org/grpc/internal/grpctest"
@@ -59,6 +60,18 @@ func (t *testAuthInfo) AuthType() string {
 	return t.typ
 }
 
+type testPerRPCCreds struct {
+	md map[string]string
+}
+
+func (c *testPerRPCCreds) RequireTransportSecurity() bool {
+	return true
+}
+
+func (c *testPerRPCCreds) GetRequestMetadata(context.Context, ...string) (map[string]string, error) {
+	return c.md, nil
+}
+
 var (
 	testTLS  = &testCreds{typ: "tls"}
 	testALTS = &testCreds{typ: "alts"}
@@ -161,3 +174,88 @@ func (s) TestClientHandshakeBasedOnClusterName(t *testing.T) {
 		}
 	}
 }
+
+func TestDefaultCredentialsWithOptions(t *testing.T) {
+	md1 := map[string]string{"foo": "tls"}
+	md2 := map[string]string{"foo": "alts"}
+	tests := []struct {
+		desc             string
+		defaultCredsOpts DefaultCredentialsOptions
+		authInfo         credentials.AuthInfo
+		wantedMetadata   map[string]string
+	}{
+		{
+			desc: "no ALTSPerRPCCreds with tls channel",
+			defaultCredsOpts: DefaultCredentialsOptions{
+				PerRPCCreds: &testPerRPCCreds{
+					md: md1,
+				},
+			},
+			authInfo:       &testAuthInfo{typ: "tls"},
+			wantedMetadata: md1,
+		},
+		{
+			desc: "no ALTSPerRPCCreds with alts channel",
+			defaultCredsOpts: DefaultCredentialsOptions{
+				PerRPCCreds: &testPerRPCCreds{
+					md: md1,
+				},
+			},
+			authInfo:       &testAuthInfo{typ: "alts"},
+			wantedMetadata: md1,
+		},
+		{
+			desc: "ALTSPerRPCCreds specified with tls channel",
+			defaultCredsOpts: DefaultCredentialsOptions{
+				PerRPCCreds: &testPerRPCCreds{
+					md: md1,
+				},
+				ALTSPerRPCCreds: &testPerRPCCreds{
+					md: md2,
+				},
+			},
+			authInfo:       &testAuthInfo{typ: "tls"},
+			wantedMetadata: md1,
+		},
+		{
+			desc: "ALTSPerRPCCreds specified with alts channel",
+			defaultCredsOpts: DefaultCredentialsOptions{
+				PerRPCCreds: &testPerRPCCreds{
+					md: md1,
+				},
+				ALTSPerRPCCreds: &testPerRPCCreds{
+					md: md2,
+				},
+			},
+			authInfo:       &testAuthInfo{typ: "alts"},
+			wantedMetadata: md2,
+		},
+		{
+			desc: "ALTSPerRPCCreds specified with unknown channel",
+			defaultCredsOpts: DefaultCredentialsOptions{
+				PerRPCCreds: &testPerRPCCreds{
+					md: md1,
+				},
+				ALTSPerRPCCreds: &testPerRPCCreds{
+					md: md2,
+				},
+			},
+			authInfo:       &testAuthInfo{typ: "foo"},
+			wantedMetadata: md1,
+		},
+	}
+	for _, tc := range tests {
+		t.Run(tc.desc, func(t *testing.T) {
+			bundle := NewDefaultCredentialsWithOptions(tc.defaultCredsOpts)
+			ri := credentials.RequestInfo{AuthInfo: tc.authInfo}
+			ctx := icredentials.NewRequestInfoContext(context.Background(), ri)
+			got, err := bundle.PerRPCCredentials().GetRequestMetadata(ctx, "uri")
+			if err != nil {
+				t.Fatalf("Bundle's PerRPCCredentials().GetRequestMetadata() unexpected error = %v", err)
+			}
+			if diff := cmp.Diff(got, tc.wantedMetadata); diff != "" {
+				t.Errorf("Unexpected request metadata from bundle's PerRPCCredentials. Diff (-got +want):\n%v", diff)
+			}
+		})
+	}
+}
diff --git a/resolver/resolver_test.go b/resolver/resolver_test.go
index 8d061f9b..33d2e27f 100644
--- a/resolver/resolver_test.go
+++ b/resolver/resolver_test.go
@@ -31,3 +31,75 @@ type s struct {
 func Test(t *testing.T) {
 	grpctest.RunSubTests(t, s{})
 }
+
+// TestValidateEndpoints tests different scenarios of resolver addresses being
+// validated by the ValidateEndpoint helper.
+func (s) TestValidateEndpoints(t *testing.T) {
+	addr1 := Address{Addr: "addr1"}
+	addr2 := Address{Addr: "addr2"}
+	addr3 := Address{Addr: "addr3"}
+	addr4 := Address{Addr: "addr4"}
+	tests := []struct {
+		name      string
+		endpoints []Endpoint
+		wantErr   bool
+	}{
+		{
+			name: "duplicate-address-across-endpoints",
+			endpoints: []Endpoint{
+				{Addresses: []Address{addr1}},
+				{Addresses: []Address{addr1}},
+			},
+			wantErr: false,
+		},
+		{
+			name: "duplicate-address-same-endpoint",
+			endpoints: []Endpoint{
+				{Addresses: []Address{addr1, addr1}},
+			},
+			wantErr: false,
+		},
+		{
+			name: "duplicate-address-across-endpoints-plural-addresses",
+			endpoints: []Endpoint{
+				{Addresses: []Address{addr1, addr2, addr3}},
+				{Addresses: []Address{addr3, addr4}},
+			},
+			wantErr: false,
+		},
+		{
+			name: "no-shared-addresses",
+			endpoints: []Endpoint{
+				{Addresses: []Address{addr1, addr2}},
+				{Addresses: []Address{addr3, addr4}},
+			},
+			wantErr: false,
+		},
+		{
+			name: "endpoint-with-no-addresses",
+			endpoints: []Endpoint{
+				{Addresses: []Address{addr1, addr2}},
+				{Addresses: []Address{}},
+			},
+			wantErr: false,
+		},
+		{
+			name:      "empty-endpoints-list",
+			endpoints: []Endpoint{},
+			wantErr:   true,
+		},
+		{
+			name:      "endpoint-list-with-no-addresses",
+			endpoints: []Endpoint{{}, {}},
+			wantErr:   true,
+		},
+	}
+	for _, test := range tests {
+		t.Run(test.name, func(t *testing.T) {
+			err := ValidateEndpoints(test.endpoints)
+			if (err != nil) != test.wantErr {
+				t.Fatalf("ValidateEndpoints() wantErr: %v, got: %v", test.wantErr, err)
+			}
+		})
+	}
+}
diff --git a/test/xds/xds_client_ignore_resource_deletion_test.go b/test/xds/xds_client_ignore_resource_deletion_test.go
index 6466d331..a8078cd2 100644
--- a/test/xds/xds_client_ignore_resource_deletion_test.go
+++ b/test/xds/xds_client_ignore_resource_deletion_test.go
@@ -309,12 +309,22 @@ func setupGRPCServerWithModeChangeChannelAndServe(t *testing.T, bootstrapContent
 		t.Logf("Serving mode for listener %q changed to %q, err: %v", addr.String(), args.Mode, args.Err)
 		updateCh <- args.Mode
 	})
+	stub := &stubserver.StubServer{
+		EmptyCallF: func(ctx context.Context, in *testpb.Empty) (*testpb.Empty, error) {
+			return &testpb.Empty{}, nil
+		},
+		UnaryCallF: func(ctx context.Context, in *testpb.SimpleRequest) (*testpb.SimpleResponse, error) {
+			return &testpb.SimpleResponse{}, nil
+		},
+	}
 	server, err := xds.NewGRPCServer(grpc.Creds(insecure.NewCredentials()), modeChangeOpt, xds.BootstrapContentsForTesting(bootstrapContents))
 	if err != nil {
 		t.Fatalf("Failed to create an xDS enabled gRPC server: %v", err)
 	}
 	t.Cleanup(server.Stop)
-	testgrpc.RegisterTestServiceServer(server, &testService{})
+
+	stub.S = server
+	stubserver.StartTestService(t, stub)
 
 	// Serve.
 	go func() {
diff --git a/test/xds/xds_server_certificate_providers_test.go b/test/xds/xds_server_certificate_providers_test.go
index 4fb06ce4..f277db13 100644
--- a/test/xds/xds_server_certificate_providers_test.go
+++ b/test/xds/xds_server_certificate_providers_test.go
@@ -31,6 +31,7 @@ import (
 	"google.golang.org/grpc/connectivity"
 	"google.golang.org/grpc/credentials/insecure"
 	xdscreds "google.golang.org/grpc/credentials/xds"
+	"google.golang.org/grpc/internal/stubserver"
 	"google.golang.org/grpc/internal/testutils"
 	"google.golang.org/grpc/internal/testutils/xds/e2e"
 	"google.golang.org/grpc/internal/testutils/xds/e2e/setup"
@@ -161,9 +162,12 @@ func (s) TestServerSideXDS_WithNoCertificateProvidersInBootstrap_Failure(t *test
 	if err != nil {
 		t.Fatalf("Failed to create an xDS enabled gRPC server: %v", err)
 	}
-	testgrpc.RegisterTestServiceServer(server, &testService{})
 	defer server.Stop()
 
+	stub := &stubserver.StubServer{}
+	stub.S = server
+	stubserver.StartTestService(t, stub)
+
 	// Create a local listener and pass it to Serve().
 	lis, err := testutils.LocalTCPListener()
 	if err != nil {
@@ -268,9 +272,9 @@ func (s) TestServerSideXDS_WithValidAndInvalidSecurityConfiguration(t *testing.T
 		t.Fatalf("testutils.LocalTCPListener() failed: %v", err)
 	}
 
-	// Create an xDS-enabled grpc server that is configured to use xDS
-	// credentials, and register the test service on it. Configure a mode change
-	// option that closes a channel when listener2 enter serving mode.
+	// Create an xDS-enabled gRPC server that is configured to use xDS
+	// credentials and assigned to a stub server, configuring a mode change
+	// option that closes a channel when listener2 enters serving mode.
 	creds, err := xdscreds.NewServerCredentials(xdscreds.ServerOptions{FallbackCreds: insecure.NewCredentials()})
 	if err != nil {
 		t.Fatal(err)
@@ -283,13 +287,21 @@ func (s) TestServerSideXDS_WithValidAndInvalidSecurityConfiguration(t *testing.T
 			}
 		}
 	})
+
+	stub := &stubserver.StubServer{
+		EmptyCallF: func(ctx context.Context, in *testpb.Empty) (*testpb.Empty, error) {
+			return &testpb.Empty{}, nil
+		},
+	}
 	server, err := xds.NewGRPCServer(grpc.Creds(creds), modeChangeOpt, xds.BootstrapContentsForTesting(bootstrapContents))
 	if err != nil {
 		t.Fatalf("Failed to create an xDS enabled gRPC server: %v", err)
 	}
-	testgrpc.RegisterTestServiceServer(server, &testService{})
 	defer server.Stop()
 
+	stub.S = server
+	stubserver.StartTestService(t, stub)
+
 	go func() {
 		if err := server.Serve(lis1); err != nil {
 			t.Errorf("Serve() failed: %v", err)
diff --git a/test/xds/xds_server_integration_test.go b/test/xds/xds_server_integration_test.go
index 347f069c..eacc6463 100644
--- a/test/xds/xds_server_integration_test.go
+++ b/test/xds/xds_server_integration_test.go
@@ -34,6 +34,7 @@ import (
 	xdscreds "google.golang.org/grpc/credentials/xds"
 	"google.golang.org/grpc/internal"
 	"google.golang.org/grpc/internal/grpcsync"
+	"google.golang.org/grpc/internal/stubserver"
 	"google.golang.org/grpc/internal/testutils"
 	"google.golang.org/grpc/internal/testutils/xds/e2e"
 	"google.golang.org/grpc/internal/testutils/xds/e2e/setup"
@@ -45,27 +46,6 @@ import (
 	testpb "google.golang.org/grpc/interop/grpc_testing"
 )
 
-type testService struct {
-	testgrpc.TestServiceServer
-}
-
-func (*testService) EmptyCall(context.Context, *testpb.Empty) (*testpb.Empty, error) {
-	return &testpb.Empty{}, nil
-}
-
-func (*testService) UnaryCall(context.Context, *testpb.SimpleRequest) (*testpb.SimpleResponse, error) {
-	return &testpb.SimpleResponse{}, nil
-}
-
-func (*testService) FullDuplexCall(stream testgrpc.TestService_FullDuplexCallServer) error {
-	for {
-		_, err := stream.Recv() // hangs here forever if stream doesn't shut down...doesn't receive EOF without any errors
-		if err == io.EOF {
-			return nil
-		}
-	}
-}
-
 func testModeChangeServerOption(t *testing.T) grpc.ServerOption {
 	// Create a server option to get notified about serving mode changes. We don't
 	// do anything other than throwing a log entry here. But this is required,
@@ -112,12 +92,32 @@ func setupGRPCServer(t *testing.T, bootstrapContents []byte) (net.Listener, func
 		t.Fatal(err)
 	}
 
-	// Initialize an xDS-enabled gRPC server and register the stubServer on it.
+	// Initialize a test gRPC server, assign it to the stub server, and start
+	// the test service.
+	stub := &stubserver.StubServer{
+		EmptyCallF: func(ctx context.Context, in *testpb.Empty) (*testpb.Empty, error) {
+			return &testpb.Empty{}, nil
+		},
+		UnaryCallF: func(ctx context.Context, in *testpb.SimpleRequest) (*testpb.SimpleResponse, error) {
+			return &testpb.SimpleResponse{}, nil
+		},
+		FullDuplexCallF: func(stream testgrpc.TestService_FullDuplexCallServer) error {
+			for {
+				_, err := stream.Recv() // hangs here forever if stream doesn't shut down...doesn't receive EOF without any errors
+				if err == io.EOF {
+					return nil
+				}
+			}
+		},
+	}
+
 	server, err := xds.NewGRPCServer(grpc.Creds(creds), testModeChangeServerOption(t), xds.BootstrapContentsForTesting(bootstrapContents))
 	if err != nil {
 		t.Fatalf("Failed to create an xDS enabled gRPC server: %v", err)
 	}
-	testgrpc.RegisterTestServiceServer(server, &testService{})
+
+	stub.S = server
+	stubserver.StartTestService(t, stub)
 
 	// Create a local listener and pass it to Serve().
 	lis, err := testutils.LocalTCPListener()
diff --git a/test/xds/xds_server_serving_mode_test.go b/test/xds/xds_server_serving_mode_test.go
index 40bc1f68..3ed6750a 100644
--- a/test/xds/xds_server_serving_mode_test.go
+++ b/test/xds/xds_server_serving_mode_test.go
@@ -29,6 +29,7 @@ import (
 	"google.golang.org/grpc/connectivity"
 	"google.golang.org/grpc/credentials/insecure"
 	xdscreds "google.golang.org/grpc/credentials/xds"
+	"google.golang.org/grpc/internal/stubserver"
 	"google.golang.org/grpc/internal/testutils"
 	"google.golang.org/grpc/internal/testutils/xds/e2e"
 	"google.golang.org/grpc/internal/testutils/xds/e2e/setup"
@@ -62,13 +63,21 @@ func (s) TestServerSideXDS_RedundantUpdateSuppression(t *testing.T) {
 		updateCh <- args.Mode
 	})
 
-	// Initialize an xDS-enabled gRPC server and register the stubServer on it.
+	// Initialize a test gRPC server, assign it to the stub server, and start
+	// the test service.
+	stub := &stubserver.StubServer{
+		EmptyCallF: func(ctx context.Context, in *testpb.Empty) (*testpb.Empty, error) {
+			return &testpb.Empty{}, nil
+		},
+	}
 	server, err := xds.NewGRPCServer(grpc.Creds(creds), modeChangeOpt, xds.BootstrapContentsForTesting(bootstrapContents))
 	if err != nil {
 		t.Fatalf("Failed to create an xDS enabled gRPC server: %v", err)
 	}
 	defer server.Stop()
-	testgrpc.RegisterTestServiceServer(server, &testService{})
+
+	stub.S = server
+	stubserver.StartTestService(t, stub)
 
 	// Setup the management server to respond with the listener resources.
 	host, port, err := hostPortFromListener(lis)
@@ -206,13 +215,21 @@ func (s) TestServerSideXDS_ServingModeChanges(t *testing.T) {
 		}
 	})
 
-	// Initialize an xDS-enabled gRPC server and register the stubServer on it.
+	// Initialize a test gRPC server, assign it to the stub server, and start
+	// the test service.
+	stub := &stubserver.StubServer{
+		EmptyCallF: func(ctx context.Context, in *testpb.Empty) (*testpb.Empty, error) {
+			return &testpb.Empty{}, nil
+		},
+	}
 	server, err := xds.NewGRPCServer(grpc.Creds(creds), modeChangeOpt, xds.BootstrapContentsForTesting(bootstrapContents))
 	if err != nil {
 		t.Fatalf("Failed to create an xDS enabled gRPC server: %v", err)
 	}
 	defer server.Stop()
-	testgrpc.RegisterTestServiceServer(server, &testService{})
+
+	stub.S = server
+	stubserver.StartTestService(t, stub)
 
 	// Setup the management server to respond with server-side Listener
 	// resources for both listeners.
diff --git a/test/xds/xds_server_test.go b/test/xds/xds_server_test.go
index 3ede7af3..6912757e 100644
--- a/test/xds/xds_server_test.go
+++ b/test/xds/xds_server_test.go
@@ -31,6 +31,7 @@ import (
 	"google.golang.org/grpc/connectivity"
 	"google.golang.org/grpc/credentials/insecure"
 	"google.golang.org/grpc/internal/grpcsync"
+	"google.golang.org/grpc/internal/stubserver"
 	"google.golang.org/grpc/internal/testutils"
 	"google.golang.org/grpc/internal/testutils/xds/e2e"
 	"google.golang.org/grpc/internal/testutils/xds/e2e/setup"
@@ -93,12 +94,20 @@ func (s) TestServeLDSRDS(t *testing.T) {
 		}
 	})
 
+	stub := &stubserver.StubServer{
+		EmptyCallF: func(ctx context.Context, in *testpb.Empty) (*testpb.Empty, error) {
+			return &testpb.Empty{}, nil
+		},
+	}
 	server, err := xds.NewGRPCServer(grpc.Creds(insecure.NewCredentials()), modeChangeOpt, xds.BootstrapContentsForTesting(bootstrapContents))
 	if err != nil {
 		t.Fatalf("Failed to create an xDS enabled gRPC server: %v", err)
 	}
 	defer server.Stop()
-	testgrpc.RegisterTestServiceServer(server, &testService{})
+
+	stub.S = server
+	stubserver.StartTestService(t, stub)
+
 	go func() {
 		if err := server.Serve(lis); err != nil {
 			t.Errorf("Serve() failed: %v", err)
@@ -201,12 +210,20 @@ func (s) TestRDSNack(t *testing.T) {
 		}
 	})
 
+	stub := &stubserver.StubServer{
+		EmptyCallF: func(ctx context.Context, in *testpb.Empty) (*testpb.Empty, error) {
+			return &testpb.Empty{}, nil
+		},
+	}
 	server, err := xds.NewGRPCServer(grpc.Creds(insecure.NewCredentials()), modeChangeOpt, xds.BootstrapContentsForTesting(bootstrapContents))
 	if err != nil {
 		t.Fatalf("Failed to create an xDS enabled gRPC server: %v", err)
 	}
 	defer server.Stop()
-	testgrpc.RegisterTestServiceServer(server, &testService{})
+
+	stub.S = server
+	stubserver.StartTestService(t, stub)
+
 	go func() {
 		if err := server.Serve(lis); err != nil {
 			t.Errorf("Serve() failed: %v", err)
@@ -259,12 +276,30 @@ func (s) TestMultipleUpdatesImmediatelySwitch(t *testing.T) {
 	if err := managementServer.Update(ctx, resources); err != nil {
 		t.Fatal(err)
 	}
+
+	stub := &stubserver.StubServer{
+		EmptyCallF: func(ctx context.Context, in *testpb.Empty) (*testpb.Empty, error) {
+			return &testpb.Empty{}, nil
+		},
+		FullDuplexCallF: func(stream testgrpc.TestService_FullDuplexCallServer) error {
+			for {
+				_, err := stream.Recv() // hangs here forever if stream doesn't shut down...doesn't receive EOF without any errors
+				if err == io.EOF {
+					return nil
+				}
+			}
+		},
+	}
+
 	server, err := xds.NewGRPCServer(grpc.Creds(insecure.NewCredentials()), testModeChangeServerOption(t), xds.BootstrapContentsForTesting(bootstrapContents))
 	if err != nil {
 		t.Fatalf("Failed to create an xDS enabled gRPC server: %v", err)
 	}
 	defer server.Stop()
-	testgrpc.RegisterTestServiceServer(server, &testService{})
+
+	stub.S = server
+	stubserver.StartTestService(t, stub)
+
 	go func() {
 		if err := server.Serve(lis); err != nil {
 			t.Errorf("Serve() failed: %v", err)