make the RLS LB policy name available in the internal package (#5259)

balancer/rls/balancer.go

@@ -30,6 +30,7 @@ import (
 	"google.golang.org/grpc/balancer"
 	"google.golang.org/grpc/connectivity"
 	"google.golang.org/grpc/grpclog"
+	"google.golang.org/grpc/internal"
 	"google.golang.org/grpc/internal/backoff"
 	"google.golang.org/grpc/internal/balancergroup"
 	"google.golang.org/grpc/internal/buffer"
@@ -40,7 +41,10 @@ import (
 
 const (
 	// Name is the name of the RLS LB policy.
-	Name = "rls_experimental"
+	//
+	// It currently has an experimental suffix which would be removed once
+	// end-to-end testing of the policy is completed.
+	Name = internal.RLSLoadBalancingPolicyName
 	// Default frequency for data cache purging.
 	periodicCachePurgeFreq = time.Minute
 )

internal/internal.go

@@ -85,3 +85,9 @@ const (
 	// that supports backend returned by grpclb balancer.
 	CredsBundleModeBackendFromBalancer = "backend-from-balancer"
 )
+
+// RLSLoadBalancingPolicyName is the name of the RLS LB policy.
+//
+// It currently has an experimental suffix which would be removed once
+// end-to-end testing of the policy is completed.
+const RLSLoadBalancingPolicyName = "rls_experimental"

xds/internal/clusterspecifier/rls/rls.go

@@ -26,14 +26,12 @@ import (
 	"github.com/golang/protobuf/proto"
 	"github.com/golang/protobuf/ptypes"
 	"google.golang.org/grpc/balancer"
+	"google.golang.org/grpc/internal"
 	"google.golang.org/grpc/internal/envconfig"
 	rlspb "google.golang.org/grpc/internal/proto/grpc_lookup_v1"
 	"google.golang.org/grpc/xds/internal/clusterspecifier"
 	"google.golang.org/protobuf/encoding/protojson"
 	"google.golang.org/protobuf/types/known/anypb"
-
-	// Never remove this import as the RLS LB policy is registered in its init().
-	rlslb "google.golang.org/grpc/balancer/rls"
 )
 
 func init() {
@@ -89,14 +87,13 @@ func (rls) ParseClusterSpecifierConfig(cfg proto.Message) (clusterspecifier.Bala
 		return nil, fmt.Errorf("rls_csp: error marshaling load balancing config %v: %v", lbCfgJSON, err)
 	}
 
-	rlsBB := balancer.Get(rlslb.Name)
+	rlsBB := balancer.Get(internal.RLSLoadBalancingPolicyName)
 	if rlsBB == nil {
 		return nil, fmt.Errorf("RLS LB policy not registered")
 	}
-	_, err = rlsBB.(balancer.ConfigParser).ParseConfig(rawJSON)
-	if err != nil {
+	if _, err = rlsBB.(balancer.ConfigParser).ParseConfig(rawJSON); err != nil {
 		return nil, fmt.Errorf("rls_csp: validation error from rls lb policy parsing %v", err)
 	}
 
-	return clusterspecifier.BalancerConfig{{rlslb.Name: lbCfgJSON}}, nil
+	return clusterspecifier.BalancerConfig{{internal.RLSLoadBalancingPolicyName: lbCfgJSON}}, nil
 }

xds/internal/clusterspecifier/rls/rls_test.go

@@ -25,13 +25,14 @@ import (
 	"github.com/golang/protobuf/proto"
 	"github.com/google/go-cmp/cmp"
 	"github.com/google/go-cmp/cmp/cmpopts"
-	_ "google.golang.org/grpc/balancer/rls"
 	"google.golang.org/grpc/internal/grpctest"
 	rlspb "google.golang.org/grpc/internal/proto/grpc_lookup_v1"
 	"google.golang.org/grpc/internal/testutils"
-	_ "google.golang.org/grpc/xds/internal/balancer/cdsbalancer"
 	"google.golang.org/grpc/xds/internal/clusterspecifier"
 	"google.golang.org/protobuf/types/known/durationpb"
+
+	_ "google.golang.org/grpc/balancer/rls"                      // Register the RLS LB policy.
+	_ "google.golang.org/grpc/xds/internal/balancer/cdsbalancer" // Register the CDS LB policy.
 )
 
 func init() {

xds/xds.go

@@ -38,6 +38,7 @@ import (
 
 	_ "google.golang.org/grpc/credentials/tls/certprovider/pemfile"         // Register the file watcher certificate provider plugin.
 	_ "google.golang.org/grpc/xds/internal/balancer"                        // Register the balancers.
+	_ "google.golang.org/grpc/xds/internal/clusterspecifier/rls"            // Register the RLS cluster specifier plugin. Note that this does not register the RLS LB policy.
 	_ "google.golang.org/grpc/xds/internal/httpfilter/fault"                // Register the fault injection filter.
 	_ "google.golang.org/grpc/xds/internal/httpfilter/rbac"                 // Register the RBAC filter.
 	_ "google.golang.org/grpc/xds/internal/httpfilter/router"               // Register the router filter.