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

internal/xds/clusterspecifier/rls/rls.go

@@ -0,0 +1,95 @@
+/*
+ *
+ * Copyright 2021 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 implements the RLS cluster specifier plugin.
+package rls
+
+import (
+	"encoding/json"
+	"fmt"
+
+	"google.golang.org/grpc/balancer"
+	"google.golang.org/grpc/internal"
+	rlspb "google.golang.org/grpc/internal/proto/grpc_lookup_v1"
+	"google.golang.org/grpc/internal/xds/clusterspecifier"
+	"google.golang.org/protobuf/encoding/protojson"
+	"google.golang.org/protobuf/proto"
+	"google.golang.org/protobuf/types/known/anypb"
+)
+
+func init() {
+	clusterspecifier.Register(rls{})
+}
+
+type rls struct{}
+
+func (rls) TypeURLs() []string {
+	return []string{"type.googleapis.com/grpc.lookup.v1.RouteLookupClusterSpecifier"}
+}
+
+// lbConfigJSON is the RLS LB Policies configuration in JSON format.
+// RouteLookupConfig will be a raw JSON string from the passed in proto
+// configuration, and the other fields will be hardcoded.
+type lbConfigJSON struct {
+	RouteLookupConfig                json.RawMessage              `json:"routeLookupConfig"`
+	ChildPolicy                      []map[string]json.RawMessage `json:"childPolicy"`
+	ChildPolicyConfigTargetFieldName string                       `json:"childPolicyConfigTargetFieldName"`
+}
+
+func (rls) ParseClusterSpecifierConfig(cfg proto.Message) (clusterspecifier.BalancerConfig, error) {
+	if cfg == nil {
+		return nil, fmt.Errorf("rls_csp: nil configuration message provided")
+	}
+	m, ok := cfg.(*anypb.Any)
+	if !ok {
+		return nil, fmt.Errorf("rls_csp: error parsing config %v: unknown type %T", cfg, cfg)
+	}
+	rlcs := new(rlspb.RouteLookupClusterSpecifier)
+
+	if err := m.UnmarshalTo(rlcs); err != nil {
+		return nil, fmt.Errorf("rls_csp: error parsing config %v: %v", cfg, err)
+	}
+	rlcJSON, err := protojson.Marshal(rlcs.GetRouteLookupConfig())
+	if err != nil {
+		return nil, fmt.Errorf("rls_csp: error marshaling route lookup config: %v: %v", rlcs.GetRouteLookupConfig(), err)
+	}
+	lbCfgJSON := &lbConfigJSON{
+		RouteLookupConfig: rlcJSON, // "JSON form of RouteLookupClusterSpecifier.config" - RLS in xDS Design Doc
+		ChildPolicy: []map[string]json.RawMessage{
+			{
+				"cds_experimental": json.RawMessage(`{"isDynamic":true}`),
+			},
+		},
+		ChildPolicyConfigTargetFieldName: "cluster",
+	}
+
+	rawJSON, err := json.Marshal(lbCfgJSON)
+	if err != nil {
+		return nil, fmt.Errorf("rls_csp: error marshaling load balancing config %v: %v", lbCfgJSON, err)
+	}
+
+	rlsBB := balancer.Get(internal.RLSLoadBalancingPolicyName)
+	if rlsBB == nil {
+		return nil, fmt.Errorf("RLS LB policy not registered")
+	}
+	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{{internal.RLSLoadBalancingPolicyName: lbCfgJSON}}, nil
+}