grpc/grpc-go · error

rls_csp: error parsing config

Error message

rls_csp: error parsing config %v: unknown type %T

What it means

ParseClusterSpecifierConfig expected the configuration wrapped as *anypb.Any but received a different concrete proto type (rls.go:58-60). In the xDS protocol all filter and extension configs are transported as Any-wrapped messages, so receiving a bare proto indicates an integration or protocol-layer error.

Solutions

1. Ensure the clusterspecifier framework passes *anypb.Any to ParseClusterSpecifierConfig
2. Do not manually unwrap Any before calling the parser
3. If writing test code, wrap the proto with anypb.New() first

Example fix

// before — passing bare proto
rlsCfg := &rlspb.RouteLookupClusterSpecifier{...}
result, err := rls{}.ParseClusterSpecifierConfig(rlsCfg)

// after — wrap in Any first
anyCfg, _ := anypb.New(rlsCfg)
result, err := rls{}.ParseClusterSpecifierConfig(anyCfg)

// Ensure the config is *anypb.Any before passing to the parser.
func isAnyProto(msg proto.Message) bool {
    _, ok := msg.(*anypb.Any)
    return ok
}

When it happens

Trigger: The clusterspecifier framework dispatches to ParseClusterSpecifierConfig with a proto.Message whose concrete type is not *anypb.Any (e.g. an already-unwrapped RouteLookupClusterSpecifier passed by custom integration or test code).

Common situations: Custom clusterspecifier integration that unwraps Any before dispatching to the plugin; incorrect framework wiring; test code passing a bare proto instead of wrapping it in anypb.New().

Related errors

• rls_csp: error marshaling load balancing config
• rls_csp: error marshaling route lookup config
• rls_csp: error parsing config
• rls_csp: nil configuration message provided
• rls_csp: validation error from rls lb policy parsing

AI-assisted analysis of grpc/grpc-go@0c51461d27 (2026-08-11). Data as JSON: /api/errors/df2b7e46195eb861. Report an issue: GitHub.

Appendix: source

Thrown at internal/xds/clusterspecifier/rls/rls.go:60

	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",

View on GitHub (pinned to 0c51461d27)