grpc/grpc-go · error

extproc: empty grpc_service provided in config

Error message

extproc: empty grpc_service provided in config %v

What it means

Returned by ParseFilterConfig when the decoded ExternalProcessor message has a nil grpc_service field. The grpc_service tells the client where the external processor server lives (target URI, credentials); without it the filter cannot connect to a processor. Hit at ext_proc.go:125.

Solutions

1. Populate grpc_service with a valid envoy.config.core.v3.GrpcService (at least a target URI).
2. Use the google_grpc or envoy_grpc variant as appropriate for your environment.
3. Add schema validation in the control plane requiring grpc_service for ext_proc filters.
4. Diff the resource against a known-good ext_proc config.

Example fix

# before
# ExternalProcessor with grpc_service omitted
# after
grpc_service:
  envoy_grpc:
    cluster_name: ext-proc-cluster

// control-plane guard
if cfg.GetGrpcService() == nil {
  return fmt.Errorf("ext_proc config requires grpc_service")
}

When it happens

Trigger: An xDS ExternalProcessor resource is sent without grpc_service populated. ParseFilterConfig checks msg.GetGrpcService() == nil and rejects the config.

Common situations: The grpc_service was templated from a variable that resolved empty; a config author relied on a non-existent default; the field was dropped during a proto refactor.

Related errors

• extproc: missing processing_mode in config
• external processor sent an immediate response but immediate…
• extproc: error parsing config
• extproc: error parsing override
• extproc: failed to parse grpc_service

AI-assisted analysis of grpc/grpc-go@0c51461d27 (2026-08-11). Data as JSON: /api/errors/294cd0801a466108. Report an issue: GitHub.

Appendix: source

Thrown at internal/xds/httpfilter/extproc/ext_proc.go:126

func (builder) ParseFilterConfig(cfg proto.Message) (httpfilter.FilterConfig, error) {
	m, ok := cfg.(*anypb.Any)
	if !ok {
		return nil, fmt.Errorf("extproc: error parsing config %v: unknown type %T, want *anypb.Any", cfg, cfg)
	}
	msg := new(v3procfilterpb.ExternalProcessor)
	if err := m.UnmarshalTo(msg); err != nil {
		return nil, fmt.Errorf("extproc: failed to unmarshal config %v: %v", cfg, err)
	}
	if msg.GetProcessingMode() == nil {
		return nil, fmt.Errorf("extproc: missing processing_mode in config %v", cfg)
	}
	if err := validateBodyProcessingMode(msg.GetProcessingMode()); err != nil {
		return nil, err
	}

	if msg.GetGrpcService() == nil {
		return nil, fmt.Errorf("extproc: empty grpc_service provided in config %v", cfg)
	}
	server, err := iextproc.ParseGRPCServiceConfig(msg.GetGrpcService())
	if err != nil {
		return nil, fmt.Errorf("extproc: failed to parse grpc_service %v", err)
	}

	mutationRules, err := httpfilter.HeaderMutationRulesFromProto(msg.GetMutationRules())
	if err != nil {
		return nil, err
	}

	var allowedHeaders, disallowedHeaders []matcher.StringMatcher
	if allowed := msg.GetForwardRules().GetAllowedHeaders(); allowed != nil {
		allowedHeaders, err = httpfilter.ConvertStringMatchers(allowed.GetPatterns())
		if err != nil {
			return nil, err
		}
	}

View on GitHub (pinned to 0c51461d27)