Use Unix sockets for gRPC in mini mode (#8856)

* Use Unix sockets for gRPC between co-located services in mini mode

In `weed mini`, all services run in one process. Previously, inter-service
gRPC traffic (volume↔master, filer↔master, S3↔filer, worker↔admin, etc.)
went through TCP loopback. This adds a gRPC Unix socket registry in the pb
package: mini mode registers a socket path per gRPC port at startup, each
gRPC server additionally listens on its socket, and GrpcDial transparently
routes to the socket via WithContextDialer when a match is found.

Standalone commands (weed master, weed filer, etc.) are unaffected since
no sockets are registered. TCP listeners are kept for external clients.

* Handle Serve error and clean up socket file in ServeGrpcOnLocalSocket

Log non-expected errors from grpcServer.Serve (ignoring
grpc.ErrServerStopped) and always remove the Unix socket file
when Serve returns, ensuring cleanup on Stop/GracefulStop.

weed/command/filer.go

@@ -421,6 +421,7 @@ func (fo *FilerOptions) startFiler() {
 		go grpcS.Serve(grpcLocalL)
 	}
 	go grpcS.Serve(grpcL)
+	pb.ServeGrpcOnLocalSocket(grpcS, grpcPort)
 
 	if runtime.GOOS != "windows" {
 		localSocket := *fo.localSocket

weed/command/master.go

@@ -254,6 +254,7 @@ func startMaster(masterOption MasterOptions, masterWhiteList []string) {
 		go grpcS.Serve(grpcLocalL)
 	}
 	go grpcS.Serve(grpcL)
+	pb.ServeGrpcOnLocalSocket(grpcS, grpcPort)
 
 	// For multi-master mode with non-Hashicorp raft, wait and check if we should join
 	if !*masterOption.raftHashicorp && !isSingleMaster {

weed/command/mini.go

@@ -823,6 +823,16 @@ func runMini(cmd *Command, args []string) bool {
 	miniS3Options.filer = &filerAddress
 	miniWebDavOptions.filer = &filerAddress
 
+	// Register Unix socket paths for gRPC services so local inter-service
+	// communication goes through Unix sockets instead of TCP.
+	pb.RegisterLocalGrpcSocket(*miniMasterOptions.portGrpc, fmt.Sprintf("/tmp/seaweedfs-master-grpc-%d.sock", *miniMasterOptions.portGrpc))
+	pb.RegisterLocalGrpcSocket(*miniOptions.v.portGrpc, fmt.Sprintf("/tmp/seaweedfs-volume-grpc-%d.sock", *miniOptions.v.portGrpc))
+	pb.RegisterLocalGrpcSocket(*miniFilerOptions.portGrpc, fmt.Sprintf("/tmp/seaweedfs-filer-grpc-%d.sock", *miniFilerOptions.portGrpc))
+	if *miniS3Options.portGrpc > 0 {
+		pb.RegisterLocalGrpcSocket(*miniS3Options.portGrpc, fmt.Sprintf("/tmp/seaweedfs-s3-grpc-%d.sock", *miniS3Options.portGrpc))
+	}
+	pb.RegisterLocalGrpcSocket(*miniAdminOptions.grpcPort, fmt.Sprintf("/tmp/seaweedfs-admin-grpc-%d.sock", *miniAdminOptions.grpcPort))
+
 	go stats_collect.StartMetricsServer(*miniMetricsHttpIp, *miniMetricsHttpPort)
 
 	if *miniMasterOptions.volumeSizeLimitMB > util.VolumeSizeLimitGB*1000 {

weed/command/s3.go

@@ -376,6 +376,7 @@ func (s3opt *S3Options) startS3Server() bool {
 		go grpcS.Serve(grpcLocalL)
 	}
 	go grpcS.Serve(grpcL)
+	pb.ServeGrpcOnLocalSocket(grpcS, grpcPort)
 
 	if *s3opt.tlsPrivateKey != "" {
 		// Check for port conflict when both HTTP and HTTPS are enabled on the same port

weed/command/volume.go

@@ -415,6 +415,7 @@ func (v VolumeServerOptions) startGrpcService(vs volume_server_pb.VolumeServerSe
 			glog.Fatalf("start gRPC service failed, %s", err)
 		}
 	}()
+	pb.ServeGrpcOnLocalSocket(grpcS, grpcPort)
 	return grpcS
 }