Add cluster.raft.leader.transfer command for graceful leader change (#7819)

* proto: add RaftLeadershipTransfer RPC for forced leader change

Add new gRPC RPC and messages for leadership transfer:
- RaftLeadershipTransferRequest: optional target_id and target_address
- RaftLeadershipTransferResponse: previous_leader and new_leader

This enables graceful leadership transfer before master maintenance,
reducing errors in filers during planned maintenance windows.

Ref: https://github.com/seaweedfs/seaweedfs/issues/7527

* proto: regenerate Go files for RaftLeadershipTransfer

Generated from master.proto changes.

* master: implement RaftLeadershipTransfer gRPC handler

Add gRPC handler for leadership transfer with support for:
- Transfer to any eligible follower (when target_id is empty)
- Transfer to a specific server (when target_id and target_address are provided)

Uses hashicorp/raft LeadershipTransfer() and LeadershipTransferToServer() APIs.

Returns the previous and new leader in the response.

* shell: add cluster.raft.leader.transfer command

Add weed shell command for graceful leadership transfer:
- Displays current cluster status before transfer
- Supports auto-selection of target (any eligible follower)
- Supports targeted transfer with -id and -address flags
- Provides clear feedback on success/failure with troubleshooting tips

Usage:
  cluster.raft.leader.transfer
  cluster.raft.leader.transfer -id <server_id> -address <grpc_address>

* master: add unit tests for raft gRPC handlers

Add tests covering:
- RaftLeadershipTransfer with no raft initialized
- RaftLeadershipTransfer with target_id but no address
- RaftListClusterServers with no raft initialized
- RaftAddServer with no raft initialized
- RaftRemoveServer with no raft initialized

These tests verify error handling when raft is not configured.

* shell: add tests for cluster.raft.leader.transfer command

Add tests covering:
- Command name and help text validation
- HasTag returns false for ResourceHeavy
- Validation of -id without -address
- Argument parsing with unknown flags

* master: clarify that leadership transfer requires -raftHashicorp

The default raft implementation (seaweedfs/raft, a goraft fork) does not
support graceful leadership transfer. This feature is only available when
using hashicorp raft (-raftHashicorp=true).

Update error messages and help text to make this requirement clear:
- gRPC handler returns specific error for goraft users
- Shell command help text notes the requirement
- Added test for goraft case

* test: use strings.Contains instead of custom helper

Replace custom contains/containsHelper functions with the standard
library strings.Contains for better maintainability.

* shell: return flag parsing errors instead of swallowing them

- Return the error from flag.Parse() instead of returning nil
- Update test to explicitly assert error for unknown flags

* test: document integration test scenarios for Raft leadership transfer

Add comments explaining:
- Why these unit tests only cover 'Raft not initialized' scenarios
- What integration tests should cover (with multi-master cluster)
- hashicorp/raft uses concrete types that cannot be easily mocked

* fix: address reviewer feedback on tests and leader routing

- Remove misleading tests that couldn't properly validate their
  documented behavior without a real Raft cluster:
  - TestRaftLeadershipTransfer_GoraftNotSupported
  - TestRaftLeadershipTransfer_ValidationTargetIdWithoutAddress

- Change WithClient(false) to WithClient(true) for RaftLeadershipTransfer
  RPC to ensure the request is routed to the current leader

* Improve cluster.raft.transferLeader command

- Rename command from cluster.raft.leader.transfer to cluster.raft.transferLeader
- Add symmetric validation: -id and -address must be specified together
- Handle case where same leader is re-elected after transfer
- Add test for -address without -id validation
- Add docker compose file for 5-master raft cluster testing

weed/pb/master.proto

@@ -51,6 +51,8 @@ service Seaweed {
   }
   rpc RaftRemoveServer (RaftRemoveServerRequest) returns (RaftRemoveServerResponse) {
   }
+  rpc RaftLeadershipTransfer (RaftLeadershipTransferRequest) returns (RaftLeadershipTransferResponse) {
+  }
   rpc VolumeGrow (VolumeGrowRequest) returns (VolumeGrowResponse) {
   }
 }
@@ -443,5 +445,14 @@ message RaftListClusterServersResponse {
   repeated ClusterServers cluster_servers = 1;
 }
 
+message RaftLeadershipTransferRequest {
+  string target_id = 1;       // Optional: target server ID. If empty, transfers to any eligible follower
+  string target_address = 2;  // Optional: target server address. Required if target_id is specified
+}
+message RaftLeadershipTransferResponse {
+  string previous_leader = 1;
+  string new_leader = 2;
+}
+
 message VolumeGrowResponse {
 }

weed/pb/master_pb/master.pb.go

@@ -3690,6 +3690,110 @@ func (x *RaftListClusterServersResponse) GetClusterServers() []*RaftListClusterS
 	return nil
 }
 
+type RaftLeadershipTransferRequest struct {
+	state         protoimpl.MessageState `protogen:"open.v1"`
+	TargetId      string                 `protobuf:"bytes,1,opt,name=target_id,json=targetId,proto3" json:"target_id,omitempty"`                // Optional: target server ID. If empty, transfers to any eligible follower
+	TargetAddress string                 `protobuf:"bytes,2,opt,name=target_address,json=targetAddress,proto3" json:"target_address,omitempty"` // Optional: target server address. Required if target_id is specified
+	unknownFields protoimpl.UnknownFields
+	sizeCache     protoimpl.SizeCache
+}
+
+func (x *RaftLeadershipTransferRequest) Reset() {
+	*x = RaftLeadershipTransferRequest{}
+	mi := &file_master_proto_msgTypes[58]
+	ms := protoimpl.X.MessageStateOf(protoimpl.Pointer(x))
+	ms.StoreMessageInfo(mi)
+}
+
+func (x *RaftLeadershipTransferRequest) String() string {
+	return protoimpl.X.MessageStringOf(x)
+}
+
+func (*RaftLeadershipTransferRequest) ProtoMessage() {}
+
+func (x *RaftLeadershipTransferRequest) ProtoReflect() protoreflect.Message {
+	mi := &file_master_proto_msgTypes[58]
+	if x != nil {
+		ms := protoimpl.X.MessageStateOf(protoimpl.Pointer(x))
+		if ms.LoadMessageInfo() == nil {
+			ms.StoreMessageInfo(mi)
+		}
+		return ms
+	}
+	return mi.MessageOf(x)
+}
+
+// Deprecated: Use RaftLeadershipTransferRequest.ProtoReflect.Descriptor instead.
+func (*RaftLeadershipTransferRequest) Descriptor() ([]byte, []int) {
+	return file_master_proto_rawDescGZIP(), []int{58}
+}
+
+func (x *RaftLeadershipTransferRequest) GetTargetId() string {
+	if x != nil {
+		return x.TargetId
+	}
+	return ""
+}
+
+func (x *RaftLeadershipTransferRequest) GetTargetAddress() string {
+	if x != nil {
+		return x.TargetAddress
+	}
+	return ""
+}
+
+type RaftLeadershipTransferResponse struct {
+	state          protoimpl.MessageState `protogen:"open.v1"`
+	PreviousLeader string                 `protobuf:"bytes,1,opt,name=previous_leader,json=previousLeader,proto3" json:"previous_leader,omitempty"`
+	NewLeader      string                 `protobuf:"bytes,2,opt,name=new_leader,json=newLeader,proto3" json:"new_leader,omitempty"`
+	unknownFields  protoimpl.UnknownFields
+	sizeCache      protoimpl.SizeCache
+}
+
+func (x *RaftLeadershipTransferResponse) Reset() {
+	*x = RaftLeadershipTransferResponse{}
+	mi := &file_master_proto_msgTypes[59]
+	ms := protoimpl.X.MessageStateOf(protoimpl.Pointer(x))
+	ms.StoreMessageInfo(mi)
+}
+
+func (x *RaftLeadershipTransferResponse) String() string {
+	return protoimpl.X.MessageStringOf(x)
+}
+
+func (*RaftLeadershipTransferResponse) ProtoMessage() {}
+
+func (x *RaftLeadershipTransferResponse) ProtoReflect() protoreflect.Message {
+	mi := &file_master_proto_msgTypes[59]
+	if x != nil {
+		ms := protoimpl.X.MessageStateOf(protoimpl.Pointer(x))
+		if ms.LoadMessageInfo() == nil {
+			ms.StoreMessageInfo(mi)
+		}
+		return ms
+	}
+	return mi.MessageOf(x)
+}
+
+// Deprecated: Use RaftLeadershipTransferResponse.ProtoReflect.Descriptor instead.
+func (*RaftLeadershipTransferResponse) Descriptor() ([]byte, []int) {
+	return file_master_proto_rawDescGZIP(), []int{59}
+}
+
+func (x *RaftLeadershipTransferResponse) GetPreviousLeader() string {
+	if x != nil {
+		return x.PreviousLeader
+	}
+	return ""
+}
+
+func (x *RaftLeadershipTransferResponse) GetNewLeader() string {
+	if x != nil {
+		return x.NewLeader
+	}
+	return ""
+}
+
 type VolumeGrowResponse struct {
 	state         protoimpl.MessageState `protogen:"open.v1"`
 	unknownFields protoimpl.UnknownFields
@@ -3698,7 +3802,7 @@ type VolumeGrowResponse struct {
 
 func (x *VolumeGrowResponse) Reset() {
 	*x = VolumeGrowResponse{}
-	mi := &file_master_proto_msgTypes[58]
+	mi := &file_master_proto_msgTypes[60]
 	ms := protoimpl.X.MessageStateOf(protoimpl.Pointer(x))
 	ms.StoreMessageInfo(mi)
 }
@@ -3710,7 +3814,7 @@ func (x *VolumeGrowResponse) String() string {
 func (*VolumeGrowResponse) ProtoMessage() {}
 
 func (x *VolumeGrowResponse) ProtoReflect() protoreflect.Message {
-	mi := &file_master_proto_msgTypes[58]
+	mi := &file_master_proto_msgTypes[60]
 	if x != nil {
 		ms := protoimpl.X.MessageStateOf(protoimpl.Pointer(x))
 		if ms.LoadMessageInfo() == nil {
@@ -3723,7 +3827,7 @@ func (x *VolumeGrowResponse) ProtoReflect() protoreflect.Message {
 
 // Deprecated: Use VolumeGrowResponse.ProtoReflect.Descriptor instead.
 func (*VolumeGrowResponse) Descriptor() ([]byte, []int) {
-	return file_master_proto_rawDescGZIP(), []int{58}
+	return file_master_proto_rawDescGZIP(), []int{60}
 }
 
 type SuperBlockExtra_ErasureCoding struct {
@@ -3737,7 +3841,7 @@ type SuperBlockExtra_ErasureCoding struct {
 
 func (x *SuperBlockExtra_ErasureCoding) Reset() {
 	*x = SuperBlockExtra_ErasureCoding{}
-	mi := &file_master_proto_msgTypes[61]
+	mi := &file_master_proto_msgTypes[63]
 	ms := protoimpl.X.MessageStateOf(protoimpl.Pointer(x))
 	ms.StoreMessageInfo(mi)
 }
@@ -3749,7 +3853,7 @@ func (x *SuperBlockExtra_ErasureCoding) String() string {
 func (*SuperBlockExtra_ErasureCoding) ProtoMessage() {}
 
 func (x *SuperBlockExtra_ErasureCoding) ProtoReflect() protoreflect.Message {
-	mi := &file_master_proto_msgTypes[61]
+	mi := &file_master_proto_msgTypes[63]
 	if x != nil {
 		ms := protoimpl.X.MessageStateOf(protoimpl.Pointer(x))
 		if ms.LoadMessageInfo() == nil {
@@ -3798,7 +3902,7 @@ type LookupVolumeResponse_VolumeIdLocation struct {
 
 func (x *LookupVolumeResponse_VolumeIdLocation) Reset() {
 	*x = LookupVolumeResponse_VolumeIdLocation{}
-	mi := &file_master_proto_msgTypes[62]
+	mi := &file_master_proto_msgTypes[64]
 	ms := protoimpl.X.MessageStateOf(protoimpl.Pointer(x))
 	ms.StoreMessageInfo(mi)
 }
@@ -3810,7 +3914,7 @@ func (x *LookupVolumeResponse_VolumeIdLocation) String() string {
 func (*LookupVolumeResponse_VolumeIdLocation) ProtoMessage() {}
 
 func (x *LookupVolumeResponse_VolumeIdLocation) ProtoReflect() protoreflect.Message {
-	mi := &file_master_proto_msgTypes[62]
+	mi := &file_master_proto_msgTypes[64]
 	if x != nil {
 		ms := protoimpl.X.MessageStateOf(protoimpl.Pointer(x))
 		if ms.LoadMessageInfo() == nil {
@@ -3864,7 +3968,7 @@ type LookupEcVolumeResponse_EcShardIdLocation struct {
 
 func (x *LookupEcVolumeResponse_EcShardIdLocation) Reset() {
 	*x = LookupEcVolumeResponse_EcShardIdLocation{}
-	mi := &file_master_proto_msgTypes[67]
+	mi := &file_master_proto_msgTypes[69]
 	ms := protoimpl.X.MessageStateOf(protoimpl.Pointer(x))
 	ms.StoreMessageInfo(mi)
 }
@@ -3876,7 +3980,7 @@ func (x *LookupEcVolumeResponse_EcShardIdLocation) String() string {
 func (*LookupEcVolumeResponse_EcShardIdLocation) ProtoMessage() {}
 
 func (x *LookupEcVolumeResponse_EcShardIdLocation) ProtoReflect() protoreflect.Message {
-	mi := &file_master_proto_msgTypes[67]
+	mi := &file_master_proto_msgTypes[69]
 	if x != nil {
 		ms := protoimpl.X.MessageStateOf(protoimpl.Pointer(x))
 		if ms.LoadMessageInfo() == nil {
@@ -3919,7 +4023,7 @@ type ListClusterNodesResponse_ClusterNode struct {
 
 func (x *ListClusterNodesResponse_ClusterNode) Reset() {
 	*x = ListClusterNodesResponse_ClusterNode{}
-	mi := &file_master_proto_msgTypes[68]
+	mi := &file_master_proto_msgTypes[70]
 	ms := protoimpl.X.MessageStateOf(protoimpl.Pointer(x))
 	ms.StoreMessageInfo(mi)
 }
@@ -3931,7 +4035,7 @@ func (x *ListClusterNodesResponse_ClusterNode) String() string {
 func (*ListClusterNodesResponse_ClusterNode) ProtoMessage() {}
 
 func (x *ListClusterNodesResponse_ClusterNode) ProtoReflect() protoreflect.Message {
-	mi := &file_master_proto_msgTypes[68]
+	mi := &file_master_proto_msgTypes[70]
 	if x != nil {
 		ms := protoimpl.X.MessageStateOf(protoimpl.Pointer(x))
 		if ms.LoadMessageInfo() == nil {
@@ -3994,7 +4098,7 @@ type RaftListClusterServersResponse_ClusterServers struct {
 
 func (x *RaftListClusterServersResponse_ClusterServers) Reset() {
 	*x = RaftListClusterServersResponse_ClusterServers{}
-	mi := &file_master_proto_msgTypes[69]
+	mi := &file_master_proto_msgTypes[71]
 	ms := protoimpl.X.MessageStateOf(protoimpl.Pointer(x))
 	ms.StoreMessageInfo(mi)
 }
@@ -4006,7 +4110,7 @@ func (x *RaftListClusterServersResponse_ClusterServers) String() string {
 func (*RaftListClusterServersResponse_ClusterServers) ProtoMessage() {}
 
 func (x *RaftListClusterServersResponse_ClusterServers) ProtoReflect() protoreflect.Message {
-	mi := &file_master_proto_msgTypes[69]
+	mi := &file_master_proto_msgTypes[71]
 	if x != nil {
 		ms := protoimpl.X.MessageStateOf(protoimpl.Pointer(x))
 		if ms.LoadMessageInfo() == nil {
@@ -4405,8 +4509,15 @@ const file_master_proto_rawDesc = "" +
 	"\x02id\x18\x01 \x01(\tR\x02id\x12\x18\n" +
 	"\aaddress\x18\x02 \x01(\tR\aaddress\x12\x1a\n" +
 	"\bsuffrage\x18\x03 \x01(\tR\bsuffrage\x12\x1a\n" +
-	"\bisLeader\x18\x04 \x01(\bR\bisLeader\"\x14\n" +
+	"\bisLeader\x18\x04 \x01(\bR\bisLeader\"c\n" +
-	"\x12VolumeGrowResponse2\xd5\x0f\n" +
+	"\x1dRaftLeadershipTransferRequest\x12\x1b\n" +
+	"\ttarget_id\x18\x01 \x01(\tR\btargetId\x12%\n" +
+	"\x0etarget_address\x18\x02 \x01(\tR\rtargetAddress\"h\n" +
+	"\x1eRaftLeadershipTransferResponse\x12'\n" +
+	"\x0fprevious_leader\x18\x01 \x01(\tR\x0epreviousLeader\x12\x1d\n" +
+	"\n" +
+	"new_leader\x18\x02 \x01(\tR\tnewLeader\"\x14\n" +
+	"\x12VolumeGrowResponse2\xc6\x10\n" +
 	"\aSeaweed\x12I\n" +
 	"\rSendHeartbeat\x12\x14.master_pb.Heartbeat\x1a\x1c.master_pb.HeartbeatResponse\"\x00(\x010\x01\x12X\n" +
 	"\rKeepConnected\x12\x1f.master_pb.KeepConnectedRequest\x1a .master_pb.KeepConnectedResponse\"\x00(\x010\x01\x12Q\n" +
@@ -4431,7 +4542,8 @@ const file_master_proto_rawDesc = "" +
 	"\x04Ping\x12\x16.master_pb.PingRequest\x1a\x17.master_pb.PingResponse\"\x00\x12o\n" +
 	"\x16RaftListClusterServers\x12(.master_pb.RaftListClusterServersRequest\x1a).master_pb.RaftListClusterServersResponse\"\x00\x12T\n" +
 	"\rRaftAddServer\x12\x1f.master_pb.RaftAddServerRequest\x1a .master_pb.RaftAddServerResponse\"\x00\x12]\n" +
-	"\x10RaftRemoveServer\x12\".master_pb.RaftRemoveServerRequest\x1a#.master_pb.RaftRemoveServerResponse\"\x00\x12K\n" +
+	"\x10RaftRemoveServer\x12\".master_pb.RaftRemoveServerRequest\x1a#.master_pb.RaftRemoveServerResponse\"\x00\x12o\n" +
+	"\x16RaftLeadershipTransfer\x12(.master_pb.RaftLeadershipTransferRequest\x1a).master_pb.RaftLeadershipTransferResponse\"\x00\x12K\n" +
 	"\n" +
 	"VolumeGrow\x12\x1c.master_pb.VolumeGrowRequest\x1a\x1d.master_pb.VolumeGrowResponse\"\x00B2Z0github.com/seaweedfs/seaweedfs/weed/pb/master_pbb\x06proto3"
 
@@ -4447,7 +4559,7 @@ func file_master_proto_rawDescGZIP() []byte {
 	return file_master_proto_rawDescData
 }
 
-var file_master_proto_msgTypes = make([]protoimpl.MessageInfo, 70)
+var file_master_proto_msgTypes = make([]protoimpl.MessageInfo, 72)
 var file_master_proto_goTypes = []any{
 	(*Heartbeat)(nil),                             // 0: master_pb.Heartbeat
 	(*HeartbeatResponse)(nil),                     // 1: master_pb.HeartbeatResponse
@@ -4507,18 +4619,20 @@ var file_master_proto_goTypes = []any{
 	(*RaftRemoveServerResponse)(nil),              // 55: master_pb.RaftRemoveServerResponse
 	(*RaftListClusterServersRequest)(nil),         // 56: master_pb.RaftListClusterServersRequest
 	(*RaftListClusterServersResponse)(nil),        // 57: master_pb.RaftListClusterServersResponse
-	(*VolumeGrowResponse)(nil),                    // 58: master_pb.VolumeGrowResponse
+	(*RaftLeadershipTransferRequest)(nil),         // 58: master_pb.RaftLeadershipTransferRequest
-	nil,                                           // 59: master_pb.Heartbeat.MaxVolumeCountsEntry
+	(*RaftLeadershipTransferResponse)(nil),        // 59: master_pb.RaftLeadershipTransferResponse
-	nil,                                           // 60: master_pb.StorageBackend.PropertiesEntry
+	(*VolumeGrowResponse)(nil),                    // 60: master_pb.VolumeGrowResponse
-	(*SuperBlockExtra_ErasureCoding)(nil),         // 61: master_pb.SuperBlockExtra.ErasureCoding
+	nil,                                           // 61: master_pb.Heartbeat.MaxVolumeCountsEntry
-	(*LookupVolumeResponse_VolumeIdLocation)(nil), // 62: master_pb.LookupVolumeResponse.VolumeIdLocation
+	nil,                                           // 62: master_pb.StorageBackend.PropertiesEntry
-	nil, // 63: master_pb.DataNodeInfo.DiskInfosEntry
+	(*SuperBlockExtra_ErasureCoding)(nil),         // 63: master_pb.SuperBlockExtra.ErasureCoding
-	nil, // 64: master_pb.RackInfo.DiskInfosEntry
+	(*LookupVolumeResponse_VolumeIdLocation)(nil), // 64: master_pb.LookupVolumeResponse.VolumeIdLocation
-	nil, // 65: master_pb.DataCenterInfo.DiskInfosEntry
+	nil, // 65: master_pb.DataNodeInfo.DiskInfosEntry
-	nil, // 66: master_pb.TopologyInfo.DiskInfosEntry
+	nil, // 66: master_pb.RackInfo.DiskInfosEntry
-	(*LookupEcVolumeResponse_EcShardIdLocation)(nil),      // 67: master_pb.LookupEcVolumeResponse.EcShardIdLocation
+	nil, // 67: master_pb.DataCenterInfo.DiskInfosEntry
-	(*ListClusterNodesResponse_ClusterNode)(nil),          // 68: master_pb.ListClusterNodesResponse.ClusterNode
+	nil, // 68: master_pb.TopologyInfo.DiskInfosEntry
-	(*RaftListClusterServersResponse_ClusterServers)(nil), // 69: master_pb.RaftListClusterServersResponse.ClusterServers
+	(*LookupEcVolumeResponse_EcShardIdLocation)(nil),      // 69: master_pb.LookupEcVolumeResponse.EcShardIdLocation
+	(*ListClusterNodesResponse_ClusterNode)(nil),          // 70: master_pb.ListClusterNodesResponse.ClusterNode
+	(*RaftListClusterServersResponse_ClusterServers)(nil), // 71: master_pb.RaftListClusterServersResponse.ClusterServers
 }
 var file_master_proto_depIdxs = []int32{
 	2,  // 0: master_pb.Heartbeat.volumes:type_name -> master_pb.VolumeInformationMessage
@@ -4527,30 +4641,30 @@ var file_master_proto_depIdxs = []int32{
 	4,  // 3: master_pb.Heartbeat.ec_shards:type_name -> master_pb.VolumeEcShardInformationMessage
 	4,  // 4: master_pb.Heartbeat.new_ec_shards:type_name -> master_pb.VolumeEcShardInformationMessage
 	4,  // 5: master_pb.Heartbeat.deleted_ec_shards:type_name -> master_pb.VolumeEcShardInformationMessage
-	59, // 6: master_pb.Heartbeat.max_volume_counts:type_name -> master_pb.Heartbeat.MaxVolumeCountsEntry
+	61, // 6: master_pb.Heartbeat.max_volume_counts:type_name -> master_pb.Heartbeat.MaxVolumeCountsEntry
 	5,  // 7: master_pb.HeartbeatResponse.storage_backends:type_name -> master_pb.StorageBackend
-	60, // 8: master_pb.StorageBackend.properties:type_name -> master_pb.StorageBackend.PropertiesEntry
+	62, // 8: master_pb.StorageBackend.properties:type_name -> master_pb.StorageBackend.PropertiesEntry
-	61, // 9: master_pb.SuperBlockExtra.erasure_coding:type_name -> master_pb.SuperBlockExtra.ErasureCoding
+	63, // 9: master_pb.SuperBlockExtra.erasure_coding:type_name -> master_pb.SuperBlockExtra.ErasureCoding
 	9,  // 10: master_pb.KeepConnectedResponse.volume_location:type_name -> master_pb.VolumeLocation
 	10, // 11: master_pb.KeepConnectedResponse.cluster_node_update:type_name -> master_pb.ClusterNodeUpdate
-	62, // 12: master_pb.LookupVolumeResponse.volume_id_locations:type_name -> master_pb.LookupVolumeResponse.VolumeIdLocation
+	64, // 12: master_pb.LookupVolumeResponse.volume_id_locations:type_name -> master_pb.LookupVolumeResponse.VolumeIdLocation
 	14, // 13: master_pb.AssignResponse.replicas:type_name -> master_pb.Location
 	14, // 14: master_pb.AssignResponse.location:type_name -> master_pb.Location
 	20, // 15: master_pb.CollectionListResponse.collections:type_name -> master_pb.Collection
 	2,  // 16: master_pb.DiskInfo.volume_infos:type_name -> master_pb.VolumeInformationMessage
 	4,  // 17: master_pb.DiskInfo.ec_shard_infos:type_name -> master_pb.VolumeEcShardInformationMessage
-	63, // 18: master_pb.DataNodeInfo.diskInfos:type_name -> master_pb.DataNodeInfo.DiskInfosEntry
+	65, // 18: master_pb.DataNodeInfo.diskInfos:type_name -> master_pb.DataNodeInfo.DiskInfosEntry
 	26, // 19: master_pb.RackInfo.data_node_infos:type_name -> master_pb.DataNodeInfo
-	64, // 20: master_pb.RackInfo.diskInfos:type_name -> master_pb.RackInfo.DiskInfosEntry
+	66, // 20: master_pb.RackInfo.diskInfos:type_name -> master_pb.RackInfo.DiskInfosEntry
 	27, // 21: master_pb.DataCenterInfo.rack_infos:type_name -> master_pb.RackInfo
-	65, // 22: master_pb.DataCenterInfo.diskInfos:type_name -> master_pb.DataCenterInfo.DiskInfosEntry
+	67, // 22: master_pb.DataCenterInfo.diskInfos:type_name -> master_pb.DataCenterInfo.DiskInfosEntry
 	28, // 23: master_pb.TopologyInfo.data_center_infos:type_name -> master_pb.DataCenterInfo
-	66, // 24: master_pb.TopologyInfo.diskInfos:type_name -> master_pb.TopologyInfo.DiskInfosEntry
+	68, // 24: master_pb.TopologyInfo.diskInfos:type_name -> master_pb.TopologyInfo.DiskInfosEntry
 	29, // 25: master_pb.VolumeListResponse.topology_info:type_name -> master_pb.TopologyInfo
-	67, // 26: master_pb.LookupEcVolumeResponse.shard_id_locations:type_name -> master_pb.LookupEcVolumeResponse.EcShardIdLocation
+	69, // 26: master_pb.LookupEcVolumeResponse.shard_id_locations:type_name -> master_pb.LookupEcVolumeResponse.EcShardIdLocation
 	5,  // 27: master_pb.GetMasterConfigurationResponse.storage_backends:type_name -> master_pb.StorageBackend
-	68, // 28: master_pb.ListClusterNodesResponse.cluster_nodes:type_name -> master_pb.ListClusterNodesResponse.ClusterNode
+	70, // 28: master_pb.ListClusterNodesResponse.cluster_nodes:type_name -> master_pb.ListClusterNodesResponse.ClusterNode
-	69, // 29: master_pb.RaftListClusterServersResponse.cluster_servers:type_name -> master_pb.RaftListClusterServersResponse.ClusterServers
+	71, // 29: master_pb.RaftListClusterServersResponse.cluster_servers:type_name -> master_pb.RaftListClusterServersResponse.ClusterServers
 	14, // 30: master_pb.LookupVolumeResponse.VolumeIdLocation.locations:type_name -> master_pb.Location
 	25, // 31: master_pb.DataNodeInfo.DiskInfosEntry.value:type_name -> master_pb.DiskInfo
 	25, // 32: master_pb.RackInfo.DiskInfosEntry.value:type_name -> master_pb.DiskInfo
@@ -4579,32 +4693,34 @@ var file_master_proto_depIdxs = []int32{
 	56, // 55: master_pb.Seaweed.RaftListClusterServers:input_type -> master_pb.RaftListClusterServersRequest
 	52, // 56: master_pb.Seaweed.RaftAddServer:input_type -> master_pb.RaftAddServerRequest
 	54, // 57: master_pb.Seaweed.RaftRemoveServer:input_type -> master_pb.RaftRemoveServerRequest
-	16, // 58: master_pb.Seaweed.VolumeGrow:input_type -> master_pb.VolumeGrowRequest
+	58, // 58: master_pb.Seaweed.RaftLeadershipTransfer:input_type -> master_pb.RaftLeadershipTransferRequest
-	1,  // 59: master_pb.Seaweed.SendHeartbeat:output_type -> master_pb.HeartbeatResponse
+	16, // 59: master_pb.Seaweed.VolumeGrow:input_type -> master_pb.VolumeGrowRequest
-	11, // 60: master_pb.Seaweed.KeepConnected:output_type -> master_pb.KeepConnectedResponse
+	1,  // 60: master_pb.Seaweed.SendHeartbeat:output_type -> master_pb.HeartbeatResponse
-	13, // 61: master_pb.Seaweed.LookupVolume:output_type -> master_pb.LookupVolumeResponse
+	11, // 61: master_pb.Seaweed.KeepConnected:output_type -> master_pb.KeepConnectedResponse
-	17, // 62: master_pb.Seaweed.Assign:output_type -> master_pb.AssignResponse
+	13, // 62: master_pb.Seaweed.LookupVolume:output_type -> master_pb.LookupVolumeResponse
-	17, // 63: master_pb.Seaweed.StreamAssign:output_type -> master_pb.AssignResponse
+	17, // 63: master_pb.Seaweed.Assign:output_type -> master_pb.AssignResponse
-	19, // 64: master_pb.Seaweed.Statistics:output_type -> master_pb.StatisticsResponse
+	17, // 64: master_pb.Seaweed.StreamAssign:output_type -> master_pb.AssignResponse
-	22, // 65: master_pb.Seaweed.CollectionList:output_type -> master_pb.CollectionListResponse
+	19, // 65: master_pb.Seaweed.Statistics:output_type -> master_pb.StatisticsResponse
-	24, // 66: master_pb.Seaweed.CollectionDelete:output_type -> master_pb.CollectionDeleteResponse
+	22, // 66: master_pb.Seaweed.CollectionList:output_type -> master_pb.CollectionListResponse
-	31, // 67: master_pb.Seaweed.VolumeList:output_type -> master_pb.VolumeListResponse
+	24, // 67: master_pb.Seaweed.CollectionDelete:output_type -> master_pb.CollectionDeleteResponse
-	33, // 68: master_pb.Seaweed.LookupEcVolume:output_type -> master_pb.LookupEcVolumeResponse
+	31, // 68: master_pb.Seaweed.VolumeList:output_type -> master_pb.VolumeListResponse
-	35, // 69: master_pb.Seaweed.VacuumVolume:output_type -> master_pb.VacuumVolumeResponse
+	33, // 69: master_pb.Seaweed.LookupEcVolume:output_type -> master_pb.LookupEcVolumeResponse
-	37, // 70: master_pb.Seaweed.DisableVacuum:output_type -> master_pb.DisableVacuumResponse
+	35, // 70: master_pb.Seaweed.VacuumVolume:output_type -> master_pb.VacuumVolumeResponse
-	39, // 71: master_pb.Seaweed.EnableVacuum:output_type -> master_pb.EnableVacuumResponse
+	37, // 71: master_pb.Seaweed.DisableVacuum:output_type -> master_pb.DisableVacuumResponse
-	41, // 72: master_pb.Seaweed.VolumeMarkReadonly:output_type -> master_pb.VolumeMarkReadonlyResponse
+	39, // 72: master_pb.Seaweed.EnableVacuum:output_type -> master_pb.EnableVacuumResponse
-	43, // 73: master_pb.Seaweed.GetMasterConfiguration:output_type -> master_pb.GetMasterConfigurationResponse
+	41, // 73: master_pb.Seaweed.VolumeMarkReadonly:output_type -> master_pb.VolumeMarkReadonlyResponse
-	45, // 74: master_pb.Seaweed.ListClusterNodes:output_type -> master_pb.ListClusterNodesResponse
+	43, // 74: master_pb.Seaweed.GetMasterConfiguration:output_type -> master_pb.GetMasterConfigurationResponse
-	47, // 75: master_pb.Seaweed.LeaseAdminToken:output_type -> master_pb.LeaseAdminTokenResponse
+	45, // 75: master_pb.Seaweed.ListClusterNodes:output_type -> master_pb.ListClusterNodesResponse
-	49, // 76: master_pb.Seaweed.ReleaseAdminToken:output_type -> master_pb.ReleaseAdminTokenResponse
+	47, // 76: master_pb.Seaweed.LeaseAdminToken:output_type -> master_pb.LeaseAdminTokenResponse
-	51, // 77: master_pb.Seaweed.Ping:output_type -> master_pb.PingResponse
+	49, // 77: master_pb.Seaweed.ReleaseAdminToken:output_type -> master_pb.ReleaseAdminTokenResponse
-	57, // 78: master_pb.Seaweed.RaftListClusterServers:output_type -> master_pb.RaftListClusterServersResponse
+	51, // 78: master_pb.Seaweed.Ping:output_type -> master_pb.PingResponse
-	53, // 79: master_pb.Seaweed.RaftAddServer:output_type -> master_pb.RaftAddServerResponse
+	57, // 79: master_pb.Seaweed.RaftListClusterServers:output_type -> master_pb.RaftListClusterServersResponse
-	55, // 80: master_pb.Seaweed.RaftRemoveServer:output_type -> master_pb.RaftRemoveServerResponse
+	53, // 80: master_pb.Seaweed.RaftAddServer:output_type -> master_pb.RaftAddServerResponse
-	58, // 81: master_pb.Seaweed.VolumeGrow:output_type -> master_pb.VolumeGrowResponse
+	55, // 81: master_pb.Seaweed.RaftRemoveServer:output_type -> master_pb.RaftRemoveServerResponse
-	59, // [59:82] is the sub-list for method output_type
+	59, // 82: master_pb.Seaweed.RaftLeadershipTransfer:output_type -> master_pb.RaftLeadershipTransferResponse
-	36, // [36:59] is the sub-list for method input_type
+	60, // 83: master_pb.Seaweed.VolumeGrow:output_type -> master_pb.VolumeGrowResponse
+	60, // [60:84] is the sub-list for method output_type
+	36, // [36:60] is the sub-list for method input_type
 	36, // [36:36] is the sub-list for extension type_name
 	36, // [36:36] is the sub-list for extension extendee
 	0,  // [0:36] is the sub-list for field type_name
@@ -4621,7 +4737,7 @@ func file_master_proto_init() {
 			GoPackagePath: reflect.TypeOf(x{}).PkgPath(),
 			RawDescriptor: unsafe.Slice(unsafe.StringData(file_master_proto_rawDesc), len(file_master_proto_rawDesc)),
 			NumEnums:      0,
-			NumMessages:   70,
+			NumMessages:   72,
 			NumExtensions: 0,
 			NumServices:   1,
 		},

weed/pb/master_pb/master_grpc.pb.go

@@ -41,6 +41,7 @@ const (
 	Seaweed_RaftListClusterServers_FullMethodName = "/master_pb.Seaweed/RaftListClusterServers"
 	Seaweed_RaftAddServer_FullMethodName          = "/master_pb.Seaweed/RaftAddServer"
 	Seaweed_RaftRemoveServer_FullMethodName       = "/master_pb.Seaweed/RaftRemoveServer"
+	Seaweed_RaftLeadershipTransfer_FullMethodName = "/master_pb.Seaweed/RaftLeadershipTransfer"
 	Seaweed_VolumeGrow_FullMethodName             = "/master_pb.Seaweed/VolumeGrow"
 )
 
@@ -70,6 +71,7 @@ type SeaweedClient interface {
 	RaftListClusterServers(ctx context.Context, in *RaftListClusterServersRequest, opts ...grpc.CallOption) (*RaftListClusterServersResponse, error)
 	RaftAddServer(ctx context.Context, in *RaftAddServerRequest, opts ...grpc.CallOption) (*RaftAddServerResponse, error)
 	RaftRemoveServer(ctx context.Context, in *RaftRemoveServerRequest, opts ...grpc.CallOption) (*RaftRemoveServerResponse, error)
+	RaftLeadershipTransfer(ctx context.Context, in *RaftLeadershipTransferRequest, opts ...grpc.CallOption) (*RaftLeadershipTransferResponse, error)
 	VolumeGrow(ctx context.Context, in *VolumeGrowRequest, opts ...grpc.CallOption) (*VolumeGrowResponse, error)
 }
 
@@ -310,6 +312,16 @@ func (c *seaweedClient) RaftRemoveServer(ctx context.Context, in *RaftRemoveServ
 	return out, nil
 }
 
+func (c *seaweedClient) RaftLeadershipTransfer(ctx context.Context, in *RaftLeadershipTransferRequest, opts ...grpc.CallOption) (*RaftLeadershipTransferResponse, error) {
+	cOpts := append([]grpc.CallOption{grpc.StaticMethod()}, opts...)
+	out := new(RaftLeadershipTransferResponse)
+	err := c.cc.Invoke(ctx, Seaweed_RaftLeadershipTransfer_FullMethodName, in, out, cOpts...)
+	if err != nil {
+		return nil, err
+	}
+	return out, nil
+}
+
 func (c *seaweedClient) VolumeGrow(ctx context.Context, in *VolumeGrowRequest, opts ...grpc.CallOption) (*VolumeGrowResponse, error) {
 	cOpts := append([]grpc.CallOption{grpc.StaticMethod()}, opts...)
 	out := new(VolumeGrowResponse)
@@ -346,6 +358,7 @@ type SeaweedServer interface {
 	RaftListClusterServers(context.Context, *RaftListClusterServersRequest) (*RaftListClusterServersResponse, error)
 	RaftAddServer(context.Context, *RaftAddServerRequest) (*RaftAddServerResponse, error)
 	RaftRemoveServer(context.Context, *RaftRemoveServerRequest) (*RaftRemoveServerResponse, error)
+	RaftLeadershipTransfer(context.Context, *RaftLeadershipTransferRequest) (*RaftLeadershipTransferResponse, error)
 	VolumeGrow(context.Context, *VolumeGrowRequest) (*VolumeGrowResponse, error)
 	mustEmbedUnimplementedSeaweedServer()
 }
@@ -423,6 +436,9 @@ func (UnimplementedSeaweedServer) RaftAddServer(context.Context, *RaftAddServerR
 func (UnimplementedSeaweedServer) RaftRemoveServer(context.Context, *RaftRemoveServerRequest) (*RaftRemoveServerResponse, error) {
 	return nil, status.Errorf(codes.Unimplemented, "method RaftRemoveServer not implemented")
 }
+func (UnimplementedSeaweedServer) RaftLeadershipTransfer(context.Context, *RaftLeadershipTransferRequest) (*RaftLeadershipTransferResponse, error) {
+	return nil, status.Errorf(codes.Unimplemented, "method RaftLeadershipTransfer not implemented")
+}
 func (UnimplementedSeaweedServer) VolumeGrow(context.Context, *VolumeGrowRequest) (*VolumeGrowResponse, error) {
 	return nil, status.Errorf(codes.Unimplemented, "method VolumeGrow not implemented")
 }
@@ -810,6 +826,24 @@ func _Seaweed_RaftRemoveServer_Handler(srv interface{}, ctx context.Context, dec
 	return interceptor(ctx, in, info, handler)
 }
 
+func _Seaweed_RaftLeadershipTransfer_Handler(srv interface{}, ctx context.Context, dec func(interface{}) error, interceptor grpc.UnaryServerInterceptor) (interface{}, error) {
+	in := new(RaftLeadershipTransferRequest)
+	if err := dec(in); err != nil {
+		return nil, err
+	}
+	if interceptor == nil {
+		return srv.(SeaweedServer).RaftLeadershipTransfer(ctx, in)
+	}
+	info := &grpc.UnaryServerInfo{
+		Server:     srv,
+		FullMethod: Seaweed_RaftLeadershipTransfer_FullMethodName,
+	}
+	handler := func(ctx context.Context, req interface{}) (interface{}, error) {
+		return srv.(SeaweedServer).RaftLeadershipTransfer(ctx, req.(*RaftLeadershipTransferRequest))
+	}
+	return interceptor(ctx, in, info, handler)
+}
+
 func _Seaweed_VolumeGrow_Handler(srv interface{}, ctx context.Context, dec func(interface{}) error, interceptor grpc.UnaryServerInterceptor) (interface{}, error) {
 	in := new(VolumeGrowRequest)
 	if err := dec(in); err != nil {
@@ -911,6 +945,10 @@ var Seaweed_ServiceDesc = grpc.ServiceDesc{
 			MethodName: "RaftRemoveServer",
 			Handler:    _Seaweed_RaftRemoveServer_Handler,
 		},
+		{
+			MethodName: "RaftLeadershipTransfer",
+			Handler:    _Seaweed_RaftLeadershipTransfer_Handler,
+		},
 		{
 			MethodName: "VolumeGrow",
 			Handler:    _Seaweed_VolumeGrow_Handler,

weed/server/master_grpc_server_raft.go

@@ -90,3 +90,50 @@ func (ms *MasterServer) RaftRemoveServer(ctx context.Context, req *master_pb.Raf
 	}
 	return resp, nil
 }
+
+func (ms *MasterServer) RaftLeadershipTransfer(ctx context.Context, req *master_pb.RaftLeadershipTransferRequest) (*master_pb.RaftLeadershipTransferResponse, error) {
+	resp := &master_pb.RaftLeadershipTransferResponse{}
+
+	ms.Topo.RaftServerAccessLock.RLock()
+	defer ms.Topo.RaftServerAccessLock.RUnlock()
+
+	// Leadership transfer is only supported with hashicorp raft (-raftHashicorp=true)
+	// The default seaweedfs/raft (goraft) implementation does not support this feature
+	if ms.Topo.HashicorpRaft == nil {
+		if ms.Topo.RaftServer != nil {
+			return nil, fmt.Errorf("leadership transfer requires -raftHashicorp=true; the default raft implementation does not support this feature")
+		}
+		return nil, fmt.Errorf("raft not initialized (single master mode)")
+	}
+
+	if ms.Topo.HashicorpRaft.State() != raft.Leader {
+		leaderAddr, _ := ms.Topo.HashicorpRaft.LeaderWithID()
+		return nil, fmt.Errorf("this server is not the leader; current leader is %s", leaderAddr)
+	}
+
+	// Record previous leader
+	_, previousLeaderId := ms.Topo.HashicorpRaft.LeaderWithID()
+	resp.PreviousLeader = string(previousLeaderId)
+
+	var future raft.Future
+	if req.TargetId != "" && req.TargetAddress != "" {
+		// Transfer to specific server
+		future = ms.Topo.HashicorpRaft.LeadershipTransferToServer(
+			raft.ServerID(req.TargetId),
+			raft.ServerAddress(req.TargetAddress),
+		)
+	} else {
+		// Transfer to any eligible follower
+		future = ms.Topo.HashicorpRaft.LeadershipTransfer()
+	}
+
+	if err := future.Error(); err != nil {
+		return nil, fmt.Errorf("leadership transfer failed: %v", err)
+	}
+
+	// Get new leader info
+	_, newLeaderId := ms.Topo.HashicorpRaft.LeaderWithID()
+	resp.NewLeader = string(newLeaderId)
+
+	return resp, nil
+}

weed/server/master_grpc_server_raft_test.go

@@ -0,0 +1,109 @@
+package weed_server
+
+// These tests cover the Raft gRPC handlers in scenarios where Raft is not initialized
+// (single master mode). Testing with an initialized Raft cluster requires integration
+// tests with a multi-master setup, as hashicorp/raft uses concrete types that cannot
+// be easily mocked.
+//
+// Integration tests for RaftLeadershipTransfer should cover:
+// - Successful leadership transfer to any follower (auto-selection)
+// - Successful leadership transfer to a specific target server
+// - Error when caller is not the current leader
+// - Error when target server is not a voting member
+// - Error when target server is unreachable
+//
+// These scenarios are best tested with test/multi_master/ integration tests
+// using a real 3-node master cluster with -raftHashicorp=true.
+
+import (
+	"context"
+	"strings"
+	"testing"
+
+	"github.com/seaweedfs/seaweedfs/weed/pb/master_pb"
+	"github.com/seaweedfs/seaweedfs/weed/topology"
+)
+
+func TestRaftLeadershipTransfer_NoRaft(t *testing.T) {
+	// Test case: raft not initialized (single master mode)
+	ms := &MasterServer{
+		Topo: topology.NewTopology("test", nil, 0, 0, false),
+	}
+
+	ctx := context.Background()
+	req := &master_pb.RaftLeadershipTransferRequest{}
+
+	_, err := ms.RaftLeadershipTransfer(ctx, req)
+	if err == nil {
+		t.Error("expected error when raft is not initialized")
+	}
+
+	expectedMsg := "single master mode"
+	if err != nil && !strings.Contains(err.Error(), expectedMsg) {
+		t.Errorf("expected error message to contain %q, got %q", expectedMsg, err.Error())
+	}
+}
+
+func TestRaftListClusterServers_NoRaft(t *testing.T) {
+	// Test case: raft not initialized returns empty response
+	ms := &MasterServer{
+		Topo: topology.NewTopology("test", nil, 0, 0, false),
+	}
+
+	ctx := context.Background()
+	req := &master_pb.RaftListClusterServersRequest{}
+
+	resp, err := ms.RaftListClusterServers(ctx, req)
+	if err != nil {
+		t.Errorf("unexpected error: %v", err)
+	}
+	if resp == nil {
+		t.Error("expected non-nil response")
+	}
+	if len(resp.ClusterServers) != 0 {
+		t.Errorf("expected empty cluster servers, got %d", len(resp.ClusterServers))
+	}
+}
+
+func TestRaftAddServer_NoRaft(t *testing.T) {
+	// Test case: raft not initialized returns empty response
+	ms := &MasterServer{
+		Topo: topology.NewTopology("test", nil, 0, 0, false),
+	}
+
+	ctx := context.Background()
+	req := &master_pb.RaftAddServerRequest{
+		Id:      "test-server",
+		Address: "localhost:19333",
+		Voter:   true,
+	}
+
+	resp, err := ms.RaftAddServer(ctx, req)
+	if err != nil {
+		t.Errorf("unexpected error: %v", err)
+	}
+	if resp == nil {
+		t.Error("expected non-nil response")
+	}
+}
+
+func TestRaftRemoveServer_NoRaft(t *testing.T) {
+	// Test case: raft not initialized returns empty response
+	ms := &MasterServer{
+		Topo: topology.NewTopology("test", nil, 0, 0, false),
+	}
+
+	ctx := context.Background()
+	req := &master_pb.RaftRemoveServerRequest{
+		Id:    "test-server",
+		Force: true,
+	}
+
+	resp, err := ms.RaftRemoveServer(ctx, req)
+	if err != nil {
+		t.Errorf("unexpected error: %v", err)
+	}
+	if resp == nil {
+		t.Error("expected non-nil response")
+	}
+}

weed/shell/command_cluster_raft_leader_transfer.go

@@ -0,0 +1,144 @@
+package shell
+
+import (
+	"context"
+	"flag"
+	"fmt"
+	"io"
+	"time"
+
+	"github.com/seaweedfs/seaweedfs/weed/pb/master_pb"
+)
+
+func init() {
+	Commands = append(Commands, &commandRaftLeaderTransfer{})
+}
+
+type commandRaftLeaderTransfer struct{}
+
+func (c *commandRaftLeaderTransfer) Name() string {
+	return "cluster.raft.transferLeader"
+}
+
+func (c *commandRaftLeaderTransfer) Help() string {
+	return `transfer raft leadership to another master server
+
+	This command initiates a graceful leadership transfer from the current
+	leader to another server. Use this before performing maintenance on
+	the current leader to reduce errors in filers and other components.
+
+	Examples:
+		# Transfer to any eligible follower (auto-selection)
+		cluster.raft.transferLeader
+
+		# Transfer to a specific server
+		cluster.raft.transferLeader -id <server_id> -address <server_grpc_address>
+
+	Notes:
+		- Requires hashicorp raft (-raftHashicorp=true on master)
+		- This command must be sent to the current leader
+		- The target server must be a voting member of the raft cluster
+		- Use 'cluster.raft.ps' to list available servers and identify the leader
+`
+}
+
+func (c *commandRaftLeaderTransfer) HasTag(CommandTag) bool {
+	return false
+}
+
+func (c *commandRaftLeaderTransfer) Do(args []string, commandEnv *CommandEnv, writer io.Writer) error {
+	leaderTransferCommand := flag.NewFlagSet(c.Name(), flag.ContinueOnError)
+	targetId := leaderTransferCommand.String("id", "", "target server id (must be used with -address)")
+	targetAddress := leaderTransferCommand.String("address", "", "target server grpc address (must be used with -id)")
+
+	if err := leaderTransferCommand.Parse(args); err != nil {
+		return err
+	}
+
+	// Validate: id and address must be specified together
+	if *targetId != "" && *targetAddress == "" {
+		return fmt.Errorf("-address is required when -id is specified")
+	}
+	if *targetAddress != "" && *targetId == "" {
+		return fmt.Errorf("-id is required when -address is specified")
+	}
+
+	// First, show current cluster status
+	fmt.Fprintf(writer, "Checking current raft cluster status...\n")
+
+	var currentLeader string
+	err := commandEnv.MasterClient.WithClient(false, func(client master_pb.SeaweedClient) error {
+		ctx, cancel := context.WithTimeout(context.Background(), 10*time.Second)
+		defer cancel()
+
+		resp, err := client.RaftListClusterServers(ctx, &master_pb.RaftListClusterServersRequest{})
+		if err != nil {
+			return fmt.Errorf("failed to list cluster servers: %v", err)
+		}
+
+		if len(resp.ClusterServers) == 0 {
+			fmt.Fprintf(writer, "No raft cluster configured (single master mode)\n")
+			return fmt.Errorf("leadership transfer not available in single master mode")
+		}
+
+		fmt.Fprintf(writer, "Raft cluster has %d servers:\n", len(resp.ClusterServers))
+		for _, server := range resp.ClusterServers {
+			suffix := ""
+			if server.IsLeader {
+				suffix = " <- current leader"
+				currentLeader = server.Id
+			}
+			fmt.Fprintf(writer, "  %s %s [%s]%s\n", server.Id, server.Address, server.Suffrage, suffix)
+		}
+		return nil
+	})
+	if err != nil {
+		return err
+	}
+
+	if currentLeader == "" {
+		return fmt.Errorf("no leader found in cluster")
+	}
+
+	// Perform the transfer
+	targetDesc := "any eligible follower"
+	if *targetId != "" {
+		targetDesc = fmt.Sprintf("server %s (%s)", *targetId, *targetAddress)
+	}
+	fmt.Fprintf(writer, "\nTransferring leadership from %s to %s...\n", currentLeader, targetDesc)
+
+	err = commandEnv.MasterClient.WithClient(true, func(client master_pb.SeaweedClient) error {
+		ctx, cancel := context.WithTimeout(context.Background(), 30*time.Second)
+		defer cancel()
+
+		resp, err := client.RaftLeadershipTransfer(ctx, &master_pb.RaftLeadershipTransferRequest{
+			TargetId:      *targetId,
+			TargetAddress: *targetAddress,
+		})
+		if err != nil {
+			return fmt.Errorf("leadership transfer failed: %v", err)
+		}
+
+		if resp.PreviousLeader != resp.NewLeader {
+			fmt.Fprintf(writer, "Leadership successfully transferred.\n")
+			fmt.Fprintf(writer, "  Previous leader: %s\n", resp.PreviousLeader)
+			fmt.Fprintf(writer, "  New leader: %s\n", resp.NewLeader)
+		} else {
+			fmt.Fprintf(writer, "Leadership transfer initiated, but the same leader was re-elected.\n")
+			fmt.Fprintf(writer, "  Current leader: %s\n", resp.NewLeader)
+		}
+		return nil
+	})
+
+	if err != nil {
+		fmt.Fprintf(writer, "\nLeadership transfer failed: %v\n", err)
+		fmt.Fprintf(writer, "\nTroubleshooting:\n")
+		fmt.Fprintf(writer, "  - Ensure you are connected to the current leader\n")
+		fmt.Fprintf(writer, "  - Ensure target server is a voting member (use 'cluster.raft.ps')\n")
+		fmt.Fprintf(writer, "  - Ensure target server is healthy and reachable\n")
+		return err
+	}
+
+	return nil
+}
+

weed/shell/command_cluster_raft_leader_transfer_test.go

@@ -0,0 +1,89 @@
+package shell
+
+import (
+	"bytes"
+	"strings"
+	"testing"
+)
+
+func TestRaftLeaderTransfer_Name(t *testing.T) {
+	cmd := &commandRaftLeaderTransfer{}
+	expected := "cluster.raft.transferLeader"
+	if cmd.Name() != expected {
+		t.Errorf("expected name %q, got %q", expected, cmd.Name())
+	}
+}
+
+func TestRaftLeaderTransfer_Help(t *testing.T) {
+	cmd := &commandRaftLeaderTransfer{}
+	help := cmd.Help()
+
+	// Verify help text contains key information
+	expectedPhrases := []string{
+		"transfer raft leadership",
+		"cluster.raft.transferLeader",
+		"-id",
+		"-address",
+		"cluster.raft.ps",
+		"-raftHashicorp",
+	}
+
+	for _, phrase := range expectedPhrases {
+		if !strings.Contains(help, phrase) {
+			t.Errorf("help text should contain %q", phrase)
+		}
+	}
+}
+
+func TestRaftLeaderTransfer_HasTag(t *testing.T) {
+	cmd := &commandRaftLeaderTransfer{}
+	// The command should not have any special tags
+	if cmd.HasTag(ResourceHeavy) {
+		t.Error("expected HasTag to return false for ResourceHeavy")
+	}
+}
+
+func TestRaftLeaderTransfer_ValidateTargetIdWithoutAddress(t *testing.T) {
+	cmd := &commandRaftLeaderTransfer{}
+	var buf bytes.Buffer
+
+	// Create a mock command environment - this will fail because no master client
+	// but we can verify argument parsing
+	err := cmd.Do([]string{"-id", "test-server"}, nil, &buf)
+
+	// Should fail because -address is required when -id is specified
+	if err == nil {
+		t.Error("expected error when -id is specified without -address")
+	}
+	if err != nil && !strings.Contains(err.Error(), "-address is required") {
+		t.Errorf("expected error about missing -address, got: %v", err)
+	}
+}
+
+func TestRaftLeaderTransfer_ValidateTargetAddressWithoutId(t *testing.T) {
+	cmd := &commandRaftLeaderTransfer{}
+	var buf bytes.Buffer
+
+	// Verify argument parsing - address without id should fail
+	err := cmd.Do([]string{"-address", "localhost:19333"}, nil, &buf)
+
+	// Should fail because -id is required when -address is specified
+	if err == nil {
+		t.Error("expected error when -address is specified without -id")
+	}
+	if err != nil && !strings.Contains(err.Error(), "-id is required") {
+		t.Errorf("expected error about missing -id, got: %v", err)
+	}
+}
+
+func TestRaftLeaderTransfer_UnknownFlag(t *testing.T) {
+	cmd := &commandRaftLeaderTransfer{}
+	var buf bytes.Buffer
+
+	// Unknown flag should return an error
+	err := cmd.Do([]string{"-unknown-flag"}, nil, &buf)
+	if err == nil {
+		t.Error("expected error for unknown flag")
+	}
+}
+