open-consul/consul/server.go

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package consul
import (
"fmt"
"github.com/hashicorp/raft"
"github.com/hashicorp/serf/serf"
"log"
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"net"
"net/rpc"
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"os"
"path/filepath"
"strconv"
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"sync"
"time"
)
// These are the protocol versions that Consul can _understand_. These are
// Consul-level protocol versions, that are used to configure the Serf
// protocol versions.
const (
ProtocolVersionMin uint8 = 1
ProtocolVersionMax = 1
)
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const (
serfLANSnapshot = "serf/local.snapshot"
serfWANSnapshot = "serf/remote.snapshot"
raftState = "raft/"
snapshotsRetained = 2
raftDBSize = 128 * 1024 * 1024 // Limit Raft log to 128MB
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)
// Server is Consul server which manages the service discovery,
// health checking, DC forwarding, Raft, and multiple Serf pools.
type Server struct {
config *Config
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// Connection pool to other consul servers
connPool *ConnPool
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// Endpoints holds our RPC endpoints
endpoints endpoints
// eventChLAN is used to receive events from the
// serf cluster in the datacenter
eventChLAN chan serf.Event
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// eventChWAN is used to receive events from the
// serf cluster that spans datacenters
eventChWAN chan serf.Event
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// fsm is the state machine used with Raft to provide
// strong consistency.
fsm *consulFSM
// Logger uses the provided LogOutput
logger *log.Logger
// The raft instance is used among Consul nodes within the
// DC to protect operations that require strong consistency
raft *raft.Raft
raftLayer *RaftLayer
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raftPeers raft.PeerStore
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raftStore *raft.MDBStore
raftTransport *raft.NetworkTransport
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// reconcileCh is used to pass events from the serf handler
// into the leader manager, so that the strong state can be
// updated
reconcileCh chan serf.Member
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// remoteConsuls is used to track the known consuls in
// remote data centers. Used to do DC forwarding.
remoteConsuls map[string][]net.Addr
remoteLock sync.RWMutex
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// rpcClients is used to track active clients
rpcClients map[net.Conn]struct{}
rpcClientLock sync.Mutex
// rpcListener is used to listen for incoming connections
rpcListener net.Listener
rpcServer *rpc.Server
// serfLAN is the Serf cluster maintained inside the DC
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// which contains all the DC nodes
serfLAN *serf.Serf
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// serfWAN is the Serf cluster maintained between DC's
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// which SHOULD only consist of Consul servers
serfWAN *serf.Serf
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shutdown bool
shutdownCh chan struct{}
shutdownLock sync.Mutex
}
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// Holds the RPC endpoints
type endpoints struct {
Catalog *Catalog
Health *Health
Raft *Raft
Status *Status
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KVS *KVS
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}
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// NewServer is used to construct a new Consul server from the
// configuration, potentially returning an error
func NewServer(config *Config) (*Server, error) {
// Check the protocol version
if err := config.CheckVersion(); err != nil {
return nil, err
}
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// Check for a data directory!
if config.DataDir == "" {
return nil, fmt.Errorf("Config must provide a DataDir")
}
// Ensure we have a log output
if config.LogOutput == nil {
config.LogOutput = os.Stderr
}
// Create a logger
logger := log.New(config.LogOutput, "", log.LstdFlags)
// Create server
s := &Server{
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config: config,
connPool: NewPool(time.Minute),
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eventChLAN: make(chan serf.Event, 256),
eventChWAN: make(chan serf.Event, 256),
logger: logger,
reconcileCh: make(chan serf.Member, 32),
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remoteConsuls: make(map[string][]net.Addr),
rpcClients: make(map[net.Conn]struct{}),
rpcServer: rpc.NewServer(),
shutdownCh: make(chan struct{}),
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}
// Initialize the RPC layer
if err := s.setupRPC(); err != nil {
s.Shutdown()
return nil, fmt.Errorf("Failed to start RPC layer: %v", err)
}
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// Initialize the Raft server
if err := s.setupRaft(); err != nil {
s.Shutdown()
return nil, fmt.Errorf("Failed to start Raft: %v", err)
}
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// Start the Serf listeners to prevent a deadlock
go s.lanEventHandler()
go s.wanEventHandler()
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// Initialize the lan Serf
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var err error
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s.serfLAN, err = s.setupSerf(config.SerfLANConfig,
s.eventChLAN, serfLANSnapshot)
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if err != nil {
s.Shutdown()
return nil, fmt.Errorf("Failed to start lan serf: %v", err)
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}
// Initialize the wan Serf
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s.serfWAN, err = s.setupSerf(config.SerfWANConfig,
s.eventChWAN, serfWANSnapshot)
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if err != nil {
s.Shutdown()
return nil, fmt.Errorf("Failed to start wan serf: %v", err)
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}
return s, nil
}
// setupSerf is used to setup and initialize a Serf
func (s *Server) setupSerf(conf *serf.Config, ch chan serf.Event, path string) (*serf.Serf, error) {
addr := s.rpcListener.Addr().(*net.TCPAddr)
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conf.Init()
conf.NodeName = s.config.NodeName
conf.Tags["role"] = "consul"
conf.Tags["dc"] = s.config.Datacenter
conf.Tags["vsn"] = fmt.Sprintf("%d", s.config.ProtocolVersion)
conf.Tags["vsn_min"] = fmt.Sprintf("%d", ProtocolVersionMin)
conf.Tags["vsn_max"] = fmt.Sprintf("%d", ProtocolVersionMax)
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conf.Tags["port"] = fmt.Sprintf("%d", addr.Port)
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if s.config.Bootstrap {
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conf.Tags["bootstrap"] = "1"
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}
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conf.MemberlistConfig.LogOutput = s.config.LogOutput
conf.LogOutput = s.config.LogOutput
conf.EventCh = ch
conf.SnapshotPath = filepath.Join(s.config.DataDir, path)
conf.ProtocolVersion = protocolVersionMap[s.config.ProtocolVersion]
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if err := ensurePath(conf.SnapshotPath, false); err != nil {
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return nil, err
}
return serf.Create(conf)
}
// setupRaft is used to setup and initialize Raft
func (s *Server) setupRaft() error {
// If we are in bootstrap mode, enable a single node cluster
if s.config.Bootstrap {
s.config.RaftConfig.EnableSingleNode = true
}
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// Create the base path
path := filepath.Join(s.config.DataDir, raftState)
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if err := ensurePath(path, true); err != nil {
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return err
}
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// Create the FSM
var err error
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s.fsm, err = NewFSM(s.config.LogOutput)
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if err != nil {
return err
}
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// Create the MDB store for logs and stable storage
store, err := raft.NewMDBStoreWithSize(path, raftDBSize)
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if err != nil {
return err
}
s.raftStore = store
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// Create the snapshot store
snapshots, err := raft.NewFileSnapshotStore(path, snapshotsRetained, s.config.LogOutput)
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if err != nil {
store.Close()
return err
}
// Create a transport layer
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trans := raft.NewNetworkTransport(s.raftLayer, 3, 10*time.Second, s.config.LogOutput)
s.raftTransport = trans
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// Setup the peer store
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s.raftPeers = raft.NewJSONPeers(path, trans)
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// Ensure local host is always included if we are in bootstrap mode
if s.config.Bootstrap {
peers, err := s.raftPeers.Peers()
if err != nil {
store.Close()
return err
}
if !raft.PeerContained(peers, trans.LocalAddr()) {
s.raftPeers.SetPeers(raft.AddUniquePeer(peers, trans.LocalAddr()))
}
}
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// Make sure we set the LogOutput
s.config.RaftConfig.LogOutput = s.config.LogOutput
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// Setup the Raft store
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s.raft, err = raft.NewRaft(s.config.RaftConfig, s.fsm, store, store,
snapshots, s.raftPeers, trans)
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if err != nil {
store.Close()
trans.Close()
return err
}
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// Start monitoring leadership
go s.monitorLeadership()
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return nil
}
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// setupRPC is used to setup the RPC listener
func (s *Server) setupRPC() error {
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// Create endpoints
s.endpoints.Status = &Status{s}
s.endpoints.Raft = &Raft{s}
s.endpoints.Catalog = &Catalog{s}
s.endpoints.Health = &Health{s}
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s.endpoints.KVS = &KVS{s}
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// Register the handlers
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s.rpcServer.Register(s.endpoints.Status)
s.rpcServer.Register(s.endpoints.Raft)
s.rpcServer.Register(s.endpoints.Catalog)
s.rpcServer.Register(s.endpoints.Health)
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s.rpcServer.Register(s.endpoints.KVS)
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list, err := net.ListenTCP("tcp", s.config.RPCAddr)
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if err != nil {
return err
}
s.rpcListener = list
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var advertise net.Addr
if s.config.RPCAdvertise != nil {
advertise = s.config.RPCAdvertise
} else {
advertise = s.rpcListener.Addr()
}
// Verify that we have a usable advertise address
addr, ok := advertise.(*net.TCPAddr)
if !ok {
list.Close()
return fmt.Errorf("RPC advertise address is not a TCP Address: %v", addr)
}
if addr.IP.IsUnspecified() {
list.Close()
return fmt.Errorf("RPC advertise address is not advertisable: %v", addr)
}
s.raftLayer = NewRaftLayer(advertise)
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go s.listen()
return nil
}
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// Shutdown is used to shutdown the server
func (s *Server) Shutdown() error {
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s.logger.Printf("[INFO] consul: shutting down server")
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s.shutdownLock.Lock()
defer s.shutdownLock.Unlock()
if s.shutdown {
return nil
}
s.shutdown = true
close(s.shutdownCh)
if s.serfLAN != nil {
s.serfLAN.Shutdown()
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}
if s.serfWAN != nil {
s.serfWAN.Shutdown()
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}
if s.raft != nil {
s.raftTransport.Close()
s.raftLayer.Close()
future := s.raft.Shutdown()
if err := future.Error(); err != nil {
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s.logger.Printf("[WARN] consul: Error shutting down raft: %s", err)
}
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s.raftStore.Close()
}
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if s.rpcListener != nil {
s.rpcListener.Close()
}
// Close all the RPC connections
s.rpcClientLock.Lock()
for conn := range s.rpcClients {
conn.Close()
}
s.rpcClientLock.Unlock()
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// Close the connection pool
s.connPool.Shutdown()
// Close the fsm
if s.fsm != nil {
s.fsm.Close()
}
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return nil
}
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// Leave is used to prepare for a graceful shutdown of the server
func (s *Server) Leave() error {
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s.logger.Printf("[INFO] consul: server starting leave")
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// Leave the WAN pool
if s.serfWAN != nil {
if err := s.serfWAN.Leave(); err != nil {
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s.logger.Printf("[ERR] consul: failed to leave WAN Serf cluster: %v", err)
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}
}
// Leave the LAN pool
if s.serfLAN != nil {
if err := s.serfLAN.Leave(); err != nil {
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s.logger.Printf("[ERR] consul: failed to leave LAN Serf cluster: %v", err)
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}
}
// Leave the Raft cluster
if s.raft != nil {
// Check if we have other raft nodes
peers, _ := s.raftPeers.Peers()
if len(peers) <= 1 {
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s.logger.Printf("[WARN] consul: not leaving Raft cluster, no peers")
goto AFTER_LEAVE
}
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// Get the leader
leader := s.raft.Leader()
if leader == nil {
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s.logger.Printf("[ERR] consul: failed to leave Raft cluster: no leader")
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goto AFTER_LEAVE
}
// Request that we are removed
ch := make(chan error, 1)
go func() {
var out struct{}
peer := s.raftTransport.LocalAddr().String()
err := s.connPool.RPC(leader, "Raft.RemovePeer", peer, &out)
ch <- err
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}()
// Wait for the commit
select {
case err := <-ch:
if err != nil {
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s.logger.Printf("[ERR] consul: failed to leave Raft cluster: %v", err)
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}
case <-time.After(3 * time.Second):
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s.logger.Printf("[ERR] consul: timed out leaving Raft cluster")
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}
}
AFTER_LEAVE:
return nil
}
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// JoinLAN is used to have Consul join the inner-DC pool
// The target address should be another node inside the DC
// listening on the Serf LAN address
func (s *Server) JoinLAN(addrs []string) (int, error) {
return s.serfLAN.Join(addrs, true)
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}
// JoinWAN is used to have Consul join the cross-WAN Consul ring
// The target address should be another node listening on the
// Serf WAN address
func (s *Server) JoinWAN(addrs []string) (int, error) {
return s.serfWAN.Join(addrs, true)
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}
// LANMembers is used to return the members of the LAN cluster
func (s *Server) LANMembers() []serf.Member {
return s.serfLAN.Members()
}
// WANMembers is used to return the members of the LAN cluster
func (s *Server) WANMembers() []serf.Member {
return s.serfWAN.Members()
}
// RemoveFailedNode is used to remove a failed node from the cluster
func (s *Server) RemoveFailedNode(node string) error {
if err := s.serfLAN.RemoveFailedNode(node); err != nil {
return err
}
if err := s.serfWAN.RemoveFailedNode(node); err != nil {
return err
}
return nil
}
// IsLeader checks if this server is the cluster leader
func (s *Server) IsLeader() bool {
return s.raft.State() == raft.Leader
}
// RPC is used to make a local RPC call
func (s *Server) RPC(method string, args interface{}, reply interface{}) error {
addr := s.rpcListener.Addr()
return s.connPool.RPC(addr, method, args, reply)
}
// Stats is used to return statistics for debugging and insight
// for various sub-systems
func (s *Server) Stats() map[string]map[string]string {
toString := func(v uint64) string {
return strconv.FormatUint(v, 10)
}
stats := map[string]map[string]string{
"consul": map[string]string{
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"server": "true",
"leader": fmt.Sprintf("%v", s.IsLeader()),
"bootstrap": fmt.Sprintf("%v", s.config.Bootstrap),
"known_datacenters": toString(uint64(len(s.remoteConsuls))),
},
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"raft": s.raft.Stats(),
"serf_lan": s.serfLAN.Stats(),
"serf_wan": s.serfWAN.Stats(),
}
return stats
}