Simplify Raft peer adds using only reconciliation

consul/leader.go

@@ -2,7 +2,9 @@ package consul
 
 import (
 	"github.com/hashicorp/consul/consul/structs"
+	"github.com/hashicorp/raft"
 	"github.com/hashicorp/serf/serf"
+	"net"
 	"time"
 )
 
@@ -38,7 +40,15 @@ func (s *Server) monitorLeadership() {
 // leaderLoop runs as long as we are the leader to run various
 // maintence activities
 func (s *Server) leaderLoop(stopCh chan struct{}) {
+	// Reconcile channel is only used once initial reconcile
+	// has succeeded
+	var reconcileCh chan serf.Member
+
 RECONCILE:
+	// Setup a reconciliation timer
+	reconcileCh = nil
+	interval := time.After(s.config.ReconcileInterval)
+
 	// Apply a raft barrier to ensure our FSM is caught up
 	barrier := s.raft.Barrier(0)
 	if err := barrier.Error(); err != nil {
@@ -52,15 +62,24 @@ RECONCILE:
 		goto WAIT
 	}
 
+	// Initial reconcile worked, now we can process the channel
+	// updates
+	reconcileCh = s.reconcileCh
+
 WAIT:
-	// Periodically reconcile as long as we are the leader
+	// Periodically reconcile as long as we are the leader,
+	// or when Serf events arrive
+	for {
 		select {
-	case <-time.After(s.config.ReconcileInterval):
-		goto RECONCILE
 		case <-stopCh:
 			return
 		case <-s.shutdownCh:
 			return
+		case <-interval:
+			goto RECONCILE
+		case member := <-reconcileCh:
+			s.reconcileMember(member)
+		}
 	}
 }
 
@@ -127,6 +146,11 @@ func (s *Server) handleAliveMember(member serf.Member) error {
 			Service: "consul",
 			Port:    port,
 		}
+
+		// Attempt to join the consul server
+		if err := s.joinConsulServer(member, port); err != nil {
+			return err
+		}
 	}
 
 	// Check if the node exists
@@ -220,6 +244,17 @@ func (s *Server) handleLeftMember(member serf.Member) error {
 	}
 	s.logger.Printf("[INFO] consul: member '%s' left, deregistering", member.Name)
 
+	// Remove from Raft peers if this was a server
+	if valid, _, port := isConsulServer(member); valid {
+		peer := &net.TCPAddr{IP: member.Addr, Port: port}
+		future := s.raft.RemovePeer(peer)
+		if err := future.Error(); err != nil && err != raft.UnknownPeer {
+			s.logger.Printf("[ERR] consul: failed to remove raft peer '%v': %v",
+				peer, err)
+			return err
+		}
+	}
+
 	// Deregister the node
 	req := structs.DeregisterRequest{
 		Datacenter: s.config.Datacenter,
@@ -228,3 +263,20 @@ func (s *Server) handleLeftMember(member serf.Member) error {
 	var out struct{}
 	return s.endpoints.Catalog.Deregister(&req, &out)
 }
+
+// joinConsulServer is used to try to join another consul server
+func (s *Server) joinConsulServer(m serf.Member, port int) error {
+	// Do not join ourself
+	if m.Name == s.config.NodeName {
+		return nil
+	}
+
+	// Attempt to add as a peer
+	var addr net.Addr = &net.TCPAddr{IP: m.Addr, Port: port}
+	future := s.raft.AddPeer(addr)
+	if err := future.Error(); err != nil && err != raft.KnownPeer {
+		s.logger.Printf("[ERR] consul: failed to add raft peer: %v", err)
+		return err
+	}
+	return nil
+}

consul/leader_test.go

@@ -188,3 +188,72 @@ func TestLeader_Reconcile(t *testing.T) {
 		t.Fatalf("client not registered")
 	}
 }
+
+func TestLeader_LeftServer(t *testing.T) {
+	dir1, s1 := testServer(t)
+	defer os.RemoveAll(dir1)
+	defer s1.Shutdown()
+
+	dir2, s2 := testServerDCBootstrap(t, "dc1", false)
+	defer os.RemoveAll(dir2)
+	defer s2.Shutdown()
+
+	dir3, s3 := testServerDCBootstrap(t, "dc1", false)
+	defer os.RemoveAll(dir3)
+	defer s3.Shutdown()
+	servers := []*Server{s1, s2, s3}
+
+	// Try to join
+	addr := fmt.Sprintf("127.0.0.1:%d",
+		s1.config.SerfLANConfig.MemberlistConfig.BindPort)
+	if _, err := s2.JoinLAN([]string{addr}); err != nil {
+		t.Fatalf("err: %v", err)
+	}
+	if _, err := s3.JoinLAN([]string{addr}); err != nil {
+		t.Fatalf("err: %v", err)
+	}
+
+	// Wait until we have 3 peers
+	start := time.Now()
+CHECK1:
+	for _, s := range servers {
+		peers, _ := s.raftPeers.Peers()
+		if len(peers) != 3 {
+			if time.Now().Sub(start) >= 2*time.Second {
+				t.Fatalf("should have 3 peers")
+			} else {
+				time.Sleep(100 * time.Millisecond)
+				goto CHECK1
+			}
+		}
+	}
+
+	// Kill any server
+	servers[0].Shutdown()
+
+	// Wait for failure detection
+	time.Sleep(500 * time.Millisecond)
+
+	// Force remove the non-leader (transition to left state)
+	if err := servers[1].RemoveFailedNode(servers[0].config.NodeName); err != nil {
+		t.Fatalf("err: %v", err)
+	}
+
+	// Wait for intent propagation
+	time.Sleep(500 * time.Millisecond)
+
+	// Wait until we have 2 peers
+	start = time.Now()
+CHECK2:
+	for _, s := range servers[1:] {
+		peers, _ := s.raftPeers.Peers()
+		if len(peers) != 2 {
+			if time.Now().Sub(start) >= 2*time.Second {
+				t.Fatalf("should have 2 peers")
+			} else {
+				time.Sleep(100 * time.Millisecond)
+				goto CHECK2
+			}
+		}
+	}
+}

consul/serf.go

@@ -1,10 +1,8 @@
 package consul
 
 import (
-	"github.com/hashicorp/raft"
 	"github.com/hashicorp/serf/serf"
 	"net"
-	"time"
 )
 
 // lanEventHandler is used to handle events from the lan Serf cluster
@@ -14,7 +12,6 @@ func (s *Server) lanEventHandler() {
 		case e := <-s.eventChLAN:
 			switch e.EventType() {
 			case serf.EventMemberJoin:
-				s.localJoin(e.(serf.MemberEvent))
 				fallthrough
 			case serf.EventMemberLeave:
 				fallthrough
@@ -62,27 +59,13 @@ func (s *Server) localMemberEvent(me serf.MemberEvent) {
 		return
 	}
 
-	// Dispatch an async handler for each member
+	// Queue the members for reconciliation
 	for _, m := range me.Members {
-		go s.reconcileMember(m)
+		select {
+		case s.reconcileCh <- m:
+		default:
 		}
 	}
-
-// localJoin is used to handle join events on the lan serf cluster
-func (s *Server) localJoin(me serf.MemberEvent) {
-	// Check for consul members
-	for _, m := range me.Members {
-		ok, dc, port := isConsulServer(m)
-		if !ok {
-			continue
-		}
-		if dc != s.config.Datacenter {
-			s.logger.Printf("[WARN] consul: server %s for datacenter %s has joined wrong cluster",
-				m.Name, dc)
-			continue
-		}
-		go s.joinConsulServer(m, port)
-	}
 }
 
 // remoteJoin is used to handle join events on the wan serf cluster
@@ -147,60 +130,3 @@ func (s *Server) remoteFailed(me serf.MemberEvent) {
 		s.remoteLock.Unlock()
 	}
 }
-
-// joinConsulServer is used to try to join another consul server
-func (s *Server) joinConsulServer(m serf.Member, port int) {
-	if m.Name == s.config.NodeName {
-		return
-	}
-	var addr net.Addr = &net.TCPAddr{IP: m.Addr, Port: port}
-	var future raft.Future
-
-CHECK:
-	// Get the Raft peers
-	peers, err := s.raftPeers.Peers()
-	if err != nil {
-		s.logger.Printf("[ERR] consul: failed to get raft peers: %v", err)
-		goto WAIT
-	}
-
-	// Bail if this node is already a peer
-	for _, p := range peers {
-		if p.String() == addr.String() {
-			return
-		}
-	}
-
-	// Bail if the node is not alive
-	if memberStatus(s.serfLAN.Members(), m.Name) != serf.StatusAlive {
-		return
-	}
-
-	// Attempt to add as a peer
-	future = s.raft.AddPeer(addr)
-	if err := future.Error(); err != nil {
-		s.logger.Printf("[ERR] consul: failed to add raft peer: %v", err)
-	} else {
-		return
-	}
-
-WAIT:
-	time.Sleep(500 * time.Millisecond)
-	select {
-	case <-s.shutdownCh:
-		return
-	default:
-		goto CHECK
-	}
-}
-
-// memberStatus scans a list of members for a matching one,
-// returning the status or StatusNone
-func memberStatus(members []serf.Member, name string) serf.MemberStatus {
-	for _, m := range members {
-		if m.Name == name {
-			return m.Status
-		}
-	}
-	return serf.StatusNone
-}

consul/server.go

@@ -53,6 +53,11 @@ type Server struct {
 	raftStore     *raft.MDBStore
 	raftTransport *raft.NetworkTransport
 
+	// 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
+
 	// remoteConsuls is used to track the known consuls in
 	// remote data centers. Used to do DC forwarding.
 	remoteConsuls map[string][]net.Addr
@@ -110,6 +115,7 @@ func NewServer(config *Config) (*Server, error) {
 		eventChLAN:    make(chan serf.Event, 256),
 		eventChWAN:    make(chan serf.Event, 256),
 		logger:        logger,
+		reconcileCh:   make(chan serf.Member, 32),
 		remoteConsuls: make(map[string][]net.Addr),
 		rpcClients:    make(map[net.Conn]struct{}),
 		rpcServer:     rpc.NewServer(),
@@ -202,7 +208,7 @@ func (s *Server) setupRaft() error {
 	}
 
 	// Create a transport layer
-	trans := raft.NewNetworkTransport(s.raftLayer, 3, 10*time.Second, s.config.LogOutput)
+	trans := raft.NewNetworkTransport(s.raftLayer, 3, 500*time.Millisecond, s.config.LogOutput)
 	s.raftTransport = trans
 
 	// Setup the peer store

consul/server_test.go

@@ -64,7 +64,7 @@ func testServerDCBootstrap(t *testing.T, dc string, bootstrap bool) (string, *Se
 	config.RaftConfig.HeartbeatTimeout = 40 * time.Millisecond
 	config.RaftConfig.ElectionTimeout = 40 * time.Millisecond
 
-	config.ReconcileInterval = 50 * time.Millisecond
+	config.ReconcileInterval = 100 * time.Millisecond
 
 	server, err := NewServer(config)
 	if err != nil {