Merge pull request #3450 from hashicorp/raft_peers_fix

Change member join reconcile step to process joining itself, to handl…

agent/consul/leader.go

@@ -626,11 +626,6 @@ func (s *Server) handleDeregisterMember(reason string, member serf.Member) error
 
 // joinConsulServer is used to try to join another consul server
 func (s *Server) joinConsulServer(m serf.Member, parts *metadata.Server) error {
-	// Do not join ourself
-	if m.Name == s.config.NodeName {
-		return nil
-	}
-
 	// Check for possibility of multiple bootstrap nodes
 	if parts.Bootstrap {
 		members := s.serfLAN.Members()
@@ -643,20 +638,28 @@ func (s *Server) joinConsulServer(m serf.Member, parts *metadata.Server) error {
 		}
 	}
 
-	addr := (&net.TCPAddr{IP: m.Addr, Port: parts.Port}).String()
-
-	minRaftProtocol, err := ServerMinRaftProtocol(s.serfLAN.Members())
-	if err != nil {
+	// Processing ourselves could result in trying to remove ourselves to
+	// fix up our address, which would make us step down. This is only
+	// safe to attempt if there are multiple servers available.
+	configFuture := s.raft.GetConfiguration()
+	if err := configFuture.Error(); err != nil {
+		s.logger.Printf("[ERR] consul: failed to get raft configuration: %v", err)
 		return err
 	}
+	if m.Name == s.config.NodeName {
+		if l := len(configFuture.Configuration().Servers); l < 3 {
+			s.logger.Printf("[DEBUG] consul: Skipping self join check for %q since the cluster is too small", m.Name)
+			return nil
+		}
+	}
 
 	// See if it's already in the configuration. It's harmless to re-add it
 	// but we want to avoid doing that if possible to prevent useless Raft
 	// log entries. If the address is the same but the ID changed, remove the
 	// old server before adding the new one.
-	configFuture := s.raft.GetConfiguration()
-	if err := configFuture.Error(); err != nil {
-		s.logger.Printf("[ERR] consul: failed to get raft configuration: %v", err)
+	addr := (&net.TCPAddr{IP: m.Addr, Port: parts.Port}).String()
+	minRaftProtocol, err := ServerMinRaftProtocol(s.serfLAN.Members())
+	if err != nil {
 		return err
 	}
 	for _, server := range configFuture.Configuration().Servers {