package consul import ( "strings" "time" "github.com/hashicorp/consul/consul/agent" "github.com/hashicorp/raft" "github.com/hashicorp/serf/serf" ) const ( // StatusReap is used to update the status of a node if we // are handling a EventMemberReap StatusReap = serf.MemberStatus(-1) // userEventPrefix is pre-pended to a user event to distinguish it userEventPrefix = "consul:event:" // maxPeerRetries limits how many invalidate attempts are made maxPeerRetries = 6 // peerRetryBase is a baseline retry time peerRetryBase = 1 * time.Second ) // userEventName computes the name of a user event func userEventName(name string) string { return userEventPrefix + name } // isUserEvent checks if a serf event is a user event func isUserEvent(name string) bool { return strings.HasPrefix(name, userEventPrefix) } // rawUserEventName is used to get the raw user event name func rawUserEventName(name string) string { return strings.TrimPrefix(name, userEventPrefix) } // lanEventHandler is used to handle events from the lan Serf cluster func (s *Server) lanEventHandler() { for { select { case e := <-s.eventChLAN: switch e.EventType() { case serf.EventMemberJoin: s.lanNodeJoin(e.(serf.MemberEvent)) s.localMemberEvent(e.(serf.MemberEvent)) case serf.EventMemberLeave, serf.EventMemberFailed: s.lanNodeFailed(e.(serf.MemberEvent)) s.localMemberEvent(e.(serf.MemberEvent)) case serf.EventMemberReap: s.localMemberEvent(e.(serf.MemberEvent)) case serf.EventUser: s.localEvent(e.(serf.UserEvent)) case serf.EventMemberUpdate: s.localMemberEvent(e.(serf.MemberEvent)) case serf.EventQuery: // Ignore default: s.logger.Printf("[WARN] consul: Unhandled LAN Serf Event: %#v", e) } case <-s.shutdownCh: return } } } // localMemberEvent is used to reconcile Serf events with the strongly // consistent store if we are the current leader func (s *Server) localMemberEvent(me serf.MemberEvent) { // Do nothing if we are not the leader if !s.IsLeader() { return } // Check if this is a reap event isReap := me.EventType() == serf.EventMemberReap // Queue the members for reconciliation for _, m := range me.Members { // Change the status if this is a reap event if isReap { m.Status = StatusReap } select { case s.reconcileCh <- m: default: } } } // localEvent is called when we receive an event on the local Serf func (s *Server) localEvent(event serf.UserEvent) { // Handle only consul events if !strings.HasPrefix(event.Name, "consul:") { return } switch name := event.Name; { case name == newLeaderEvent: s.logger.Printf("[INFO] consul: New leader elected: %s", event.Payload) // Trigger the callback if s.config.ServerUp != nil { s.config.ServerUp() } case isUserEvent(name): event.Name = rawUserEventName(name) s.logger.Printf("[DEBUG] consul: User event: %s", event.Name) // Trigger the callback if s.config.UserEventHandler != nil { s.config.UserEventHandler(event) } default: s.logger.Printf("[WARN] consul: Unhandled local event: %v", event) } } // lanNodeJoin is used to handle join events on the LAN pool. func (s *Server) lanNodeJoin(me serf.MemberEvent) { for _, m := range me.Members { ok, parts := agent.IsConsulServer(m) if !ok { continue } s.logger.Printf("[INFO] consul: Adding LAN server %s", parts) // See if it's configured as part of our DC. if parts.Datacenter == s.config.Datacenter { s.localLock.Lock() s.localConsuls[raft.ServerAddress(parts.Addr.String())] = parts s.localLock.Unlock() } // If we're still expecting to bootstrap, may need to handle this. if s.config.BootstrapExpect != 0 { s.maybeBootstrap() } // Kick the join flooders. s.FloodNotify() } } // maybeBootstrap is used to handle bootstrapping when a new consul server joins. func (s *Server) maybeBootstrap() { // Bootstrap can only be done if there are no committed logs, remove our // expectations of bootstrapping. This is slightly cheaper than the full // check that BootstrapCluster will do, so this is a good pre-filter. index, err := s.raftStore.LastIndex() if err != nil { s.logger.Printf("[ERR] consul: Failed to read last raft index: %v", err) return } if index != 0 { s.logger.Printf("[INFO] consul: Raft data found, disabling bootstrap mode") s.config.BootstrapExpect = 0 return } // Scan for all the known servers. members := s.serfLAN.Members() var servers []agent.Server for _, member := range members { valid, p := agent.IsConsulServer(member) if !valid { continue } if p.Datacenter != s.config.Datacenter { s.logger.Printf("[ERR] consul: Member %v has a conflicting datacenter, ignoring", member) continue } if p.Expect != 0 && p.Expect != s.config.BootstrapExpect { s.logger.Printf("[ERR] consul: Member %v has a conflicting expect value. All nodes should expect the same number.", member) return } if p.Bootstrap { s.logger.Printf("[ERR] consul: Member %v has bootstrap mode. Expect disabled.", member) return } servers = append(servers, *p) } // Skip if we haven't met the minimum expect count. if len(servers) < s.config.BootstrapExpect { return } // Query each of the servers and make sure they report no Raft peers. for _, server := range servers { var peers []string // Retry with exponential backoff to get peer status from this server for attempt := uint(0); attempt < maxPeerRetries; attempt++ { if err := s.connPool.RPC(s.config.Datacenter, server.Addr, server.Version, "Status.Peers", server.UseTLS, &struct{}{}, &peers); err != nil { nextRetry := time.Duration((1 << attempt) * peerRetryBase) s.logger.Printf("[ERR] consul: Failed to confirm peer status for %s: %v. Retrying in "+ "%v...", server.Name, err, nextRetry.String()) time.Sleep(nextRetry) } else { break } } // Found a node with some Raft peers, stop bootstrap since there's // evidence of an existing cluster. We should get folded in by the // existing servers if that's the case, so it's cleaner to sit as a // candidate with no peers so we don't cause spurious elections. // It's OK this is racy, because even with an initial bootstrap // as long as one peer runs bootstrap things will work, and if we // have multiple peers bootstrap in the same way, that's OK. We // just don't want a server added much later to do a live bootstrap // and interfere with the cluster. This isn't required for Raft's // correctness because no server in the existing cluster will vote // for this server, but it makes things much more stable. if len(peers) > 0 { s.logger.Printf("[INFO] consul: Existing Raft peers reported by %s, disabling bootstrap mode", server.Name) s.config.BootstrapExpect = 0 return } } // Attempt a live bootstrap! var configuration raft.Configuration var addrs []string minRaftVersion, err := ServerMinRaftProtocol(members) if err != nil { s.logger.Printf("[ERR] consul: Failed to read server raft versions: %v", err) } for _, server := range servers { addr := server.Addr.String() addrs = append(addrs, addr) var id raft.ServerID if minRaftVersion >= 3 { id = raft.ServerID(server.ID) } else { id = raft.ServerID(addr) } peer := raft.Server{ ID: id, Address: raft.ServerAddress(addr), } configuration.Servers = append(configuration.Servers, peer) } s.logger.Printf("[INFO] consul: Found expected number of peers, attempting bootstrap: %s", strings.Join(addrs, ",")) future := s.raft.BootstrapCluster(configuration) if err := future.Error(); err != nil { s.logger.Printf("[ERR] consul: Failed to bootstrap cluster: %v", err) } // Bootstrapping complete, or failed for some reason, don't enter this // again. s.config.BootstrapExpect = 0 } // lanNodeFailed is used to handle fail events on the LAN pool. func (s *Server) lanNodeFailed(me serf.MemberEvent) { for _, m := range me.Members { ok, parts := agent.IsConsulServer(m) if !ok { continue } s.logger.Printf("[INFO] consul: Removing LAN server %s", parts) s.localLock.Lock() delete(s.localConsuls, raft.ServerAddress(parts.Addr.String())) s.localLock.Unlock() } }