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