open-consul/consul/serf.go

279 lines
8.0 KiB
Go

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", &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()
}
}