// NewServer creates a new EtcdServer from the supplied configuration. The
// configuration is considered static for the lifetime of the EtcdServer.
func NewServer(cfg *ServerConfig) (srv *EtcdServer, err error) {
st := store.New(StoreClusterPrefix, StoreKeysPrefix)
var (
w *wal.WAL
n raft.Node
s *raft.MemoryStorage
id types.ID
cl *membership.RaftCluster
)
if terr := fileutil.TouchDirAll(cfg.DataDir); terr != nil {
return nil, fmt.Errorf("cannot access data directory: %v", terr)
}
haveWAL := wal.Exist(cfg.WALDir())
if err = fileutil.TouchDirAll(cfg.SnapDir()); err != nil {
plog.Fatalf("create snapshot directory error: %v", err)
}
ss := snap.New(cfg.SnapDir())
bepath := path.Join(cfg.SnapDir(), databaseFilename)
beExist := fileutil.Exist(bepath)
var be backend.Backend
beOpened := make(chan struct{})
go func() {
be = backend.NewDefaultBackend(bepath)
beOpened <- struct{}{}
}()
select {
case <-beOpened:
case <-time.After(time.Second):
plog.Warningf("another etcd process is running with the same data dir and holding the file lock.")
plog.Warningf("waiting for it to exit before starting...")
<-beOpened
}
defer func() {
if err != nil {
be.Close()
}
}()
prt, err := rafthttp.NewRoundTripper(cfg.PeerTLSInfo, cfg.peerDialTimeout())
if err != nil {
return nil, err
}
var (
remotes []*membership.Member
snapshot *raftpb.Snapshot
)
switch {
case !haveWAL && !cfg.NewCluster:
if err = cfg.VerifyJoinExisting(); err != nil {
return nil, err
}
cl, err = membership.NewClusterFromURLsMap(cfg.InitialClusterToken, cfg.InitialPeerURLsMap)
if err != nil {
return nil, err
}
existingCluster, gerr := GetClusterFromRemotePeers(getRemotePeerURLs(cl, cfg.Name), prt)
if gerr != nil {
return nil, fmt.Errorf("cannot fetch cluster info from peer urls: %v", gerr)
}
if err = membership.ValidateClusterAndAssignIDs(cl, existingCluster); err != nil {
return nil, fmt.Errorf("error validating peerURLs %s: %v", existingCluster, err)
}
if !isCompatibleWithCluster(cl, cl.MemberByName(cfg.Name).ID, prt) {
return nil, fmt.Errorf("incompatible with current running cluster")
}
remotes = existingCluster.Members()
cl.SetID(existingCluster.ID())
cl.SetStore(st)
cl.SetBackend(be)
cfg.Print()
id, n, s, w = startNode(cfg, cl, nil)
case !haveWAL && cfg.NewCluster:
if err = cfg.VerifyBootstrap(); err != nil {
return nil, err
}
cl, err = membership.NewClusterFromURLsMap(cfg.InitialClusterToken, cfg.InitialPeerURLsMap)
if err != nil {
return nil, err
}
m := cl.MemberByName(cfg.Name)
if isMemberBootstrapped(cl, cfg.Name, prt, cfg.bootstrapTimeout()) {
return nil, fmt.Errorf("member %s has already been bootstrapped", m.ID)
}
if cfg.ShouldDiscover() {
var str string
str, err = discovery.JoinCluster(cfg.DiscoveryURL, cfg.DiscoveryProxy, m.ID, cfg.InitialPeerURLsMap.String())
if err != nil {
return nil, &DiscoveryError{Op: "join", Err: err}
}
var urlsmap types.URLsMap
urlsmap, err = types.NewURLsMap(str)
if err != nil {
return nil, err
}
if checkDuplicateURL(urlsmap) {
return nil, fmt.Errorf("discovery cluster %s has duplicate url", urlsmap)
}
if cl, err = membership.NewClusterFromURLsMap(cfg.InitialClusterToken, urlsmap); err != nil {
return nil, err
}
}
cl.SetStore(st)
cl.SetBackend(be)
cfg.PrintWithInitial()
id, n, s, w = startNode(cfg, cl, cl.MemberIDs())
case haveWAL:
if err = fileutil.IsDirWriteable(cfg.MemberDir()); err != nil {
return nil, fmt.Errorf("cannot write to member directory: %v", err)
}
if err = fileutil.IsDirWriteable(cfg.WALDir()); err != nil {
return nil, fmt.Errorf("cannot write to WAL directory: %v", err)
}
if cfg.ShouldDiscover() {
plog.Warningf("discovery token ignored since a cluster has already been initialized. Valid log found at %q", cfg.WALDir())
}
snapshot, err = ss.Load()
if err != nil && err != snap.ErrNoSnapshot {
return nil, err
}
if snapshot != nil {
if err = st.Recovery(snapshot.Data); err != nil {
plog.Panicf("recovered store from snapshot error: %v", err)
}
plog.Infof("recovered store from snapshot at index %d", snapshot.Metadata.Index)
}
cfg.Print()
if !cfg.ForceNewCluster {
id, cl, n, s, w = restartNode(cfg, snapshot)
} else {
id, cl, n, s, w = restartAsStandaloneNode(cfg, snapshot)
}
cl.SetStore(st)
cl.SetBackend(be)
cl.Recover(api.UpdateCapability)
if cl.Version() != nil && !cl.Version().LessThan(semver.Version{Major: 3}) && !beExist {
os.RemoveAll(bepath)
return nil, fmt.Errorf("database file (%v) of the backend is missing", bepath)
}
default:
return nil, fmt.Errorf("unsupported bootstrap config")
}
if terr := fileutil.TouchDirAll(cfg.MemberDir()); terr != nil {
return nil, fmt.Errorf("cannot access member directory: %v", terr)
}
sstats := &stats.ServerStats{
Name: cfg.Name,
ID: id.String(),
}
sstats.Initialize()
lstats := stats.NewLeaderStats(id.String())
heartbeat := time.Duration(cfg.TickMs) * time.Millisecond
srv = &EtcdServer{
readych: make(chan struct{}),
Cfg: cfg,
snapCount: cfg.SnapCount,
errorc: make(chan error, 1),
store: st,
r: raftNode{
isIDRemoved: func(id uint64) bool { return cl.IsIDRemoved(types.ID(id)) },
Node: n,
ticker: time.Tick(heartbeat),
// set up contention detectors for raft heartbeat message.
// expect to send a heartbeat within 2 heartbeat intervals.
td: contention.NewTimeoutDetector(2 * heartbeat),
heartbeat: heartbeat,
raftStorage: s,
storage: NewStorage(w, ss),
msgSnapC: make(chan raftpb.Message, maxInFlightMsgSnap),
readStateC: make(chan raft.ReadState, 1),
},
id: id,
attributes: membership.Attributes{Name: cfg.Name, ClientURLs: cfg.ClientURLs.StringSlice()},
cluster: cl,
stats: sstats,
lstats: lstats,
SyncTicker: time.Tick(500 * time.Millisecond),
peerRt: prt,
reqIDGen: idutil.NewGenerator(uint16(id), time.Now()),
forceVersionC: make(chan struct{}),
}
srv.applyV2 = &applierV2store{store: srv.store, cluster: srv.cluster}
srv.be = be
minTTL := time.Duration((3*cfg.ElectionTicks)/2) * heartbeat
// always recover lessor before kv. When we recover the mvcc.KV it will reattach keys to its leases.
// If we recover mvcc.KV first, it will attach the keys to the wrong lessor before it recovers.
srv.lessor = lease.NewLessor(srv.be, int64(math.Ceil(minTTL.Seconds())))
srv.kv = mvcc.New(srv.be, srv.lessor, &srv.consistIndex)
if beExist {
kvindex := srv.kv.ConsistentIndex()
// TODO: remove kvindex != 0 checking when we do not expect users to upgrade
// etcd from pre-3.0 release.
if snapshot != nil && kvindex < snapshot.Metadata.Index {
if kvindex != 0 {
return nil, fmt.Errorf("database file (%v index %d) does not match with snapshot (index %d).", bepath, kvindex, snapshot.Metadata.Index)
}
plog.Warningf("consistent index never saved (snapshot index=%d)", snapshot.Metadata.Index)
}
}
srv.consistIndex.setConsistentIndex(srv.kv.ConsistentIndex())
srv.authStore = auth.NewAuthStore(srv.be)
if h := cfg.AutoCompactionRetention; h != 0 {
srv.compactor = compactor.NewPeriodic(h, srv.kv, srv)
srv.compactor.Run()
}
srv.applyV3Base = &applierV3backend{srv}
if err = srv.restoreAlarms(); err != nil {
return nil, err
}
// TODO: move transport initialization near the definition of remote
tr := &rafthttp.Transport{
TLSInfo: cfg.PeerTLSInfo,
DialTimeout: cfg.peerDialTimeout(),
ID: id,
URLs: cfg.PeerURLs,
ClusterID: cl.ID(),
Raft: srv,
Snapshotter: ss,
ServerStats: sstats,
LeaderStats: lstats,
ErrorC: srv.errorc,
}
if err = tr.Start(); err != nil {
return nil, err
}
// add all remotes into transport
for _, m := range remotes {
if m.ID != id {
tr.AddRemote(m.ID, m.PeerURLs)
}
}
for _, m := range cl.Members() {
if m.ID != id {
tr.AddPeer(m.ID, m.PeerURLs)
}
}
srv.r.transport = tr
return srv, nil
}
// start prepares and starts raftNode in a new goroutine. It is no longer safe
// to modify the fields after it has been started.
// TODO: Ideally raftNode should get rid of the passed in server structure.
func (r *raftNode) start(s *EtcdServer) {
r.s = s
r.applyc = make(chan apply)
r.stopped = make(chan struct{})
r.done = make(chan struct{})
heartbeat := 200 * time.Millisecond
if s.Cfg != nil {
heartbeat = time.Duration(s.Cfg.TickMs) * time.Millisecond
}
// set up contention detectors for raft heartbeat message.
// expect to send a heartbeat within 2 heartbeat intervals.
r.td = contention.NewTimeoutDetector(2 * heartbeat)
go func() {
var syncC <-chan time.Time
defer r.onStop()
islead := false
for {
select {
case <-r.ticker:
r.Tick()
case rd := <-r.Ready():
if rd.SoftState != nil {
if lead := atomic.LoadUint64(&r.lead); rd.SoftState.Lead != raft.None && lead != rd.SoftState.Lead {
r.mu.Lock()
r.lt = time.Now()
r.mu.Unlock()
leaderChanges.Inc()
}
if rd.SoftState.Lead == raft.None {
hasLeader.Set(0)
} else {
hasLeader.Set(1)
}
atomic.StoreUint64(&r.lead, rd.SoftState.Lead)
if rd.RaftState == raft.StateLeader {
islead = true
// TODO: raft should send server a notification through chan when
// it promotes or demotes instead of modifying server directly.
syncC = r.s.SyncTicker
if r.s.lessor != nil {
r.s.lessor.Promote(r.s.Cfg.electionTimeout())
}
// TODO: remove the nil checking
// current test utility does not provide the stats
if r.s.stats != nil {
r.s.stats.BecomeLeader()
}
if r.s.compactor != nil {
r.s.compactor.Resume()
}
r.td.Reset()
} else {
islead = false
if r.s.lessor != nil {
r.s.lessor.Demote()
}
if r.s.compactor != nil {
r.s.compactor.Pause()
}
syncC = nil
}
}
raftDone := make(chan struct{}, 1)
ap := apply{
entries: rd.CommittedEntries,
snapshot: rd.Snapshot,
raftDone: raftDone,
}
select {
case r.applyc <- ap:
case <-r.stopped:
return
}
// the leader can write to its disk in parallel with replicating to the followers and them
// writing to their disks.
// For more details, check raft thesis 10.2.1
if islead {
r.s.send(rd.Messages)
}
if !raft.IsEmptySnap(rd.Snapshot) {
if err := r.storage.SaveSnap(rd.Snapshot); err != nil {
plog.Fatalf("raft save snapshot error: %v", err)
}
r.raftStorage.ApplySnapshot(rd.Snapshot)
plog.Infof("raft applied incoming snapshot at index %d", rd.Snapshot.Metadata.Index)
}
if err := r.storage.Save(rd.HardState, rd.Entries); err != nil {
plog.Fatalf("raft save state and entries error: %v", err)
}
if !raft.IsEmptyHardState(rd.HardState) {
proposalsCommitted.Set(float64(rd.HardState.Commit))
}
r.raftStorage.Append(rd.Entries)
if !islead {
r.s.send(rd.Messages)
}
raftDone <- struct{}{}
r.Advance()
case <-syncC:
r.s.sync(r.s.Cfg.ReqTimeout())
case <-r.stopped:
return
}
}
}()
}