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server_serf.go
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server_serf.go
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package consul
import (
"errors"
"fmt"
"net"
"path/filepath"
"strings"
"time"
"github.com/hashicorp/go-hclog"
"github.com/hashicorp/memberlist"
"github.com/hashicorp/raft"
"github.com/hashicorp/serf/serf"
"github.com/hashicorp/consul/agent/consul/wanfed"
"github.com/hashicorp/consul/agent/metadata"
"github.com/hashicorp/consul/agent/structs"
"github.com/hashicorp/consul/lib"
libserf "github.com/hashicorp/consul/lib/serf"
"github.com/hashicorp/consul/logging"
)
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
)
type setupSerfOptions struct {
Config *serf.Config
EventCh chan serf.Event
SnapshotPath string
Listener net.Listener
// WAN only
WAN bool
// LAN only
Segment string
Partition string
}
// setupSerf is used to setup and initialize a Serf
func (s *Server) setupSerf(opts setupSerfOptions) (*serf.Serf, *serf.Config, error) {
conf, err := s.setupSerfConfig(opts)
if err != nil {
return nil, nil, err
}
cluster, err := serf.Create(conf)
if err != nil {
return nil, nil, err
}
return cluster, conf, nil
}
func (s *Server) setupSerfConfig(opts setupSerfOptions) (*serf.Config, error) {
if opts.Config == nil {
return nil, errors.New("serf config is a required field")
}
if opts.Listener == nil {
return nil, errors.New("listener is a required field")
}
if opts.WAN {
if opts.Segment != "" {
return nil, errors.New("cannot configure segments on the WAN serf pool")
}
if opts.Partition != "" {
return nil, errors.New("cannot configure partitions on the WAN serf pool")
}
}
conf := opts.Config
conf.Init()
if opts.WAN {
conf.NodeName = fmt.Sprintf("%s.%s", s.config.NodeName, s.config.Datacenter)
} else {
conf.NodeName = s.config.NodeName
if s.config.SerfWANConfig != nil {
serfBindPortWAN := s.config.SerfWANConfig.MemberlistConfig.BindPort
if serfBindPortWAN > 0 {
conf.Tags["wan_join_port"] = fmt.Sprintf("%d", serfBindPortWAN)
}
}
}
conf.Tags["role"] = "consul"
conf.Tags["dc"] = s.config.Datacenter
conf.Tags["segment"] = opts.Segment
conf.Tags["id"] = string(s.config.NodeID)
conf.Tags["vsn"] = fmt.Sprintf("%d", s.config.ProtocolVersion)
conf.Tags["vsn_min"] = fmt.Sprintf("%d", ProtocolVersionMin)
conf.Tags["vsn_max"] = fmt.Sprintf("%d", ProtocolVersionMax)
conf.Tags["raft_vsn"] = fmt.Sprintf("%d", s.config.RaftConfig.ProtocolVersion)
conf.Tags["build"] = s.config.Build
addr := opts.Listener.Addr().(*net.TCPAddr)
conf.Tags["port"] = fmt.Sprintf("%d", addr.Port)
if s.config.Bootstrap {
conf.Tags["bootstrap"] = "1"
}
if s.config.BootstrapExpect != 0 {
conf.Tags["expect"] = fmt.Sprintf("%d", s.config.BootstrapExpect)
}
if s.config.ReadReplica {
// DEPRECATED - This tag should be removed when we no longer want to support
// upgrades from 1.8.x and below
conf.Tags["nonvoter"] = "1"
conf.Tags["read_replica"] = "1"
}
if s.config.TLSConfig.CAPath != "" || s.config.TLSConfig.CAFile != "" {
conf.Tags["use_tls"] = "1"
}
// TODO(ACL-Legacy-Compat): remove in phase 2. These are kept for now to
// allow for upgrades.
if s.ACLResolver.ACLsEnabled() {
conf.Tags[metadata.TagACLs] = string(structs.ACLModeEnabled)
} else {
conf.Tags[metadata.TagACLs] = string(structs.ACLModeDisabled)
}
// feature flag: advertise support for federation states
conf.Tags["ft_fs"] = "1"
// feature flag: advertise support for service-intentions
conf.Tags["ft_si"] = "1"
var subLoggerName string
if opts.WAN {
subLoggerName = logging.WAN
} else {
subLoggerName = logging.LAN
}
// Wrap hclog in a standard logger wrapper for serf and memberlist
// We use the Intercept variant here to ensure that serf and memberlist logs
// can be streamed via the monitor endpoint
serfLogger := s.logger.
NamedIntercept(logging.Serf).
NamedIntercept(subLoggerName).
StandardLoggerIntercept(&hclog.StandardLoggerOptions{InferLevels: true})
memberlistLogger := s.logger.
NamedIntercept(logging.Memberlist).
NamedIntercept(subLoggerName).
StandardLoggerIntercept(&hclog.StandardLoggerOptions{InferLevels: true})
conf.MemberlistConfig.Logger = memberlistLogger
conf.Logger = serfLogger
conf.EventCh = opts.EventCh
conf.ProtocolVersion = protocolVersionMap[s.config.ProtocolVersion]
conf.RejoinAfterLeave = s.config.RejoinAfterLeave
if opts.WAN {
conf.Merge = &wanMergeDelegate{
localDatacenter: s.config.Datacenter,
}
} else {
conf.Merge = &lanMergeDelegate{
dc: s.config.Datacenter,
nodeID: s.config.NodeID,
nodeName: s.config.NodeName,
segment: opts.Segment,
partition: opts.Partition,
server: true,
}
}
if opts.WAN {
nt, err := memberlist.NewNetTransport(&memberlist.NetTransportConfig{
BindAddrs: []string{conf.MemberlistConfig.BindAddr},
BindPort: conf.MemberlistConfig.BindPort,
Logger: conf.MemberlistConfig.Logger,
})
if err != nil {
return nil, err
}
if s.config.ConnectMeshGatewayWANFederationEnabled {
mgwTransport, err := wanfed.NewTransport(
s.tlsConfigurator,
nt,
s.config.Datacenter,
s.gatewayLocator.PickGateway,
)
if err != nil {
return nil, err
}
conf.MemberlistConfig.Transport = mgwTransport
} else {
conf.MemberlistConfig.Transport = nt
}
}
// Until Consul supports this fully, we disable automatic resolution.
// When enabled, the Serf gossip may just turn off if we are the minority
// node which is rather unexpected.
conf.EnableNameConflictResolution = false
if opts.WAN && s.config.ConnectMeshGatewayWANFederationEnabled {
conf.MemberlistConfig.RequireNodeNames = true
conf.MemberlistConfig.DisableTcpPingsForNode = func(nodeName string) bool {
_, dc, err := wanfed.SplitNodeName(nodeName)
if err != nil {
return false // don't disable anything if we don't understand the node name
}
// If doing cross-dc we will be using TCP via the gateways so
// there's no need for an extra TCP request.
return s.config.Datacenter != dc
}
}
if !s.config.DevMode {
conf.SnapshotPath = filepath.Join(s.config.DataDir, opts.SnapshotPath)
}
if err := lib.EnsurePath(conf.SnapshotPath, false); err != nil {
return nil, err
}
conf.ReconnectTimeoutOverride = libserf.NewReconnectOverride(s.logger)
addEnterpriseSerfTags(conf.Tags, s.config.AgentEnterpriseMeta())
if s.config.OverrideInitialSerfTags != nil {
s.config.OverrideInitialSerfTags(conf.Tags)
}
return conf, nil
}
// 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, serf.EventMemberReap:
s.lanNodeFailed(e.(serf.MemberEvent))
s.localMemberEvent(e.(serf.MemberEvent))
case serf.EventUser:
s.localEvent(e.(serf.UserEvent))
case serf.EventMemberUpdate:
s.lanNodeUpdate(e.(serf.MemberEvent))
s.localMemberEvent(e.(serf.MemberEvent))
case serf.EventQuery: // Ignore
default:
s.logger.Warn("Unhandled LAN Serf Event", "event", 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.Info("New leader elected", "payload", string(event.Payload))
// Trigger the callback
if s.config.ServerUp != nil {
s.config.ServerUp()
}
case isUserEvent(name):
event.Name = rawUserEventName(name)
s.logger.Debug("User event", "event", event.Name)
// Trigger the callback
if s.config.UserEventHandler != nil {
s.config.UserEventHandler(event)
}
default:
if !s.handleEnterpriseUserEvents(event) {
s.logger.Warn("Unhandled local event", "event", 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, serverMeta := metadata.IsConsulServer(m)
if !ok || serverMeta.Segment != "" {
continue
}
s.logger.Info("Adding LAN server", "server", serverMeta.String())
// Update server lookup
s.serverLookup.AddServer(serverMeta)
// 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()
}
}
func (s *Server) lanNodeUpdate(me serf.MemberEvent) {
for _, m := range me.Members {
ok, serverMeta := metadata.IsConsulServer(m)
if !ok || serverMeta.Segment != "" {
continue
}
s.logger.Info("Updating LAN server", "server", serverMeta.String())
// Update server lookup
s.serverLookup.AddServer(serverMeta)
}
}
// 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.Error("Failed to read last raft index", "error", err)
return
}
if index != 0 {
s.logger.Info("Raft data found, disabling bootstrap mode")
s.config.BootstrapExpect = 0
return
}
if s.config.ReadReplica {
s.logger.Info("Read replicas cannot bootstrap raft")
return
}
// Scan for all the known servers.
members := s.serfLAN.Members()
var servers []metadata.Server
voters := 0
for _, member := range members {
valid, p := metadata.IsConsulServer(member)
if !valid {
continue
}
if p.Datacenter != s.config.Datacenter {
s.logger.Warn("Member has a conflicting datacenter, ignoring", "member", member)
continue
}
if p.Expect != 0 && p.Expect != s.config.BootstrapExpect {
s.logger.Error("Member has a conflicting expect value. All nodes should expect the same number.", "member", member)
return
}
if p.Bootstrap {
s.logger.Error("Member has bootstrap mode. Expect disabled.", "member", member)
return
}
if !p.ReadReplica {
voters++
}
servers = append(servers, *p)
}
// Skip if we haven't met the minimum expect count.
if voters < 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.ShortName, server.Addr,
"Status.Peers", &structs.DCSpecificRequest{Datacenter: s.config.Datacenter}, &peers); err != nil {
nextRetry := (1 << attempt) * time.Second
s.logger.Error("Failed to confirm peer status for server (will retry).",
"server", server.Name,
"retry_interval", nextRetry.String(),
"error", err,
)
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.Info("Existing Raft peers reported by server, disabling bootstrap mode", "server", server.Name)
s.config.BootstrapExpect = 0
return
}
}
// Attempt a live bootstrap!
var configuration raft.Configuration
var addrs []string
for _, server := range servers {
addr := server.Addr.String()
addrs = append(addrs, addr)
id := raft.ServerID(server.ID)
suffrage := raft.Voter
if server.ReadReplica {
suffrage = raft.Nonvoter
}
peer := raft.Server{
ID: id,
Address: raft.ServerAddress(addr),
Suffrage: suffrage,
}
configuration.Servers = append(configuration.Servers, peer)
}
s.logger.Info("Found expected number of peers, attempting bootstrap",
"peers", strings.Join(addrs, ","),
)
future := s.raft.BootstrapCluster(configuration)
if err := future.Error(); err != nil {
s.logger.Error("Failed to bootstrap cluster", "error", 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, serverMeta := metadata.IsConsulServer(m)
if !ok || serverMeta.Segment != "" {
continue
}
s.logger.Info("Removing LAN server", "server", serverMeta.String())
// Update id to address map
s.serverLookup.RemoveServer(serverMeta)
}
}