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serf_node.go
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serf_node.go
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package funk
import (
"errors"
"fmt"
"log"
"net"
"os"
"strconv"
"strings"
"sync"
"time"
"github.com/lab5e/clusterfunk/pkg/lg"
"github.com/lab5e/gotoolbox/netutils"
"github.com/hashicorp/serf/serf"
)
// SerfEventType is the type of events the SerfNode emits
type SerfEventType int
// Serf event types.
const (
SerfNodeJoined SerfEventType = iota // A node joins the cluster
SerfNodeLeft // A node has left the cluster
SerfNodeUpdated // A node's tags are updated
)
var (
// SerfLeft is the status of the serf node when it has left the cluster
SerfLeft = serf.StatusLeft.String()
// SerfAlive is the status of the serf node when it is alive and well
SerfAlive = serf.StatusAlive.String()
// SerfFailed is the status of the serf node when it has failed
SerfFailed = serf.StatusFailed.String()
)
func (s SerfEventType) String() string {
switch s {
case SerfNodeJoined:
return "SerfNodeJoined"
case SerfNodeLeft:
return "SerfNodeLeft"
case SerfNodeUpdated:
return "SerfNodeUpdated"
default:
panic(fmt.Sprintf("Unknown serf node type %d", s))
}
}
// NodeEvent is used for channel notifications
type NodeEvent struct {
Event SerfEventType
Node SerfMember
}
// SerfMember holds information on members in the Serf cluster.
type SerfMember struct {
NodeID string
State string
Tags map[string]string
}
// SerfNode is a wrapper around the Serf library
type SerfNode struct {
mutex *sync.RWMutex
se *serf.Serf
tags map[string]string // Local tags.
changedTags bool // Keeps track of changes in tags.
notifications []chan NodeEvent
members map[string]SerfMember
}
// NewSerfNode creates a new SerfNode instance
func NewSerfNode() *SerfNode {
ret := &SerfNode{
mutex: &sync.RWMutex{},
tags: make(map[string]string),
notifications: make([]chan NodeEvent, 0),
members: make(map[string]SerfMember),
}
return ret
}
// SerfParameters holds parameters for the Serf client
type SerfParameters struct {
Endpoint string `kong:"help='Endpoint for Serf',default=''"`
JoinAddress []string `kong:"help='Join address and port for Serf cluster'"`
Verbose bool `kong:"help='Verbose logging for Serf'"`
SnapshotPath string `kong:"help='Snapshot path (for persistence)'"`
}
// Final populates empty fields with default values
func (s *SerfParameters) Final() {
if s.Endpoint == "" {
s.Endpoint = netutils.RandomPublicEndpoint()
}
}
// Start launches the serf node. The service name can be left blank for clients.
func (s *SerfNode) Start(nodeID string, serviceName string, cfg SerfParameters) error {
s.mutex.Lock()
defer s.mutex.Unlock()
if s.se != nil {
return errors.New("serf node is already started")
}
config := serf.DefaultConfig()
config.NodeName = nodeID
host, portStr, err := net.SplitHostPort(cfg.Endpoint)
if err != nil {
return err
}
port, err := strconv.ParseInt(portStr, 10, 32)
if err != nil {
return err
}
// Lower the default reap and tombstone intervals
// The tombstone timeout is for nodes that leave
// gracefully.
config.ReapInterval = time.Minute * 5
config.TombstoneTimeout = time.Minute * 10
config.MemberlistConfig.BindAddr = host
config.MemberlistConfig.BindPort = int(port)
// The advertise address is the public-reachable address. Since we're running on
// a LAN (or a LAN-like) infrastructure this is the public IP address of the host.
config.MemberlistConfig.AdvertiseAddr = host
config.MemberlistConfig.AdvertisePort = int(port)
// Snapshot path is blank by default, ie nothing is stored on disk but
// for *some* nodes this is required, particularly if you are using seed
// nodes in non-zeroconf environments (like AWS et al). The seed nodes are
// more or less a permanent fixture and should survive restarts even when
// *everything* restarts at once.
config.SnapshotPath = cfg.SnapshotPath
if cfg.SnapshotPath != "" {
// Attempt rejoin based on snapshot since this is what we most likely want
// when the snapshot path is set.
config.RejoinAfterLeave = true
}
config.Init()
eventCh := make(chan serf.Event)
config.EventCh = eventCh
if cfg.Verbose {
config.Logger = log.New(os.Stderr, "serf", log.LstdFlags)
} else {
mutedLogger := newMutedLogger()
config.Logger = mutedLogger
config.MemberlistConfig.Logger = mutedLogger
}
if serviceName != "" {
s.tags[SerfServiceName] = serviceName
}
// Assign tags
config.Tags = s.tags
go s.serfEventHandler(eventCh)
if s.se, err = serf.Create(config); err != nil {
return err
}
if len(cfg.JoinAddress) > 0 {
_, err := s.se.Join(cfg.JoinAddress, true)
if err != nil {
return err
}
}
return nil
}
// Stop shuts down the node
func (s *SerfNode) Stop() error {
s.mutex.Lock()
defer s.mutex.Unlock()
if s.se == nil {
return errors.New("serf node is not started")
}
if err := s.se.Leave(); err != nil {
return err
}
s.se = nil
return nil
}
// SetTag sets a tag on the serf node. The tags are not updated until PublishTags
// are called by the client
func (s *SerfNode) SetTag(name, value string) {
s.mutex.Lock()
defer s.mutex.Unlock()
if value == "" {
delete(s.tags, name)
return
}
s.tags[name] = value
s.changedTags = true
}
// GetClusterTag returns the first tag in the cluster that matches the name.
// if no matching tag is found an empty string is returned.
func (s *SerfNode) GetClusterTag(name string) string {
for _, node := range s.Nodes() {
for k, v := range node.Tags {
if k == name {
return v
}
}
}
return ""
}
// PublishTags publishes the tags to the other members of the cluster
func (s *SerfNode) PublishTags() error {
s.mutex.RLock()
defer s.mutex.RUnlock()
if s.se == nil {
// *technically* this should be an error but the tags will be published
// once the node goes live.
return nil
}
if !s.changedTags {
return nil
}
s.changedTags = false
return s.se.SetTags(s.tags)
}
// Events returns a notification channel. If the client isn't reading the events
// will be dropped.
func (s *SerfNode) Events() <-chan NodeEvent {
s.mutex.Lock()
defer s.mutex.Unlock()
newChan := make(chan NodeEvent)
s.notifications = append(s.notifications, newChan)
return newChan
}
// Node returns information on a particular node. If the node isn't found the
// node returned will be empty
func (s *SerfNode) Node(nodeID string) SerfMember {
s.mutex.RLock()
defer s.mutex.RUnlock()
return s.members[nodeID]
}
// Nodes returns a list of known member nodes
func (s *SerfNode) Nodes() []SerfMember {
s.mutex.RLock()
defer s.mutex.RUnlock()
ret := make([]SerfMember, 0)
for k, v := range s.members {
n := SerfMember{}
n.NodeID = k
n.Tags = make(map[string]string)
for name, value := range v.Tags {
n.Tags[name] = value
}
ret = append(ret, n)
}
return ret
}
// Size returns the size of the member list
func (s *SerfNode) Size() int {
s.mutex.RLock()
defer s.mutex.RUnlock()
return len(s.members)
}
// addMember adds a new member. Returns true if the member does not exist
func (s *SerfNode) addMember(nodeID string, state string, tags map[string]string) {
s.mutex.Lock()
defer s.mutex.Unlock()
existing, ok := s.members[nodeID]
if !ok {
existing = SerfMember{NodeID: nodeID, Tags: tags, State: state}
s.members[nodeID] = existing
s.sendEvent(NodeEvent{
Event: SerfNodeJoined,
Node: existing,
})
return
}
s.sendEvent(NodeEvent{
Event: SerfNodeUpdated,
Node: existing,
})
existing.Tags = tags
s.members[nodeID] = existing
}
// removeMember removes a member from the collection. Returns true if the member doe snot e
func (s *SerfNode) removeMember(nodeID string) {
s.mutex.Lock()
defer s.mutex.Unlock()
existing, ok := s.members[nodeID]
if !ok {
return
}
s.sendEvent(NodeEvent{
Event: SerfNodeLeft,
Node: existing,
})
delete(s.members, nodeID)
}
func (s *SerfNode) updateMember(nodeID string, tags map[string]string) {
s.mutex.Lock()
defer s.mutex.Unlock()
existing, ok := s.members[nodeID]
if !ok {
existing.NodeID = nodeID
existing.Tags = tags
s.sendEvent(NodeEvent{
Event: SerfNodeJoined,
Node: existing,
})
return
}
existing.Tags = tags
s.members[nodeID] = existing
s.sendEvent(NodeEvent{
Event: SerfNodeUpdated,
Node: existing,
})
}
func (s *SerfNode) sendEvent(ev NodeEvent) {
for _, v := range s.notifications {
select {
case v <- ev:
default:
}
}
}
func (s *SerfNode) serfEventHandler(events chan serf.Event) {
for ev := range events {
switch ev.EventType() {
case serf.EventMemberJoin:
e, ok := ev.(serf.MemberEvent)
if !ok {
continue
}
for _, v := range e.Members {
s.addMember(v.Name, v.Status.String(), v.Tags)
}
case serf.EventMemberLeave:
e, ok := ev.(serf.MemberEvent)
if !ok {
continue
}
for _, v := range e.Members {
s.removeMember(v.Name)
}
case serf.EventMemberUpdate:
// No need to process member updates
e, ok := ev.(serf.MemberEvent)
if !ok {
continue
}
for _, v := range e.Members {
s.updateMember(v.Name, v.Tags)
}
case serf.EventMemberFailed:
e, ok := ev.(serf.MemberEvent)
if !ok {
continue
}
for _, v := range e.Members {
s.removeMember(v.Name)
}
case serf.EventMemberReap, serf.EventUser, serf.EventQuery:
// Do nothing
default:
lg.Warning("Unknown Serf event: %s", ev)
}
}
}
// LoadMembers reads the list of existing members in the Serf cluster
func (s *SerfNode) LoadMembers() []SerfMember {
var ret []SerfMember
for _, v := range s.se.Members() {
newNode := SerfMember{
NodeID: v.Name,
State: v.Status.String(),
Tags: make(map[string]string),
}
for k, v := range v.Tags {
newNode.Tags[k] = v
}
ret = append(ret, newNode)
}
return ret
}
func (s *SerfNode) memberList() []Node {
var ret []Node
for _, v := range s.se.Members() {
ret = append(ret, Node{
ID: v.Name,
State: v.Status.String(),
Leader: false,
})
}
return ret
}
// ID returns the
func (s *SerfNode) ID() string {
return s.se.LocalMember().Name
}
// Endpoints returns all the endpoints in the cluster
func (s *SerfNode) Endpoints() []Endpoint {
s.mutex.RLock()
defer s.mutex.RUnlock()
// Get a refreshed list of endpoints from the serf implementation
endpoints := make([]Endpoint, 0)
if s.se == nil {
// TODO(stalehd): Consider changing the startup to make this a non-issue
panic("Serf node is nil. Can't retrieve endpoints without a running node")
}
for _, m := range s.se.Members() {
for k, v := range m.Tags {
if strings.HasPrefix(k, EndpointPrefix) {
endpoints = append(endpoints, Endpoint{
NodeID: m.Name,
Name: k,
ListenAddress: v,
})
}
}
}
return endpoints
}
type muteWriter struct {
}
func (m *muteWriter) Write(buf []byte) (int, error) {
return len(buf), nil
}
// GetMutedLogger returns a pointer to a Logger instance that is logging
// to the Big Bit Bucket In The Sky...or Cloud
func newMutedLogger() *log.Logger {
return log.New(&muteWriter{}, "sssh", log.LstdFlags)
}