/
sentinel.go
228 lines (198 loc) · 5.4 KB
/
sentinel.go
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package redeoraft
import (
"net"
"strconv"
"strings"
"github.com/bsm/redeo"
"github.com/bsm/redeo/resp"
"github.com/hashicorp/raft"
)
// Sentinel handler respond to a subset of SENTINEL commands and
// makes your server behave like an instance of a sentinel cluster.
//
// Implemented sub-commands are:
//
// SENTINELS - returns (abbreviated) peer attributes
// MASTER - returns (abbreviated) master attributes
// SLAVES - returns (abbreviated) slave attributes
// GET-MASTER-ADDR-BY-NAME - returns a the master address
func Sentinel(name string, r *raft.Raft, b *redeo.PubSubBroker) redeo.Handler {
if name == "" {
name = "mymaster"
} else {
name = strings.ToLower(name)
}
go func() {
prevIP, prevPort, _ := net.SplitHostPort(string(r.Leader()))
for range r.LeaderCh() {
currIP, currPort, _ := net.SplitHostPort(string(r.Leader()))
b.PublishMessage("+switch-master", strings.Join([]string{name, prevIP, prevPort, currIP, currPort}, " "))
prevIP, prevPort = currIP, currPort
}
}()
h := &sentinelHandler{Raft: r, Name: name}
return redeo.SubCommands{
"get-master-addr-by-name": redeo.HandlerFunc(h.GetMasterAddrByName),
"sentinels": redeo.HandlerFunc(h.Sentinels),
"master": redeo.HandlerFunc(h.Master),
"slaves": redeo.HandlerFunc(h.Slaves),
}
}
type sentinelHandler struct {
*raft.Raft
Name string
}
// GetMasterAddrByName handles get-master-addr-by-name sub-command
func (h *sentinelHandler) GetMasterAddrByName(w resp.ResponseWriter, c *resp.Command) {
if c.ArgN() != 1 {
w.AppendError(redeo.WrongNumberOfArgs(c.Name))
return
}
if name := c.Arg(0).String(); strings.ToLower(name) != h.Name {
w.AppendNil()
return
}
ip, port, _ := net.SplitHostPort(string(h.Leader()))
if ip == "" || port == "" {
w.AppendNil()
return
}
w.AppendArrayLen(2)
w.AppendBulkString(ip)
w.AppendBulkString(port)
}
// Sentinels handles sentinels sub-command
func (h sentinelHandler) Sentinels(w resp.ResponseWriter, c *resp.Command) {
if ok := h.validateMasterName(w, c); !ok {
return
}
peers, ok := h.validatePeers(w)
if !ok {
return
}
w.AppendArrayLen(len(peers))
for _, peer := range peers {
ip, port, _ := net.SplitHostPort(string(peer.Address))
w.AppendArrayLen(8)
w.AppendBulkString("name")
w.AppendBulkString(string(peer.Address))
w.AppendBulkString("runid")
w.AppendBulkString(string(peer.ID))
w.AppendBulkString("ip")
w.AppendBulkString(ip)
w.AppendBulkString("port")
w.AppendBulkString(port)
}
}
// Master handles master sub-command
func (h sentinelHandler) Master(w resp.ResponseWriter, c *resp.Command) {
if ok := h.validateMasterName(w, c); !ok {
return
}
peers, ok := h.validatePeers(w)
if !ok {
return
}
leader := h.Leader()
var master *raft.Server
for _, peer := range peers {
if peer.Address == leader {
master = &peer
break
}
}
if master == nil {
w.AppendNil()
return
}
ip, port, err := net.SplitHostPort(string(master.Address))
if err != nil {
w.AppendError("ERR " + err.Error())
return
}
numSlaves := strconv.Itoa(len(peers) - 1)
w.AppendArrayLen(16)
w.AppendBulkString("name")
w.AppendBulkString(h.Name)
w.AppendBulkString("ip")
w.AppendBulkString(ip)
w.AppendBulkString("port")
w.AppendBulkString(port)
w.AppendBulkString("runid")
w.AppendBulkString(string(master.ID))
w.AppendBulkString("flags")
w.AppendBulkString("master")
w.AppendBulkString("role-reported")
w.AppendBulkString("master")
w.AppendBulkString("num-slaves")
w.AppendBulkString(numSlaves)
w.AppendBulkString("num-other-sentinels")
w.AppendBulkString(numSlaves)
}
// Slaves handles slaves sub-command
func (h sentinelHandler) Slaves(w resp.ResponseWriter, c *resp.Command) {
if ok := h.validateMasterName(w, c); !ok {
return
}
peers, ok := h.validatePeers(w)
if !ok {
return
}
leader := h.Leader()
masterIP, masterPort, err := net.SplitHostPort(string(leader))
if err != nil {
w.AppendError("ERR " + err.Error())
return
}
slaves := make([]raft.Server, 0, len(peers)-1)
for _, peer := range peers {
if peer.Address != leader {
slaves = append(slaves, peer)
}
}
w.AppendArrayLen(len(slaves))
for _, slave := range slaves {
ip, port, _ := net.SplitHostPort(string(slave.Address))
w.AppendArrayLen(16)
w.AppendBulkString("name")
w.AppendBulkString(h.Name)
w.AppendBulkString("ip")
w.AppendBulkString(ip)
w.AppendBulkString("port")
w.AppendBulkString(port)
w.AppendBulkString("runid")
w.AppendBulkString(string(slave.ID))
w.AppendBulkString("flags")
w.AppendBulkString("slave")
w.AppendBulkString("role-reported")
w.AppendBulkString("slave")
w.AppendBulkString("master-host")
w.AppendBulkString(masterIP)
w.AppendBulkString("master-port")
w.AppendBulkString(masterPort)
}
}
func (h sentinelHandler) validateMasterName(w resp.ResponseWriter, c *resp.Command) bool {
if c.ArgN() != 1 {
w.AppendError(redeo.WrongNumberOfArgs(c.Name))
return false
}
if name := c.Arg(0).String(); strings.ToLower(name) != h.Name {
w.AppendError("ERR No such master with that name")
return false
}
return true
}
func (h sentinelHandler) validatePeers(w resp.ResponseWriter) ([]raft.Server, bool) {
future := h.GetConfiguration()
if err := future.Error(); err != nil {
w.AppendError("ERR " + err.Error())
return nil, false
}
srv := future.Configuration().Servers
if srv == nil {
w.AppendError("ERR no sentinels found")
return nil, false
}
return srv, true
}