func (server *ServerMonitor) rejoin() error {
	if readonly {
		dbhelper.SetReadOnly(server.Conn, true)
	}
	cm := "CHANGE MASTER TO master_host='" + master.IP + "', master_port=" + master.Port + ", master_user='******', master_password='******', MASTER_USE_GTID=CURRENT_POS"
	_, err := server.Conn.Exec(cm)
	dbhelper.StartSlave(server.Conn)
	return err
}
Exemplo n.º 2
0
/* Handles write freeze and existing transactions on a server */
func (server *ServerMonitor) freeze() bool {
	err := dbhelper.SetReadOnly(server.Conn, true)
	if err != nil {
		logprintf("WARN : Could not set %s as read-only: %s", server.URL, err)
		return false
	}
	for i := *waitKill; i > 0; i -= 500 {
		threads := dbhelper.CheckLongRunningWrites(server.Conn, 0)
		if threads == 0 {
			break
		}
		logprintf("INFO : Waiting for %d write threads to complete on %s", threads, server.URL)
		time.Sleep(500 * time.Millisecond)
	}
	logprintf("INFO : Terminating all threads on %s", server.URL)
	dbhelper.KillThreads(server.Conn)
	return true
}
Exemplo n.º 3
0
/* Triggers a master failover. Returns the new master's URL and key */
func (master *ServerMonitor) failover() (string, int) {
	log.Println("INFO : Starting failover and electing a new master")
	var nmUrl string
	key := master.electCandidate(slaves)
	if key == -1 {
		return "", -1
	}
	nmUrl = slaves[key].URL
	log.Printf("INFO : Slave %s has been elected as a new master", nmUrl)
	newMaster, err := newServerMonitor(nmUrl)
	if *preScript != "" {
		log.Printf("INFO : Calling pre-failover script")
		out, err := exec.Command(*preScript, master.Host, newMaster.Host).CombinedOutput()
		if err != nil {
			log.Println("ERROR:", err)
		}
		log.Println("INFO : Post-failover script complete:", string(out))
	}
	log.Println("INFO : Switching master")
	log.Println("INFO : Stopping slave thread on new master")
	err = dbhelper.StopSlave(newMaster.Conn)
	if err != nil {
		log.Println("WARN : Stopping slave failed on new master")
	}
	cm := "CHANGE MASTER TO master_host='" + newMaster.IP + "', master_port=" + newMaster.Port + ", master_user='******', master_password='******'"
	log.Println("INFO : Resetting slave on new master and set read/write mode on")
	err = dbhelper.ResetSlave(newMaster.Conn, true)
	if err != nil {
		log.Println("WARN : Reset slave failed on new master")
	}
	err = dbhelper.SetReadOnly(newMaster.Conn, false)
	if err != nil {
		log.Println("ERROR: Could not set new master as read-write")
	}
	log.Println("INFO : Switching other slaves to the new master")
	for _, sl := range slaves {
		log.Printf("INFO : Change master on slave %s", sl.URL)
		err := dbhelper.StopSlave(sl.Conn)
		if err != nil {
			log.Printf("WARN : Could not stop slave on server %s, %s", sl.URL, err)
		}
		_, err = sl.Conn.Exec(cm)
		if err != nil {
			log.Printf("ERROR: Change master failed on slave %s, %s", sl.URL, err)
		}
		err = dbhelper.StartSlave(sl.Conn)
		if err != nil {
			log.Printf("ERROR: could not start slave on server %s, %s", sl.URL, err)
		}
		if *readonly {
			err = dbhelper.SetReadOnly(sl.Conn, true)
			if err != nil {
				log.Printf("ERROR: Could not set slave %s as read-only, %s", sl.URL, err)
			}
		}
	}
	if *postScript != "" {
		log.Printf("INFO : Calling post-failover script")
		out, err := exec.Command(*postScript, master.Host, newMaster.Host).CombinedOutput()
		if err != nil {
			log.Println("ERROR:", err)
		}
		log.Println("INFO : Post-failover script complete", string(out))
	}
	log.Println("INFO : Failover complete")
	return newMaster.URL, key
}
Exemplo n.º 4
0
/* Triggers a master switchover. Returns the new master's URL */
func (master *ServerMonitor) switchover() (string, int) {
	logprint("INFO : Starting switchover")
	// Phase 1: Cleanup and election
	logprintf("INFO : Flushing tables on %s (master)", master.URL)
	err := dbhelper.FlushTablesNoLog(master.Conn)
	if err != nil {
		logprintf("WARN : Could not flush tables on master", err)
	}
	logprint("INFO : Checking long running updates on master")
	if dbhelper.CheckLongRunningWrites(master.Conn, 10) > 0 {
		logprint("ERROR: Long updates running on master. Cannot switchover")
		return "", -1
	}
	logprint("INFO : Electing a new master")
	var nmUrl string
	key := master.electCandidate(slaves)
	if key == -1 {
		return "", -1
	}
	nmUrl = slaves[key].URL
	logprintf("INFO : Slave %s has been elected as a new master", nmUrl)
	newMaster, err := newServerMonitor(nmUrl)
	if *preScript != "" {
		logprintf("INFO : Calling pre-failover script")
		out, err := exec.Command(*preScript, master.Host, newMaster.Host).CombinedOutput()
		if err != nil {
			logprint("ERROR:", err)
		}
		logprint("INFO : Pre-failover script complete:", string(out))
	}
	// Phase 2: Reject updates and sync slaves
	master.freeze()
	logprintf("INFO : Rejecting updates on %s (old master)", master.URL)
	err = dbhelper.FlushTablesWithReadLock(master.Conn)
	if err != nil {
		logprintf("WARN : Could not lock tables on %s (old master) %s", master.URL, err)
	}
	logprint("INFO : Switching master")
	logprint("INFO : Waiting for candidate master to synchronize")
	masterGtid := dbhelper.GetVariableByName(master.Conn, "GTID_BINLOG_POS")
	if *verbose {
		logprintf("DEBUG: Syncing on master GTID Current Pos [%s]", masterGtid)
		master.log()
	}
	dbhelper.MasterPosWait(newMaster.Conn, masterGtid)
	if *verbose {
		logprint("DEBUG: MASTER_POS_WAIT executed.")
		newMaster.log()
	}
	// Phase 3: Prepare new master
	logprint("INFO : Stopping slave thread on new master")
	err = dbhelper.StopSlave(newMaster.Conn)
	if err != nil {
		logprint("WARN : Stopping slave failed on new master")
	}
	// Call post-failover script before unlocking the old master.
	if *postScript != "" {
		logprintf("INFO : Calling post-failover script")
		out, err := exec.Command(*postScript, master.Host, newMaster.Host).CombinedOutput()
		if err != nil {
			logprint("ERROR:", err)
		}
		logprint("INFO : Post-failover script complete", string(out))
	}
	logprint("INFO : Resetting slave on new master and set read/write mode on")
	err = dbhelper.ResetSlave(newMaster.Conn, true)
	if err != nil {
		logprint("WARN : Reset slave failed on new master")
	}
	err = dbhelper.SetReadOnly(newMaster.Conn, false)
	if err != nil {
		logprint("ERROR: Could not set new master as read-write")
	}
	newGtid := dbhelper.GetVariableByName(master.Conn, "GTID_BINLOG_POS")
	// Insert a bogus transaction in order to have a new GTID pos on master
	err = dbhelper.FlushTables(newMaster.Conn)
	if err != nil {
		logprint("WARN : Could not flush tables on new master", err)
	}
	// Phase 4: Demote old master to slave
	cm := "CHANGE MASTER TO master_host='" + newMaster.IP + "', master_port=" + newMaster.Port + ", master_user='******', master_password='******'"
	logprint("INFO : Switching old master as a slave")
	err = dbhelper.UnlockTables(master.Conn)
	if err != nil {
		logprint("WARN : Could not unlock tables on old master", err)
	}
	dbhelper.StopSlave(master.Conn) // This is helpful because in some cases the old master can have an old configuration running
	_, err = master.Conn.Exec("SET GLOBAL gtid_slave_pos='" + newGtid + "'")
	if err != nil {
		logprint("WARN : Could not set gtid_slave_pos on old master", err)
	}
	_, err = master.Conn.Exec(cm + ", master_use_gtid=slave_pos")
	if err != nil {
		logprint("WARN : Change master failed on old master", err)
	}
	err = dbhelper.StartSlave(master.Conn)
	if err != nil {
		logprint("WARN : Start slave failed on old master", err)
	}
	if *readonly {
		err = dbhelper.SetReadOnly(master.Conn, true)
		if err != nil {
			logprintf("ERROR: Could not set old master as read-only, %s", err)
		}
	}
	// Phase 5: Switch slaves to new master
	logprint("INFO : Switching other slaves to the new master")
	var oldMasterKey int
	for k, sl := range slaves {
		if sl.URL == newMaster.URL {
			slaves[k].URL = master.URL
			oldMasterKey = k
			if *verbose {
				logprintf("DEBUG: New master %s found in slave slice at key %d, reinstancing URL to %s", sl.URL, k, master.URL)
			}
			continue
		}
		logprintf("INFO : Waiting for slave %s to sync", sl.URL)
		dbhelper.MasterPosWait(sl.Conn, masterGtid)
		if *verbose {
			sl.log()
		}
		logprintf("INFO : Change master on slave %s", sl.URL)
		err := dbhelper.StopSlave(sl.Conn)
		if err != nil {
			logprintf("WARN : Could not stop slave on server %s, %s", sl.URL, err)
		}
		_, err = sl.Conn.Exec("SET GLOBAL gtid_slave_pos='" + newGtid + "'")
		if err != nil {
			logprintf("WARN : Could not set gtid_slave_pos on slave %s, %s", sl.URL, err)
		}
		_, err = sl.Conn.Exec(cm)
		if err != nil {
			logprintf("ERROR: Change master failed on slave %s, %s", sl.URL, err)
		}
		err = dbhelper.StartSlave(sl.Conn)
		if err != nil {
			logprintf("ERROR: could not start slave on server %s, %s", sl.URL, err)
		}
		if *readonly {
			err = dbhelper.SetReadOnly(sl.Conn, true)
			if err != nil {
				logprintf("ERROR: Could not set slave %s as read-only, %s", sl.URL, err)
			}
		}
	}
	logprint("INFO : Switchover complete")
	return newMaster.URL, oldMasterKey
}
func main() {
	var errLog = mysql.Logger(log.New(ioutil.Discard, "", 0))
	mysql.SetLogger(errLog)
	flag.Parse()
	if version == true {
		fmt.Println("MariaDB Replication Manager version", repmgrVersion)
		os.Exit(0)
	}
	if logfile != "" {
		var err error
		logPtr, err = os.Create(logfile)
		if err != nil {
			log.Println("ERROR: Error opening logfile, disabling for the rest of the session.")
			logfile = ""
		}
	}
	// if slaves option has been supplied, split into a slice.
	if hosts != "" {
		hostList = strings.Split(hosts, ",")
	} else {
		log.Fatal("ERROR: No hosts list specified.")
	}
	// validate users.
	if user == "" {
		log.Fatal("ERROR: No master user/pair specified.")
	}
	dbUser, dbPass = splitPair(user)
	if rpluser == "" {
		log.Fatal("ERROR: No replication user/pair specified.")
	}
	rplUser, rplPass = splitPair(rpluser)

	// Check that failover and switchover modes are set correctly.
	if switchover == "" && failover == "" {
		log.Fatal("ERROR: None of the switchover or failover modes are set.")
	}
	if switchover != "" && failover != "" {
		log.Fatal("ERROR: Both switchover and failover modes are set.")
	}
	if !contains(failOptions, failover) && failover != "" {
		log.Fatalf("ERROR: Incorrect failover mode: %s", failover)
	}
	if !contains(switchOptions, switchover) && switchover != "" {
		log.Fatalf("ERROR: Incorrect switchover mode: %s", switchover)
	}
	// Forced failover implies interactive == false
	if failover == "force" && interactive == true {
		interactive = false
	}

	if ignoreSrv != "" {
		ignoreList = strings.Split(ignoreSrv, ",")
	}

	// Create a connection to each host and build list of slaves.
	hostCount := len(hostList)
	servers = make([]*ServerMonitor, hostCount)
	slaveCount := 0
	for k, url := range hostList {
		var err error
		servers[k], err = newServerMonitor(url)
		if verbose {
			log.Printf("DEBUG: Creating new server: %v", servers[k].URL)
		}
		if err != nil {
			if driverErr, ok := err.(*mysql.MySQLError); ok {
				if driverErr.Number == 1045 {
					log.Fatalln("ERROR: Database access denied:", err.Error())
				}
			}
			if verbose {
				log.Println("ERROR:", err)
			}
			log.Printf("INFO : Server %s is dead.", servers[k].URL)
			servers[k].State = stateFailed
			continue
		}
		defer servers[k].Conn.Close()
		if verbose {
			log.Printf("DEBUG: Checking if server %s is slave", servers[k].URL)
		}

		servers[k].refresh()
		if servers[k].UsingGtid != "" {
			if verbose {
				log.Printf("DEBUG: Server %s is configured as a slave", servers[k].URL)
			}
			servers[k].State = stateSlave
			slaves = append(slaves, servers[k])
			slaveCount++
		} else {
			if verbose {
				log.Printf("DEBUG: Server %s is not a slave. Setting aside", servers[k].URL)
			}
			servers[k].State = stateUnconn
		}
	}

	// If no slaves are detected, then bail out
	if len(slaves) == 0 {
		log.Fatal("ERROR: No slaves were detected.")
	}

	// Check that all slave servers have the same master.
	for _, sl := range slaves {
		if sl.hasSiblings(slaves) == false {
			log.Fatalln("ERROR: Multi-master topologies are not yet supported.")
		}
	}

	// Check user privileges on live servers
	for _, sv := range servers {
		if sv.State != stateFailed {
			priv, err := dbhelper.GetPrivileges(sv.Conn, dbUser, sv.Host)
			if err != nil {
				log.Fatalf("ERROR: Error getting privileges for user %s on host %s: %s", dbUser, sv.Host, err)
			}
			if priv.Repl_client_priv == "N" {
				log.Fatalln("ERROR: User must have REPLICATION_CLIENT privilege")
			} else if priv.Repl_slave_priv == "N" {
				log.Fatalln("ERROR: User must have REPLICATION_SLAVE privilege")
			} else if priv.Super_priv == "N" {
				log.Fatalln("ERROR: User must have SUPER privilege")
			}
		}
	}

	// Depending if we are doing a failover or a switchover, we will find the master in the list of
	// dead hosts or unconnected hosts.
	if switchover != "" || failover == "monitor" {
		// First of all, get a server id from the slaves slice, they should be all the same
		sid := slaves[0].MasterServerID
		for k, s := range servers {
			if s.State == stateUnconn {
				if s.ServerID == sid {
					master = servers[k]
					master.State = stateMaster
					if verbose {
						log.Printf("DEBUG: Server %s was autodetected as a master", s.URL)
					}
					break
				}
			}
		}
	} else {
		// Slave master_host variable must point to dead master
		smh := slaves[0].MasterHost
		for k, s := range servers {
			if s.State == stateFailed {
				if s.Host == smh || s.IP == smh {
					master = servers[k]
					master.State = stateMaster
					if verbose {
						log.Printf("DEBUG: Server %s was autodetected as a master", s.URL)
					}
					break
				}
			}
		}
	}
	// Final check if master has been found
	if master == nil {
		if switchover != "" || failover == "monitor" {
			log.Fatalln("ERROR: Could not autodetect a master!")
		} else {
			log.Fatalln("ERROR: Could not autodetect a failed master!")
		}
	}

	for _, sl := range slaves {
		if verbose {
			log.Printf("DEBUG: Checking if server %s is a slave of server %s", sl.Host, master.Host)
		}
		if dbhelper.IsSlaveof(sl.Conn, sl.Host, master.IP) == false {
			log.Printf("WARN : Server %s is not a slave of declared master %s", master.URL, master.Host)
		}
	}

	// Check if preferred master is included in Host List
	ret := func() bool {
		for _, v := range hostList {
			if v == prefMaster {
				return true
			}
		}
		return false
	}
	if ret() == false && prefMaster != "" {
		log.Fatal("ERROR: Preferred master is not included in the hosts option")
	}

	// Do failover or switchover manually, or start the interactive monitor.

	if failover == "force" {
		masterFailover(true)
	} else if switchover != "" && interactive == false {
		masterFailover(false)
	} else {
		err := termbox.Init()
		if err != nil {
			log.Fatalln("Termbox initialization error", err)
		}
		_, termlength = termbox.Size()
		loglen := termlength - 9 - (hostCount * 3)
		tlog = NewTermLog(loglen)
		if failover != "" {
			tlog.Add("Monitor started in failover mode")
		} else {
			tlog.Add("Monitor started in switchover mode")
		}
		termboxChan := newTbChan()
		interval := time.Second
		ticker := time.NewTicker(interval * 1)
		for exit == false {
			select {
			case <-ticker.C:
				display()
			case event := <-termboxChan:
				switch event.Type {
				case termbox.EventKey:
					if event.Key == termbox.KeyCtrlS {
						if master.State != stateFailed || failCount > 0 {
							masterFailover(false)
						} else {
							logprint("ERROR: Master failed, cannot initiate switchover")
						}
					}
					if event.Key == termbox.KeyCtrlF {
						if master.State == stateFailed {
							masterFailover(true)
						} else {
							logprint("ERROR: Master not failed, cannot initiate failover")
						}
					}
					if event.Key == termbox.KeyCtrlD {
						for k, v := range servers {
							logprint("Servers", k, v)
						}
						logprint("Master", master)
						for k, v := range slaves {
							logprint("Slaves", k, v)
						}
					}
					if event.Key == termbox.KeyCtrlR {
						logprint("INFO: Setting slaves read-only")
						for _, sl := range slaves {
							dbhelper.SetReadOnly(sl.Conn, true)
						}
					}
					if event.Key == termbox.KeyCtrlW {
						logprint("INFO: Setting slaves read-write")
						for _, sl := range slaves {
							dbhelper.SetReadOnly(sl.Conn, false)
						}
					}
					if event.Key == termbox.KeyCtrlQ {
						exit = true
					}
				}
				switch event.Ch {
				case 's':
					termbox.Sync()
				}
			}
			if master.State == stateFailed && interactive == false {
				rem := (failoverTs + failtime) - time.Now().Unix()
				if (failtime == 0) || (failtime > 0 && (rem <= 0 || failoverCtr == 0)) {
					masterFailover(true)
					if failoverCtr == faillimit {
						exitMsg = "INFO : Failover limit reached. Exiting on failover completion."
						exit = true
					}
				} else if failtime > 0 && rem%10 == 0 {
					logprintf("WARN : Failover time limit enforced. Next failover available in %d seconds.", rem)
				}
			}
		}
		termbox.Close()
		if exitMsg != "" {
			log.Println(exitMsg)
		}
	}
}
Exemplo n.º 6
0
/* Triggers a master switchover. Returns the new master's URL */
func masterFailover(fail bool) {
	logprint("INFO : Starting master switch")
	// Phase 1: Cleanup and election
	var err error
	if fail == false {
		logprintf("INFO : Flushing tables on %s (master)", master.URL)
		err = dbhelper.FlushTablesNoLog(master.Conn)
		if err != nil {
			logprintf("WARN : Could not flush tables on master", err)
		}
		logprint("INFO : Checking long running updates on master")
		if dbhelper.CheckLongRunningWrites(master.Conn, 10) > 0 {
			logprint("ERROR: Long updates running on master. Cannot switchover")
			return
		}
	}
	logprint("INFO : Electing a new master")
	key := master.electCandidate(slaves)
	if key == -1 {
		return
	}
	logprintf("INFO : Slave %s [%d] has been elected as a new master", slaves[key].URL, key)
	// Shuffle the server list
	oldMaster := master
	var skey int
	for k, server := range servers {
		if slaves[key].URL == server.URL {
			skey = k
			break
		}
	}
	master = servers[skey]
	master.State = stateMaster
	slaves[key].delete(&slaves)
	// Call pre-failover script
	if preScript != "" {
		logprintf("INFO : Calling pre-failover script")
		out, err := exec.Command(preScript, oldMaster.Host, master.Host).CombinedOutput()
		if err != nil {
			logprint("ERROR:", err)
		}
		logprint("INFO : Pre-failover script complete:", string(out))
	}
	// Phase 2: Reject updates and sync slaves
	if fail == false {
		oldMaster.freeze()
		logprintf("INFO : Rejecting updates on %s (old master)", oldMaster.URL)
		err = dbhelper.FlushTablesWithReadLock(oldMaster.Conn)
		if err != nil {
			logprintf("WARN : Could not lock tables on %s (old master) %s", oldMaster.URL, err)
		}
	}
	logprint("INFO : Switching master")
	if fail == false {
		logprint("INFO : Waiting for candidate Master to synchronize")
		oldMaster.refresh()
		if verbose {
			logprintf("DEBUG: Syncing on master GTID Binlog Pos [%s]", oldMaster.BinlogPos)
			oldMaster.log()
		}
		dbhelper.MasterPosWait(master.Conn, oldMaster.BinlogPos)
		if verbose {
			logprint("DEBUG: MASTER_POS_WAIT executed.")
			master.log()
		}
	}
	// Phase 3: Prepare new master
	logprint("INFO : Stopping slave thread on new master")
	err = dbhelper.StopSlave(master.Conn)
	if err != nil {
		logprint("WARN : Stopping slave failed on new master")
	}
	// Call post-failover script before unlocking the old master.
	if postScript != "" {
		logprintf("INFO : Calling post-failover script")
		out, err := exec.Command(postScript, oldMaster.Host, master.Host).CombinedOutput()
		if err != nil {
			logprint("ERROR:", err)
		}
		logprint("INFO : Post-failover script complete", string(out))
	}
	logprint("INFO : Resetting slave on new master and set read/write mode on")
	err = dbhelper.ResetSlave(master.Conn, true)
	if err != nil {
		logprint("WARN : Reset slave failed on new master")
	}
	err = dbhelper.SetReadOnly(master.Conn, false)
	if err != nil {
		logprint("ERROR: Could not set new master as read-write")
	}
	cm := "CHANGE MASTER TO master_host='" + master.IP + "', master_port=" + master.Port + ", master_user='******', master_password='******'"
	if fail == false {
		// Get latest GTID pos
		oldMaster.refresh()
		// Insert a bogus transaction in order to have a new GTID pos on master
		err = dbhelper.FlushTables(master.Conn)
		if err != nil {
			logprint("WARN : Could not flush tables on new master", err)
		}
		// Phase 4: Demote old master to slave
		logprint("INFO : Switching old master as a slave")
		err = dbhelper.UnlockTables(oldMaster.Conn)
		if err != nil {
			logprint("WARN : Could not unlock tables on old master", err)
		}
		dbhelper.StopSlave(oldMaster.Conn) // This is helpful because in some cases the old master can have an old configuration running
		_, err = oldMaster.Conn.Exec("SET GLOBAL gtid_slave_pos='" + oldMaster.BinlogPos + "'")
		if err != nil {
			logprint("WARN : Could not set gtid_slave_pos on old master", err)
		}
		_, err = oldMaster.Conn.Exec(cm + ", master_use_gtid=slave_pos")
		if err != nil {
			logprint("WARN : Change master failed on old master", err)
		}
		err = dbhelper.StartSlave(oldMaster.Conn)
		if err != nil {
			logprint("WARN : Start slave failed on old master", err)
		}
		if readonly {
			err = dbhelper.SetReadOnly(oldMaster.Conn, true)
			if err != nil {
				logprintf("ERROR: Could not set old master as read-only, %s", err)
			}
		}
		// Add the old master to the slaves list
		oldMaster.State = stateSlave
		slaves = append(slaves, oldMaster)
	}
	// Phase 5: Switch slaves to new master
	logprint("INFO : Switching other slaves to the new master")
	for _, sl := range slaves {
		if fail == false {
			logprintf("INFO : Waiting for slave %s to sync", sl.URL)
			dbhelper.MasterPosWait(sl.Conn, oldMaster.BinlogPos)
			if verbose {
				sl.log()
			}
		}
		logprint("INFO : Change master on slave", sl.URL)
		err := dbhelper.StopSlave(sl.Conn)
		if err != nil {
			logprintf("WARN : Could not stop slave on server %s, %s", sl.URL, err)
		}
		if fail == false {
			_, err = sl.Conn.Exec("SET GLOBAL gtid_slave_pos='" + oldMaster.BinlogPos + "'")
			if err != nil {
				logprintf("WARN : Could not set gtid_slave_pos on slave %s, %s", sl.URL, err)
			}
		}
		_, err = sl.Conn.Exec(cm)
		if err != nil {
			logprintf("ERROR: Change master failed on slave %s, %s", sl.URL, err)
		}
		err = dbhelper.StartSlave(sl.Conn)
		if err != nil {
			logprintf("ERROR: could not start slave on server %s, %s", sl.URL, err)
		}
		if readonly {
			err = dbhelper.SetReadOnly(sl.Conn, true)
			if err != nil {
				logprintf("ERROR: Could not set slave %s as read-only, %s", sl.URL, err)
			}
		}
	}
	if postScript != "" {
		logprintf("INFO : Calling post-failover script")
		out, err := exec.Command(postScript, oldMaster.Host, master.Host).CombinedOutput()
		if err != nil {
			logprint("ERROR:", err)
		}
		logprint("INFO : Post-failover script complete", string(out))
	}
	logprintf("INFO : Master switch on %s complete", master.URL)
	failCount = 0
	if fail == true {
		failoverCtr++
		failoverTs = time.Now().Unix()
	}
	return
}