This fixes issue #34. Using the wrong hostname.

When registering as a slave we are using the wrong hostname. It should
be our hostname, not the hostname name of the server we are connecting
to.

Fixed issue with using the wrong variable.

Author: gdey

replication/binlogsyncer.go

@@ -3,6 +3,7 @@ package replication
 import (
 	"encoding/binary"
 	"fmt"
+	"os"
 	"sync"
 	"time"
 
@@ -25,10 +26,12 @@ type BinlogSyncer struct {
 	c        *client.Conn
 	serverID uint32
 
-	host     string
-	port     uint16
-	user     string
-	password string
+	// LocalHost is the name of you want to present to the MySQL master. If it is not set it will default to os.Hostname()
+	LocalHost string
+	host      string
+	port      uint16
+	user      string
+	password  string
 
 	masterID uint32
 
@@ -62,6 +65,15 @@ func NewBinlogSyncer(serverID uint32, flavor string) *BinlogSyncer {
 	return b
 }
 
+func (b *BinlogSyncer) LocalHostname() string {
+
+	if b.LocalHost == "" {
+		h, _ := os.Hostname()
+		return h
+	}
+	return b.LocalHost
+}
+
 func (b *BinlogSyncer) Close() {
 	b.m.Lock()
 	defer b.m.Unlock()
@@ -222,11 +234,9 @@ func (b *BinlogSyncer) EnableSemiSync() error {
 	}
 
 	_, err := b.c.Execute(`SET @rpl_semi_sync_slave = 1;`)
-
 	if err != nil {
 		b.semiSyncEnabled = true
 	}
-
 	return errors.Trace(err)
 }
 
@@ -402,7 +412,10 @@ func (b *BinlogSyncer) writeBinlogDumpMariadbGTIDCommand(gset GTIDSet) error {
 func (b *BinlogSyncer) writeRegisterSlaveCommand() error {
 	b.c.ResetSequence()
 
-	data := make([]byte, 4+1+4+1+len(b.host)+1+len(b.user)+1+len(b.password)+2+4+4)
+	hostname := b.LocalHostname()
+
+	// This should be the name of slave host not the host we are connecting to.
+	data := make([]byte, 4+1+4+1+len(hostname)+1+len(b.user)+1+len(b.password)+2+4+4)
 	pos := 4
 
 	data[pos] = COM_REGISTER_SLAVE
@@ -411,9 +424,10 @@ func (b *BinlogSyncer) writeRegisterSlaveCommand() error {
 	binary.LittleEndian.PutUint32(data[pos:], b.serverID)
 	pos += 4
 
-	data[pos] = uint8(len(b.host))
+	// This should be the name of slave hostname not the host we are connecting to.
+	data[pos] = uint8(len(hostname))
 	pos++
-	n := copy(data[pos:], b.host)
+	n := copy(data[pos:], hostname)
 	pos += n
 
 	data[pos] = uint8(len(b.user))