#!/usr/bin/env bash
# Name:		MySQL_REBUILD_LIVE_SLAVE_from_MASTER
# Purpose:	Rebuilds live all Databases of a replication SLAVE based on a good running MASTER
#		This rebuilt action is done without stopping the MASTER MySQL server or even locking the tables
#		or the destination server (SLAVE)
# Syntax:	MySQL_REBUILD_LIVE_SLAVE_from_MASTER Master:Port Slave:Port {F|P}
#		eg. MySQL_REBUILD_LIVE_SLAVE_from_MASTER db1:3306 www1:3306 P
#               {F|P} - Dump method     F) Uses a full temporary dump file method     P) Uses the pipe method
#               Note: In some situation where the databases are very big (GB) the Pipe (P) method might not work well
#                     In these case it is recommended to use the File(F) method
# Changes:	05 Dec 2008	First implementation of script
#               10 Oct 2013     Added the File(F) transfer method, added --skip-lock-tables to the dump command, added the manual entry of root PW
# Notes 1:	In the case of using the Dump file method, the file will be transferred via rsync to the slave for importing.
#               Therefore the key of the user running the script must be already installed in slave before running the script
#-----------------------------------------------------------------------------------
# Some constants:
DUMPFILE="/tmp/mydump.sql"
# Resync the databases except the following Databases
EXCEPTIONS="information_schema mysql test"
#
# Functions
# Syntax: testhost addr port. Returns: hostOK=1
testhost () {
    hostOK=0
    if (nmap -n --unprivileged --host-timeout 1600ms --max_rtt_timeout 1600ms -p $2 -P0 $1 2>/dev/null | grep -q "open" &>/dev/null); then
	hostOK=1
    fi
};
#
usage () {
    echo "ERROR: Somethig is wrong with the given arguments"
    echo "Syntax: MySQL_REBUILD_LIVE_SLAVE_from_MASTER Master:Port Slave:port {F|P}"
    echo "    eg. MySQL_REBUILD_LIVE_SLAVE_from_MASTER master1:3306 slave1:3306 P"
    exit 1
}
#
# Check the command syntax
if [ $# -ne 3 ]; then
    usage
fi
#
# Get the mysql root password
read -s -p "Please enter the MySQL root password: " rootpw
#
#- Check the hosts info validity
if ! (echo $1 | grep ':'); then
    echo "ERROR: The 2nd parameter(master) must be the combination 'host:port'"
    exit 3
fi
#
if ! (echo $2 | grep ':'); then
    echo "ERROR: The third parameter must be the combination 'host:port'"
    exit 4
fi
#
method=$3
#
# Check the hosts connectivity of master host
Mhost=$(echo $1 | cut -d: -f1)
Mport=$(echo $1 | cut -d: -f2)
#
testhost $Mhost $Mport
if [ $hostOK = "0" ]; then
    echo "ERROR: The master $Mhost:$Mport does not respond"
    exit 5
fi
#
# Check the hosts connectivity of slave host
#
Shost=$(echo $2 | cut -d: -f1)
Sport=$(echo $2 | cut -d: -f2)
#
testhost $Shost $Sport
if [ $hostOK = "0" ]; then
    echo "ERROR: The slave $Shost:$Sport does not respond"
    exit 6
fi
#
# Stop and reset the slave
echo "STOP SLAVE; RESET SLAVE;" | mysql --host=$Shost --port=$Sport --user=root --password=$rootpw
#
databases=""
for DB in $(echo "show databases;" | mysql --host=$Shost --port=$Sport --user=root --password=$rootpw | grep -v Database) ; do
    # Only delete/add the databases that are not in the Exceptions list
    if ! (echo $EXCEPTIONS | grep -q $DB); then
        # here I was deleting the databases one by one before recreating them in slave
        # I replaced this by the option --add-drop-database in mysqldump
        #echo "Deleting database $DB on Slave $Shost:$Sport"
        #echo "DROP DATABASE $DB;" | mysql -h $Shost --port=$Sport -u root --password=$rootpw
        # Corrected. Thanks to Dorian Kavaja
        if [ "$databases" == "" ]; then
            databases=$DB
        else
            databases="$databases $DB"
        fi
    fi
done
# The following lines is thanks to Dorian Kavaja
#because sometimes the log file on the master was changed before the dump was finished
echo "FLUSH LOGS; RESET MASTER;" | mysql -–host=$Mhost –-port=$Mport --user=root –password=$rootpw
#
# Now do the transfer
# Added “–routines –triggers” to the mysqldump command, so triggers and functions were included in the dump.
# Thanks to Dorian Kavaja
case $method in
    P)	# Transfer all databases from master to slave directly using a pipe(P)
	echo "Transfering the all databases from master $Mhost:$Mport into slave $Shost:$Sport directly"
	mysqldump --host=$Mhost --port=$Mport --user=root --password=$rootpw \
	--single-transaction --flush-logs --master-data=2 --skip-lock-tables \
	--add-drop-database --delete-master-logs --hex-blob –-routines –-triggers --databases $databases \
	| mysql --host=$Shost --port=$Sport --user=root --password=$rootpw
    ;;
#
    F)  # Transfer the databases using a dump file
	echo "Dumping the all databases from master $Mhost:$Mport into file $DUMPFILE"
	mysqldump --host=$Mhost --port=$Mport --user=root --password=$rootpw \
	--single-transaction --flush-logs --master-data=2 --skip-lock-tables \
	--add-drop-database --delete-master-logs --hex-blob –-routines –-triggers --databases $databases > $DUMPFILE
#
	echo "Transferring the dump file $DUMPFILE from Master $Mhost to slave $Shost via compressed rsync"
	rsync -vz $DUMPFILE $Shost:$DMPFILE
	echo "Importing the dump file ($DUMPFILE) into slave MySQL server $Shost"
	ssh $Shost "mysql --host=$Shost --port=$Sport --user=root --password=$rootpw < $DUMPFILE"
    ;;
#
    *) usage ;;
esac
#
# Find out the master binlog file name
masterlogfile=$(echo "SHOW MASTER STATUS\G;" | mysql --host=$Mhost --port=$Mport --user=root --password=$rootpw | grep "File:" | cut -d: -f2 | cut -d" " -f2)
#
# Sync the slave with master binlog position 4
echo "CHANGE MASTER TO master_log_file='$masterlogfile',master_log_pos=4;" | mysql --host=$Shost --port=$Sport --user=root --password=$rootpw
#
# Start the replication on slave
echo "START SLAVE;" | mysql --host=$Shost --port=$Sport --user=root --password=$rootpw
sleep 3
#
# Show slave status to see if all is in sync
echo "SHOW SLAVE STATUS \G;" | mysql --host=$Shost --port=$Sport --user=root --password=$rootpw