Introduction to MHA:

(1) Introduction

(2) The software consists of two parts:

(3) How it works:

Experimental environment

master(192.168.13.129)   mha4mysql-node| 
slave1(192.168.13.130)  mha4mysql-node |
slave2(192.168.13.131)   mha4mysql-node |
manager(192.168.13.128)    mha4mysql-manager, mha4mysql-node|

1. Install mysql database on three master-slave servers

#Install compile lazy environment
[root@localhost ~] yum -y install gcc gcc-c++ ncurses ncurses-devel bison perl-Module-Install cmake
[root@localhost ~] mount.cifs //192.168.100.3/mha/mnt ##Mount package
Password for root@//192.168.100.3/mha:    
[root@localhost ~] cd /mnt
[root@localhost mnt] tar zxvf cmake-2.8.6.tar.gz -C /opt   ##Install cmake compiler software
[root@localhost mnt] cd /opt/cmake-2.8.6/
[root@localhost cmake-2.8.6] ./configure   ##To configure
[root@localhost cmake-2.8.6] gmake && gmake install   ##Compile Installation
#Install mysql database
[root@localhost cmake-2.8.6]# cd /mnt
[root@localhost mnt]# tar zxvf mysql-5.6.36.tar.gz -C /opt ##Unzip MySQL
#Compile mysql
[root@localhost mnt]# cd /opt/mysql-5.6.36/
[root@localhost mysql-5.6.36]# cmake -DCMAKE_INSTALL_PREFIX=/usr/local/mysql \
-DDEFAULT_CHARSET=utf8 \     ##Specify Character Set
-DDEFAULT_COLLATION=utf8_general_ci \     ##Specify Character Set Default
-DWITH_EXTRA_CHARSETS=all \  ##Associate all additional character sets
-DSYSCONFDIR=/etc    ##Profile directory
#install
[root@localhost mysql-5.6.36]# make && make install  ##Compile Installation
#Setting environment variables
[root@localhost mysql-5.6.36]# cp support-files/my-default.cnf /etc/my.cnf  ##Copy Profile
[root@localhost mysql-5.6.36]# cp support-files/mysql.server /etc/rc.d/init.d/mysqld 
##Copy startup script
[root@localhost mysql-5.6.36]# chmod +x /etc/rc.d/init.d/mysqld  ##Give Execution Permission
[root@localhost mysql-5.6.36]# chkconfig --add mysqld  ##Add to service management
[root@localhost mysql-5.6.36]# echo "PATH=$PATH:/usr/local/mysql/bin" >> /etc/profile
##Modify environment variables
[root@localhost mysql-5.6.36]# source /etc/profile   ##Refresh Xinhua Ning Variable
#Create mysql database and authorize
[root@localhost mysql-5.6.36]# groupadd mysql   ##Create Group
[root@localhost mysql-5.6.36]# useradd -M -s /sbin/nologin mysql -g mysql  
##Create System User
[root@localhost mysql-5.6.36]# chown -R mysql.mysql /usr/local/mysql  ##Modify Group Owner
[root@localhost mysql-5.6.36]# mkdir -p /data/mysql  ##Create Data Catalog
#Initialize database
[root@localhost mysql-5.6.36]# /usr/local/mysql/scripts/mysql_install_db \
--basedir=/usr/local/mysql \  ##File directory
--datadir=/usr/local/mysql/data \  ##Data directory
--user=mysql   ##user

2, Modify the main configuration file of mysql: /etc/my.cnf, note that the server-id s of the three servers cannot be the same

---Configure the master server:
[root@master mysql-5.6.36]# vim /etc/my.cnf
[mysql]
server-id = 1
#Open Binary Log
log_bin = master-bin
#Allow synchronization from server
log-slave-updates = true

---Configure slave server 1:

[root@slave1 mysql-5.6.36]# vim /etc/my.cnf
[mysql]
server-id = 2
#Open Binary Log
log_bin = master-bin
 #Synchronize using relay logs
relay-log = relay-log-bin
relay-log-index = slave-relay-bin.index

---Configure slave server 2:
[root@slave2 mysql-5.6.36]# vim /etc/my.cnf
[mysql]
server-id = 3
log_bin = master-bin
relay-log = relay-log-bin
relay-log-index = slave-relay-bin.index

3, three servers start mysql service

#Create two soft links on three servers
[root@master mysql-5.6.36]# ln -s /usr/local/mysql/bin/mysql /usr/sbin/
[root@master mysql-5.6.36]# ln -s /usr/local/mysql/bin/mysqlbinlog /usr/sbin/

#mysql start
[root@master mysql-5.6.36]# /usr/local/mysql/bin/mysqld_safe --user=mysql &
#Turn off firewalls and security features
[root@master mysql-5.6.36]# systemctl stop firewalld.service
[root@master mysql-5.6.36]# setenforce 0

4. Configure Mysql master-slave synchronization (one master-two slave) to authorize two users on all database nodes

[root@master mysql-5.6.36]# Mysql-u root-p //Enter database
mysql> grant replication slave on *.* to 'myslave'@'192.168.13.%' identified by '123';
##Synchronize user myslave from database
mysql> grant all privileges on *.* to 'mha'@'192.168.13.%' identified by 'manager';
##manager uses monitoring users
mysql> flush privileges;  //Refresh Database
#Add the following authorizations (not required in theory) to the database as hostname authorizations (checked by MHA as hostname)
mysql> grant all privileges on *.* to 'mha'@'master' identified by 'manager';
mysql> grant all privileges on *.* to 'mha'@'slave1' identified by 'manager';
mysql> grant all privileges on *.* to 'mha'@'slave2' identified by 'manager';

5. View binaries and synchronization points on master server

mysql> show master status;
+-------------------+----------+--------------+------------------+-------------------+
| File              | Position | Binlog_Do_DB | Binlog_Ignore_DB | Executed_Gtid_Set |
+-------------------+----------+--------------+------------------+-------------------+
| master-bin.000001 |     1213 |              |                  |                   |
+-------------------+----------+--------------+------------------+-------------------+
1 row in set (0.00 sec)

6, set up synchronization on two slave servers

#Synchronize the logs of the primary server by executing the following commands on both slave servers
mysql>  change master to master_host='192.168.13.129',master_user='myslave',master_password='123',master_log_file='master-bin.000001',master_log_pos=1213;
mysql>  start slave;    //Open slave
mysql> show slave status\G;  //View slave
             Slave_IO_Running: Yes
            Slave_SQL_Running: Yes
mysql> set global read_only=1;
mysql> flush privileges;   //Refresh Database

7. Install the MHA lazy environment on all servers, first install the epel source

[root@master mysql-5.6.36]# yum install epel-release --nogpgcheck -y  ##Installation Source
[root@master mysql-5.6.36]# yum install -y perl-DBD-MySQL \  ##For MySQL
perl-Config-Tiny \  ##configuration file
perl-Log-Dispatch \   ##Journal
perl-Parallel-ForkManager \  ##Multithread Management
perl-ExtUtils-CBuilder \    ##Extension Tools
perl-ExtUtils-MakeMaker \  
perl-CPAN  ##Library

8, install node on all servers

#Unzip Install node
[root@manager ~]# cd ~
[root@manager ~]# tar zxvf /mnt/mha4mysql-node-0.57.tar.gz
[root@manager ~]# cd mha4mysql-node-0.57/
[root@manager mha4mysql-node-0.57]# perl Makefile.PL  ##Compile perl
[root@manager mha4mysql-node-0.57]# make && make install  ##Compile Installation

9, install manager on the manger server (note: you must install the node component to install the manager component)

#Close Firewall
[root@manager ~]# systemctl stop firewalld.service 
[root@manager ~]# setenforce 0
#Unzip and install manager
[root@manager ~]# cd ~
[root@manager ~]# tar zxvf /mnt/mha4mysql-manager-0.57.tar.gz
[root@manager ~]# cd mha4mysql-manager-0.57/
[root@manager mha4mysql-manager-0.57]# perl Makefile.PL   ##perl compilation
[root@manager mha4mysql-manager-0.57]# make && make install   ##Compile Installation

Several tools are generated under the usr/local/bin directory after the manager server is installed:

 - masterha_check_repl checks mysql replication status
 - masterha_master_monitor checks if master is down
 - masterha_check_ssh Checks the SHH configuration of MHA  
 - masterha_master_switch controls failover
 - masterha_check_status checks the current MHA running state
 - masterha_conf_host adds or deletes configured server information
 - masterha_stop closes manager
 - script for master ha_manager to start Manager

Several scripts that will be generated under/usr/local/bin after node installation (usually triggered by MHA Manager scripts, no human action required)

 - apply_diff_relay_logs: Identify differences in relay log events and apply their differences to other slave s;
 - save_binary_logs: Save and copy master's binary logs;
 - filter_mysqlbinlog: Remove unnecessary ROLLBACK events (MHA no longer uses this tool);
 - purge_relay_logs: Clears relay logs (does not block SQL threads);

10, Configure Password-Free Access

##Configure password-free authentication for all database nodes in manager
[root@manager ~]# ssh-keygen -t rsa  ##Generate key
Enter file in which to save the key (/root/.ssh/id_rsa):   ##Enter
Enter passphrase (empty for no passphrase):   ##Enter
Enter same passphrase again:    ##Enter
[root@manager ~]# ssh-copy-id 192.168.13.129  ##Upload to another server
Are you sure you want to continue connecting (yes/no)? yes
root@192.168.13.129's password:    ##Enter the password for the 129 server
[root@manager ~]# ssh-copy-id 192.168.13.130
[root@manager ~]# ssh-copy-id 192.168.13.131
##Password-free authentication configured on master to database nodes slave1 and slave2
[root@master ~]# ssh-keygen -t rsa
[root@master ~]# ssh-copy-id 192.168.13.130
[root@master ~]# ssh-copy-id 192.168.13.131
##Password-free authentication configured on slave1 to database nodes master'and slave2
[root@slave1 ~]# ssh-keygen -t rsa
[root@slave1 ~]# ssh-copy-id 192.168.13.129
[root@slave1 ~]# ssh-copy-id 192.168.13.131
##Password-free authentication configured to database nodes slave1 and master on slave2
[root@slave2 ~]# ssh-keygen -t rsa
[root@slave2 ~]# ssh-copy-id 192.168.13.129
[root@slave2 ~]# ssh-copy-id 192.168.13.130

11, Configure MHA, copy relevant scripts to the / usr/local directory on the manager node, and configure

[root@manager ~]# cp -ra /root/mha4mysql-manager-0.57/samples/scripts/ /usr/local/bin/
##Copy script to/usr/local
[root@manager ~]# ls mha4mysql-manager-0.57/samples/scripts/
 ##Generate four executable scripts
 master_ip_failover: When switching automatically VIP Managed scripts;
 master_ip_online_change: When switching Online VIP Management;
 power_manager: The script to shut down the host after a failure occurs;
 send_report: A script to send an alarm after failover;
##Copy the VIP-managed script for auto-switch to/usr/local/bin/directory:
[root@manager ~]# cp /usr/local/bin/scripts/master_ip_failover /usr/local/bin/
[root@manager ~]# vim /usr/local/bin/master_ip_failover   
##Delete everything and rewrite the master_ip_failover script
#!/usr/bin/env perl
use strict;
use warnings FATAL => 'all';

use Getopt::Long;

my (
$command, $ssh_user, $orig_master_host, $orig_master_ip,
$orig_master_port, $new_master_host, $new_master_ip, $new_master_port
);
my $vip = '192.168.13.100';
my $brdc = '192.168.13.255';
my $ifdev = 'ens33';
my $key = '1';
my $ssh_start_vip = "/sbin/ifconfig ens33:$key $vip";
my $ssh_stop_vip = "/sbin/ifconfig ens33:$key down";
my $exit_code = 0;
#my $ssh_start_vip = "/usr/sbin/ip addr add $vip/24 brd $brdc dev $ifdev label $ifdev:$key;/usr/sbin/arping -q -A -c 1 -I $ifdev $vip;iptables -F;";
#my $ssh_stop_vip = "/usr/sbin/ip addr del $vip/24 dev $ifdev label $ifdev:$key";
GetOptions(
'command=s' => \$command,
'ssh_user=s' => \$ssh_user,
'orig_master_host=s' => \$orig_master_host,
'orig_master_ip=s' => \$orig_master_ip,
'orig_master_port=i' => \$orig_master_port,
'new_master_host=s' => \$new_master_host,
'new_master_ip=s' => \$new_master_ip,
'new_master_port=i' => \$new_master_port,
);

exit &main();

sub main {

print "\n\nIN SCRIPT TEST====$ssh_stop_vip==$ssh_start_vip===\n\n";

if ( $command eq "stop" || $command eq "stopssh" ) {

my $exit_code = 1;
eval {
print "Disabling the VIP on old master: $orig_master_host \n";
&stop_vip();
$exit_code = 0;
};
if ($@) {
warn "Got Error: $@\n";
exit $exit_code;
}
exit $exit_code;
}
elsif ( $command eq "start" ) {

my $exit_code = 10;
eval {
print "Enabling the VIP - $vip on the new master - $new_master_host \n";
&start_vip();
$exit_code = 0;
};
if ($@) {
warn $@;
exit $exit_code;
}
exit $exit_code;
}
elsif ( $command eq "status" ) {
print "Checking the Status of the script.. OK \n";
exit 0;
}
else {
&usage();
exit 1;
}
}
sub start_vip() {
`ssh $ssh_user\@$new_master_host \" $ssh_start_vip \"`;
}
# A simple system call that disable the VIP on the old_master
sub stop_vip() {
`ssh $ssh_user\@$orig_master_host \" $ssh_stop_vip \"`;
}

sub usage {
print
"Usage: master_ip_failover --command=start|stop|stopssh|status --orig_master_host=host --orig_master_ip=ip --orig_master_port=port --new_master_host=host --new_master_ip=ip --new_master_port=port\n";
}

12, create the MHA software directory on the manager node and copy the configuration file

[root@manager ~]# mkdir /etc/masterha
[root@manager ~]# cp /root/mha4mysql-manager-0.57/samples/conf/app1.cnf /etc/masterha/
#Edit Profile
[root@manager ~]# vim /etc/masterha/app1.cnf
[server default]
#manager Profile
manager_log=/var/log/masterha/app1/manager.log     
#manager log
manager_workdir=/var/log/masterha/app1
#Master saves the binlog in the same location as the bilog configured in master
master_binlog_dir=/usr/local/mysql/data
#Set the switch script for automatic failover.That's the script above
master_ip_failover_script=/usr/local/bin/master_ip_failover
#Set switch script for manual switch
master_ip_online_change_script=/usr/local/bin/master_ip_online_change
#This password is the one you created earlier to monitor users
password=manager
remote_workdir=/tmp
#Set Replication User Password
repl_password=123
#Set up users for replication users
repl_user=myslave
#Set script to alert when a switch occurs
secondary_check_script=/usr/local/bin/masterha_secondary_check -s 192.168.13.130 -s 192.168.13.131
#Set Up Failure Shutdown Failure Script Host
shutdown_script=""
#Set ssh login user name
ssh_user=root
#Set up monitoring users
user=mha

[server1]
hostname=192.168.13.129
port=3306

[server2]
candidate_master=1
#Set as candidate master, if this parameter is set, the sender master slave will be upgraded from the library to the master library after the sender slave switch
hostname=192.168.13.130
check_repl_delay=0
port=3306

[server3]
hostname=192.168.13.131
port=3306

13, test ssh passwordless authentication, if normal will eventually output success, check build health

[root@manager ~]# masterha_check_ssh -conf=/etc/masterha/app1.cnf
....
[root@manager ~]# masterha_check_repl -conf=/etc/masterha/app1.cnf

14, configure virtual ip on master

[root@master mha4mysql-node-0.57]# /sbin/ifconfig ens33:1 192.168.13.100/24

15, start mha on manager server

[root@manager scripts]# nohup masterha_manager --conf=/etc/masterha/app1.cnf --remove_dead_master_conf --ignore_last_failover < /dev/null > /var/log/masterha/app1/manager.log 2>&1 &
##Looking at the MHA status, you can see that the current master is a mysql node
[root@manager scripts]# masterha_check_status --conf=/etc/masterha/app1.cnf
app1 (pid:43036) is running(0:PING_OK), master:192.168.13.129

16, Fault Simulation

[root@manager scripts]# tailf /var/log/masterha/app1/manager.log   
##Start Monitoring Observation Logging

##Turn off master server
[root@master mha4mysql-node-0.57]# pkill -9 mysql

You can see the state of the slave library, and vip switches to one of the slave libraries:

[root@slave1 mha4mysql-node-0.57]# ifconfig 
ens33: flags=4163<UP,BROADCAST,RUNNING,MULTICAST>  mtu 1500
                inet 192.168.13.130  netmask 255.255.255.0  broadcast 192.168.13.255

ens33:1: flags=4163<UP,BROADCAST,RUNNING,MULTICAST>  mtu 1500
                inet 192.168.13.100  netmask 255.255.255.0  broadcast 192.168.13.255
                ether 00:0c:29:af:94:06  txqueuelen 1000  (Ethernet)

At this point, mysql is installed on the manager, and the client can also connect to the database via virtual ip:

##Take ownership on vip's database server
mysql> grant all on *.* to 'root'@'%' identified by 'abc123';
Query OK, 0 rows affected (0.00 sec)
##Log on with virtual ip on the client
[root@manager ~]# mysql -uroot -h 192.168.13.100 -p  ##Specify virtual ip
Enter password:   ##Input password

MySQL [(none)]> 

Thank you for reading!