mysql(三)读写分离与高可用

mysql(三)读写分离与高可用

文章目录

  • mysql(三)读写分离与高可用
    • mysql-proxy实现读写分离
    • mysql高可用之MHA

mysql-proxy实现读写分离

读写分离可以用很多软件实现:mysql-proxy 、MyCat 、Amoeba;我们采用的是mysql-proxy。

用server3来做proxy,12一个读一个写
做实验之前,先做好server1和server2的gtid主从复制
node3

#先关闭之前的mysql,因为proxy也用3306端口
tar zxf mysql-proxy-0.8.5-linux-el6-x86-64bit.tar.gz -C /usr/local
cd /usr/local/
ln -s mysql-proxy-0.8.5-linux-el6-x86-64bit/ mysql-proxy	#软链接便于访问

cd /usr/local/mysql-proxy/bin
./mysql-proxy --help	##查看帮助
./mysql-proxy --help-proxy	##查看proxy的帮助
./mysql-proxy --help-all	##查看所有帮助

cd /usr/local/mysql-proxy
mkdir conf	##建立配置文件目录

#编辑配置文件(自己手动新建)
vim mysql-proxy.conf	

[mysql-proxy]
proxy-address=0.0.0.0:3306
proxy-backend-addresses=172.25.136.1:3306
proxy-read-only-backend-addresses=172.25.136.2:3306
proxy-lua-script=/usr/local/mysql-proxy/share/doc/mysql-proxy/rw-splitting.lua
pid-file=/usr/local/mysql-proxy/log/mysql-proxy.pid
plugins=proxy
log-file=/usr/local/mysql-proxy/log/mysql-proxy.log
log-level=debug
keepalive=true
daemon=true



#创建日志目录
mkdir /usr/local/mysql-proxy/log

#修改lua脚本
min_idle_connections = 1,	##把原来的4和8改为1和2,默认超过4个连接才会启动读写分离,改为1个好测试
max_idle_connections = 2,

#启动mysql-proxy
/usr/local/mysql-proxy/bin/mysql-proxy --defaults-file=/usr/local/mysql-proxy/conf/mysql-proxy.conf


#可能会启动报错:
2019-03-15 14:15:04: (critical) mysql-proxy-cli.c:326: loading config from '/usr/local/mysql-proxy/conf/mysql-proxy.conf' failed: permissions of /usr/local/mysql-proxy/conf/mysql-proxy.conf aren't secure (0660 or stricter required)
2019-03-15 14:15:04: (message) Initiating shutdown, requested from mysql-proxy-cli.c:328
2019-03-15 14:15:04: (message) shutting down normally, exit code is: 1

#因为配置文件权限过大
chmod 660 /usr/local/mysql-proxy/conf/mysql-proxy.conf

再启动,正常

#查看日志
cat /usr/local/mysql-proxy/log/mysql-proxy.log
看到两个节点都加进来了

2019-03-15 15:07:22: (message) chassis-unix-daemon.c:136: [angel] we try to keep PID=2521 alive
2019-03-15 15:07:22: (debug) chassis-unix-daemon.c:157: waiting for 2521
2019-03-15 15:07:22: (debug) chassis-unix-daemon.c:121: we are the child: 2521
2019-03-15 15:07:22: (critical) plugin proxy 0.8.5 started
2019-03-15 15:07:22: (debug) max open file-descriptors = 1024
2019-03-15 15:07:22: (message) proxy listening on port 0.0.0.0:3306
2019-03-15 15:07:22: (message) added read/write backend: 172.25.136.1:3306
2019-03-15 15:07:22: (message) added read-only backend: 172.25.136.2:3306


node1

授权新用户读写权限
mysql> grant insert,update,select on *.* to wsp@'%' identified by 'Wsp+123ld';

mysql> flush privileges;

mysql> use westos;
Database changed
mysql> create table usertb (
    -> username varchar(10) not null,
    -> password varchar(15) not null);

mysql> desc usertb;


此时在另一台机器连接数据库(node3),当连接个数超过两个时,会发生负载均衡
eg:
[root@server3 log]# lsof -i:3306
COMMAND    PID USER   FD   TYPE DEVICE SIZE/OFF NODE NAME
mysql-pro 2521 root   10u  IPv4  28318      0t0  TCP *:mysql (LISTEN)
mysql-pro 2521 root   11u  IPv4  28362      0t0  TCP server3:mysql->foundation0.ilt.example.com:55716 (ESTABLISHED)
mysql-pro 2521 root   12u  IPv4  28363      0t0  TCP server3:47376->server1:mysql (ESTABLISHED)
mysql-pro 2521 root   13u  IPv4  28709      0t0  TCP server3:mysql->foundation0.ilt.example.com:55722 (ESTABLISHED)
mysql-pro 2521 root   14u  IPv4  28710      0t0  TCP server3:47382->server1:mysql (ESTABLISHED)
mysql-pro 2521 root   15u  IPv4  28769      0t0  TCP server3:mysql->foundation0.ilt.example.com:55726 (ESTABLISHED)
mysql-pro 2521 root   16u  IPv4  28770      0t0  TCP server3:55914->server2:mysql (ESTABLISHED)

测试:
在另一台机器上插入数据:
MySQL [(none)]> use westos
Reading table information for completion of table and column names
You can turn off this feature to get a quicker startup with -A
MySQL [westos]> insert into usertb values('user1','123');
MySQL [westos]> select * from usertb;
+----------+----------+
| username | password |
+----------+----------+
| user1    | 123      |
+----------+----------+
1 row in set (0.00 sec)

发现server1和server2都能看到,看不出读写分离,因为存在主从复制

现在到server2上关闭复制
mysql> stop slave;

这时再插入数据
MySQL [westos]> insert into usertb values ('user4','123');
Query OK, 1 row affected (0.01 sec)

MySQL [westos]> select * from usertb;
+----------+----------+
| username | password |
+----------+----------+
| user1    | 123      |
| user2    | 123      |
+----------+----------+
2 rows in set (0.00 sec)

'发现插入的数据看不到,但是在server1上可以看到,这就说明了它在读的时候读的是server2上的数据,而写操作却写在了server1上'

mysql高可用之MHA

写在前面:建议:在做MHA之前 不要和之前的实验混淆 做好gtid复制就好,如果报错,查看主从数据是否同步

MHA是一套相对成熟的MySQL高可用方案,能做到在0~30s内自动完成数据库的故障切换操作,在master服务器不宕机的情况下,基本能保证数据的一致性

node3


关闭server3上的proxy

killall mysql-proxy

#修改server3的配置:
vim /etc/my.cnf

server_id=3
gtid_mode=ON
enforce_gtid_consistency=ON
log_slave_updates=ON
log_bin=binlog

#### 不需要做半同步复制

配置server3
#先删除数据目录中的内容 rm -fr /var/lib/mysql/*

#启动mysqld
systemctl start mysqld

#初始化
mysql_secure_installation

#server3上配置mysql的GTID主从复制
mysql> change master to master_host='172.25.136.1', master_user='repl', master_password='Wsp+123ld', master_auto_position=1;
Query OK, 0 rows affected, 2 warnings (0.04 sec)

mysql> start slave;

#####这里如果出现server3无法同步的情况,怎么解决(1236错误)
先查看gtid执行了多少
mysql> show global variables like '%gtid%';
+----------------------------------+------------------------------------------+
| Variable_name                    | Value                                    |
+----------------------------------+------------------------------------------+
| binlog_gtid_simple_recovery      | ON                                       |
| enforce_gtid_consistency         | ON                                       |
| gtid_executed                    | 1a49d884-4b83-11e9-913f-5254008ec469:1-4 |
| gtid_executed_compression_period | 1000                                     |
| gtid_mode                        | ON                                       |
| gtid_owned                       |                                          |
| gtid_purged                      | 1a49d884-4b83-11e9-913f-5254008ec469:1-4 |
| session_track_gtids              | OFF                                      |
+----------------------------------+------------------------------------------+

gtid_executed表示已经执行了多少,gtid_purged表示执行完清除了二进制日志清除了多少
因为日志已经清除,所以slave节点无法同步数据


先在server1上备份所有数据

mysqldump --all-databases --single-transaction --triggers --routines --events --host=127.0.0.1 --port=3306 --user=root --password=Wsp+123ld > wsp.sql

然后在server3上进行导入

[root@server3 ~]# mysql -p < wsp.sql

会有报错
[root@server3 ~]# mysql -p < wsp.sql 
Enter password: 
ERROR 1840 (HY000) at line 24: @@GLOBAL.GTID_PURGED can only be set when @@GLOBAL.GTID_EXECUTED is empty.

登录数据库,清除原来数据

mysql> stop slave;

mysql> reset master;

再导入,正常

进入数据库,重新配置复制

mysql> CHANGE MASTER TO MASTER_HOST = '172.25.0.1', MASTER_USER = 'repl', MASTER_PASSWORD = 'Wsp+123ld', MASTER_AUTO_POSITION = 1;

mysql> start slave;

主从复制正常

#安装并启用半同步插件  
##其实不需要这步
mysql> INSTALL PLUGIN rpl_semi_sync_master SONAME 'semisync_master.so';

mysql> INSTALL PLUGIN rpl_semi_sync_slave SONAME 'semisync_slave.so';

mysql> SET GLOBAL rpl_semi_sync_slave_enabled =1;

#为了不每次启动数据库都激活插件,写入配置文件(server1 2 3都写,,写在配置文件最后)

vim /etc/my.cnf

rpl_semi_sync_master_enabled=1
rpl_semi_sync_master_timeout=10000000000000000000

rpl_semi_sync_slave_enabled=1

#在server1和server2上都安装半同步插件
mysql> INSTALL PLUGIN rpl_semi_sync_master SONAME 'semisync_master.so';

mysql> INSTALL PLUGIN rpl_semi_sync_slave SONAME 'semisync_slave.so';	##每个节点都安装master和slave插件是因为高可用需要每个节点都可以做master或者slave

#重启io线程使server1和server2同步

#server1和server2都激活半同步插件
mysql> SET GLOBAL rpl_semi_sync_master_enabled =1;

#server2上先不用设置这个
mysql> SET GLOBAL rpl_semi_sync_master_timeout =10000000000000000000;	##半同步超时时间,生产环境应该设置为无穷大,这里这个值是我试出来的最大值,再大就会报错,上课时可以让学生自己试最大值

mysql> show variables like '%rpl%';	##查看

node4
配置高可用

下载mha7相关安装包
在server4上安装:

yum install -y mha4mysql-manager-0.58-0.el7.centos.noarch.rpm 
perl-* mha4mysql-node-0.58-0.el7.centos.noarch.rpm

#配置免密访问(server4需要连接server1 2 3都免密码)
在server4上:
[root@server4 ~]# ssh-keygen	##先生成密钥

[root@server4 ~]# ssh-copy-id server1

[root@server4 ~]# ssh-copy-id server2	#发送密钥

[root@server4 ~]# ssh-copy-id server3

#其他3个节点都安装mha4mysql-node-0.58-0.el7.centos.noarch.rpm即可

#在server4上配置mha工作目录及配置文件
#参考https://www.cnblogs.com/gomysql/p/3675429.html
mkdir /etc/masterha

vim /etc/masterha/app1.cnf

[server default]
manager_workdir=/etc/masterha
manager_log=/var/log/masterha.log  # manager 日志文件
master_binlog_dir=/etc/masterha
#master_ip_failover_script= /usr/local/bin/master_ip_failover
#master_ip_online_change_script= /usr/local/bin/master_ip_online_change
password=Wsp+123ld  #MySQL管理帐号和密码
user=root
ping_interval=1
remote_workdir=/tmp
repl_password=Wsp+123ld
repl_user=repl  # 复制帐号和密码
#report_script=/usr/local/send_report
#secondary_check_script= /usr/local/bin/masterha_secondary_check -s server03 -s server02
#shutdown_script=""
ssh_user=root # 系统ssh用户

[server1]
hostname=172.25.136.1
port=3306

[server2]
hostname=172.25.136.2
port=3306
candidate_master=1
check_repl_delay=0

[server3]
hostname=172.25.136.3
port=3306
no_master=1	##no_master表示这个节点不能作为master


测试


##检测ssh连接
[root@server4 masterha]# masterha_check_ssh --conf=/etc/masterha/app1.cnf

发现报错,server1 2 3互相之间不免密
拷贝server4上的密钥给server1 2 3
scp -r .ssh server1 2 3


接下来检测复制功能
[root@server4 ~]# masterha_check_repl --conf=/etc/masterha/app1.cnf

发现有报错
Fri Mar 22 10:03:45 2019 - [error][/usr/share/perl5/vendor_perl/MHA/Server.pm, ln180] Got MySQL error when connecting 172.25.0.2(172.25.0.2:3306) :1130:Host 'server4' is not allowed to connect to this MySQL server, but this is not a MySQL crash. Check MySQL server settings.

这是因为server4默认是用root远程连接数据库,但是在配置数据库是已经禁用了root的远程连接

在主库(node1)上授权用户
mysql> grant all on *.* to root@'%' identified by 'Wsp+123ld';

再检测发现可能卡住了,因为之前半同步的配置写在了配置文件里,数据不同步就会卡住,在所有节点配置文件里删除半同步配置,只保留之前的
server_id=1
gtid_mode=ON
enforce_gtid_consistency=ON
log_slave_updates=ON
log_bin=binlog
##所有节点的配置文件必须一样!!!!(前面的内容其实都不需要做 只要保持三个server的my.cnf的内容与这里的一致就可以 三台做好gtid的复制就ok )
##而且三个节点必须有数据(数据必须同步)

成功后,再在两个slave节点设置只读(不写在配置文件里,因为slave随时可能切换为master)

#测试manager能否开启
nohup masterha_manager --conf=/etc/masterha/app1.cnf --remove_dead_master_conf --ignore_last_failover < /dev/null > /var/log/masterha.log 2>&1 &
#测试手动failover切换
先关闭manager,不关的话切不了,manager就是自动切换的工具

[root@server4 masterha]# masterha_stop --conf=/etc/masterha/app1.cnf

server1:systemctl stop mysqld
#手动切换

masterha_master_switch --master_state=dead --conf=/etc/masterha/app1.cnf --dead_master_host=172.25.0.1 --dead_master_ip=172.25.0.1 --dead_master_port=3306 --new_master_host=172.25.0.2 --new_master_port=3306
'手动切换之前,需要保证主从同步正常,repl复制用户能够远程连接'

中间都选yes

切换成功后,可以在server3上看到它的master已经变成了server2

再手动开启server1,作为slave加入集群

[root@server1 ~]# systemctl start mysqld

mysql> CHANGE MASTER TO MASTER_HOST = '172.25.0.2', MASTER_USER = 'repl', MASTER_PASSWORD = 'Wsp+123ld', MASTER_AUTO_POSITION = 1;

mysql> start slave;

mysql> show slave status\G

至次完成了一次手动切换

这时会在/etc/masterha目录下生成一个app1.failover.complete文件,是来记录failover情况的,再进行failover时必须先把这个文件删除,不然不会failover


#手动在线切换,刚才是master挂掉后切换
masterha_master_switch --conf=/etc/masterha/app1.cnf --master_state=alive --new_master_host=172.25.13.1 --new_master_port=3306 --orig_master_is_new_slave --running_updates_limit=10000

又切换回node1为master
测试半自动failover
首先清理app1.failover.complete

开启mha manager
[root@server4 masterha]# nohup masterha_manager --conf=/etc/masterha/app1.cnf &>/dev/null &

mha manager自带守护进程

在server1上查看
[root@server1 ~]# ps ax | grep mysql
 2320 ?        Sl     0:00 /usr/sbin/mysqld --daemonize --pid-file=/var/run/mysqld/mysqld.pid
 2366 pts/0    S+     0:00 grep --color=auto mysql

看到mysql的进程

kill -9 2320

再查看,发现mysql进程又开启了
[root@server1 ~]# ps ax | grep mysql
 2400 ?        Sl     0:00 /usr/sbin/mysqld --daemonize --pid-file=/var/run/mysqld/mysqld.pid
 2431 pts/0    S+     0:00 grep --color=auto mysql

在server1上手动关闭mysqld

[root@server1 ~]# systemctl stop mysqld

在server4上查看
[root@server4 masterha]# cat /var/log/masterha.log

发现已经切换,同时manager进程退出,所以全自动需要脚本

先把server1加回集群

mysql> CHANGE MASTER TO MASTER_HOST = '172.25.0.2', MASTER_USER = 'repl', MASTER_PASSWORD = 'Wsp+123ld', MASTER_AUTO_POSITION = 1;

mysql> start slave;
全自动切换配置及测试

#配置脚本和vip漂移
因为用户访问入口只能有一个,所以需要配置vip

编辑master_ip_failover 和 master_ip_online_change 两个脚本
修改内容:

my $ssh_start_vip = "/sbin/ip addr add $vip dev eth0";
my $ssh_stop_vip = "/sbin/ip addr del $vip dev eth0";

配置自动添加和删除vip

cp master_ip_failover master_ip_online_change /usr/local/bin
cd /usr/local/
cd bin/
chmod +x master_ip_failover master_ip_online_change

###注意在server4的配置文件种 这两行的注释要打开
master_ip_failover_script= /usr/local/bin/master_ip_failover
master_ip_online_change_script= /usr/local/bin/master_ip_online_change


#目前server2是master,所以先给server2添加vip

[root@server2 ~]# ip addr add 172.25.0.100/24 dev eth0

测试vip漂移

[root@server4 bin]# masterha_master_switch --conf=/etc/masterha/app1.cnf --master_state=alive --new_master_host=172.25.0.1 --new_master_port=3306 --orig_master_is_new_slave --running_updates_limit=10000
#可以看到切换vip
***************************************************************
Disabling the VIP - 172.25.0.100/24 on old master: 172.25.0.2
***************************************************************


***************************************************************
Enabling the VIP - 172.25.0.100/24 on new master: 172.25.0.1 
***************************************************************

#测试全自动切换
在server4上先删除app1.failover.complete

开启manager

nohup masterha_manager --conf=/etc/masterha/app1.cnf &>/dev/null &

然后在master(server1)上关闭mysql,模拟故障

再在server4上查看日志

cat /var/log/masterha.log
可以看到切换成功,vip也成功漂移

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