MySQL + Keepalived 實現雙主單活高可用

時間  2020-05-25
標籤 mysql keepalived 實現 可用 欄目 MySQL 简体版
原文   原文鏈接

　　咱們一般說的雙機熱備是指兩臺機器都在運行，但並非兩臺機器都同時在提供服務。當提供服務的一臺出現故障的時候，另一臺會立刻自動接管而且提供服務，並且切換的時間很是短。MySQL雙主複製，即互爲Master-Slave(只有一個Master提供寫操做)，能夠實現數據庫服務器的熱備，可是一個Master宕機後不能實現動態切換。使用Keepalived，能夠經過虛擬IP，實現雙主對外的統一接口以及自動檢查、失敗切換機制，從而實現MySQL數據庫的高可用方案。html

 

1
2
3
4
5
6
Keepalived 保持存活，也就是所謂的高可用或熱備，用來防止單點故障（單點故障是指一旦某一點出現故障就會致使 整個系統架構的不可用現象的發生，那說到keepalived必須說起一個協議VRRP協議，這個協議算是keepalived實現的基礎。
1）Keepalived的工做原理是VRRP（Virtual Router Redundancy Protocol）虛擬路由冗餘協議。在VRRP中有兩組重要的概念：VRRP路由器和虛擬路由器，主控路由器和備份路由器。
2）VRRP路由器是指運行VRRP的路由器，是物理實體，虛擬路由器是指VRRP協議建立的，是邏輯概念。一組VRRP路由器協同工做，共同構成一臺虛擬路由器。
Vrrp中存在着一種選舉機制，用以選出提供服務的路由即主控路由，其餘的則成了備份路由。當主控路由失效後，備份路由中會從新選舉出一個主控路由，來繼 續工做，來保障不間斷服務。

過多內容在這裏就不作詳細介紹了，下面記錄下Mysql+Keepalived雙主熱備的高可用方案的操做記錄mysql

1）先實施Master->Slave的主主同步。主主是數據雙向同步，主從是數據單向同步。通常狀況下，主庫宕機後，須要手動將鏈接切換到從庫上。（可是用keepalived就能夠自動切換）
2）再結合Keepalived的使用，經過VIP實現Mysql雙主對外鏈接的統一接口。即客戶端經過Vip鏈接數據庫；當其中一臺宕機後，VIP會漂移到另外一臺上，這個過程對於客戶端的數據鏈接來講幾乎無感受，從而實現高可用。

1
2
3
4
5
6
7
8
9
10
11
12
13
14
環境描述：
mysql的安裝能夠參考：https://www.cnblogs.com/Camiluo/p/9923030.html
Centos7.6版本
Master1：192.168.49.13        安裝mysql和keepalived
Master2: 192.168.49.128       安裝mysql和keepalived
VIP：166.111.69.10
    
要實現主主同步，能夠先實現主從同步，即master1->master2的主從同步，而後master2->master1的主從同步.
這樣，雙方就完成了主主同步。
 
注意下面幾點：
1）要保證同步服務期間之間的網絡聯通。即能相互ping通，能使用對方受權信息鏈接到對方數據庫（防火牆開放3306端口）。
2）關閉selinux.
3）同步前，雙方數據庫中須要同步的數據要保持一致。這樣，同步環境實現後，再次更新的數據就會如期同步了。
 

 

1、MySQL 主主同步環境部署

一、修改配置文件linux

　　Master 1 的有關複製的配置以下sql

[mysqld] log-bin=mysql-bin server-id=1 log_slave_updates=1

　　Master 2 的有關複製的配置以下數據庫

[mysqld] log-bin=mysql-bin server-id=2 log_slave_updates=1 read_only=1

 

2.建立複製用戶vim

　　Master 1 中建立：centos

CREATE USER 'repl'@'192.168.49.128' IDENTIFIED BY '123';
GRANT REPLICATION SLAVE ON *.* TO 'repl'@'192.168.49.128';

　　Master 2 中建立：bash

CREATE USER 'repl'@'192.168.49.13' IDENTIFIED BY '123';
GRANT REPLICATION SLAVE ON *.* TO 'repl'@'192.168.49.13';

　

3. 執行CHANGE MASTER TO語句服務器

     因是從頭搭建MySQL主從複製集羣，因此不須要獲取全局讀鎖來獲得二進制日誌文件的位置，直接根據show master status的輸出來確認。網絡

    Master1上執行：

(root@localhost) [(none)]> show master status\G
*************************** 1. row ***************************
File: mysql-bin.000009
Position: 2192
Binlog_Do_DB:
Binlog_Ignore_DB:
Executed_Gtid_Set:
1 row in set (0.00 sec)

    Master2上執行：

(root@localhost) [(none)]> show master status\G
*************************** 1. row ***************************
File: mysql-bin.000008
Position: 1574
Binlog_Do_DB: 
Binlog_Ignore_DB: 
Executed_Gtid_Set: 
1 row in set (0.00 sec)

Master 1 上 Change：

CHANGE MASTER TO
  MASTER_HOST='192.168.49.128',
  MASTER_USER='repl',
  MASTER_PASSWORD='123',
  MASTER_LOG_FILE='mysql-bin.000008',
  MASTER_LOG_POS=1574;　

Master 2 上 Change：

CHANGE MASTER TO
  MASTER_HOST='192.168.49.13',
  MASTER_USER='repl',
  MASTER_PASSWORD='123',
  MASTER_LOG_FILE='mysql-bin.000009',
  MASTER_LOG_POS=2192;

 

4.分別在兩個節點上執行start slave 語句，並經過show slave status \G 查看複製是否搭建成功。

成功標準：

Slave_IO_Running: Yes
Slave_SQL_Running: Yes

 

2、配置MySQL + Keepalived 故障轉移的高可用環境

1）安裝keepalived並將其配置成系統服務。

Master1和Master2兩臺機器上一樣進行以下操做：

[root@master1 ~] # yum install -y openssl-devel
[root@master1 ~] # cd /usr/local/src/
[root@master1 src] # wget http://www.keepalived.org/software/keepalived-1.3.5.tar.gz
[root@master1 src] # tar -zvxf keepalived-1.3.5.tar.gz
[root@master1 src] # cd keepalived-1.3.5
[root@master1 keepalived-1.3.5] # ./configure --prefix=/usr/local/keepalived
[root@master1 keepalived-1.3.5] # make && make install
     
[root@master1 keepalived-1.3.5] # cp /usr/local/src/keepalived-1.3.5/keepalived/etc/init.d/keepalived /etc/rc.d/init.d/
[root@master1 keepalived-1.3.5] # cp /usr/local/keepalived/etc/sysconfig/keepalived /etc/sysconfig/
[root@master1 keepalived-1.3.5] # mkdir /etc/keepalived/
[root@master1 keepalived-1.3.5] # cp /usr/local/keepalived/etc/keepalived/keepalived.conf /etc/keepalived/
[root@master1 keepalived-1.3.5] # cp /usr/local/keepalived/sbin/keepalived /usr/sbin/
[root@master1 keepalived-1.3.5] # echo "/etc/init.d/keepalived start" >> /etc/rc.local

2）master1機器上的keepalived.conf配置。（下面配置中沒有使用lvs的負載均衡功能，因此不須要配置虛擬服務器virtual server）

[root@master1 ~] # cp /etc/keepalived/keepalived.conf /etc/keepalived/keepalived.conf.bak
[root@master1 ~] # vim /etc/keepalived/keepalived.conf       ＃清空默認內容，直接採用下面配置： 
vrrp_script chk_mysql {
    script "/etc/keepalived/check_mysql.sh"
    interval 30         #設置檢查間隔時長，可根據本身的需求自行設定
}
vrrp_instance VI_1 {
    state BACKUP        #經過下面的priority來區分MASTER和BACKUP，也只有如此，底下的nopreempt纔有效
    interface eno16777736
    virtual_router_id 51
    priority 100
    advert_int 1
    nopreempt           #防止切換到從庫後，主keepalived恢復後自動切換回主庫
    authentication {
        auth_type PASS
        auth_pass 1111
    }
    track_script {
        chk_mysql
    }
     
    virtual_ipaddress {
        166.111.69.100/24
    }
}

　其中 /etc/keepalived/check_mysql.sh內容以下：　

  
#!/bin/bash
 
###判斷若是上次檢查的腳本還沒執行完，則退出這次執行
if [ `ps -ef|grep -w "$0"|grep -v "grep"|wc -l` -gt 2 ];then
    exit 0
fi 
mysql_con='mysql -uroot -p123456'
error_log="/etc/keepalived/logs/check_mysql.err"
 
###定義一個簡單判斷mysql是否可用的函數
function excute_query {
    ${mysql_con} -e "select 1;" 2>> ${error_log}
}
 
###定義沒法執行查詢，且mysql服務異常時的處理函數
function service_error {
    echo -e "`date "+%F  %H:%M:%S"`    -----mysql service error，now stop keepalived-----" >> ${error_log}
    service keepalived stop &>> ${error_log}
    echo "DB1 keepalived 已中止"|mail -s "DB1 keepalived 已中止,請及時處理！" slowtech@126.com 2>> ${error_log}
    echo -e "\n---------------------------------------------------------\n" >> ${error_log}
}
 
###定義沒法執行查詢,但mysql服務正常的處理函數
function query_error {
    echo -e "`date "+%F  %H:%M:%S"`    -----query error, but mysql service ok, retry after 30s-----" >> ${error_log}
    sleep 30
    excute_query
    if [ $? -ne 0 ];then
        echo -e "`date "+%F  %H:%M:%S"`    -----still can't execute query-----" >> ${error_log}
 
        ###對DB1設置read_only屬性
        echo -e "`date "+%F  %H:%M:%S"`    -----set read_only = 1 on DB1-----" >> ${error_log}
        mysql_con -e "set global read_only = 1;" 2>> ${error_log}
 
        ###kill掉當前客戶端鏈接
        echo -e "`date "+%F  %H:%M:%S"`    -----kill current client thread-----" >> ${error_log}
        rm -f /tmp/kill.sql &>/dev/null
        ###這裏實際上是一個批量kill線程的小技巧
        mysql_con -e 'select concat("kill ",id,";") from  information_schema.PROCESSLIST where command="Query" or command="Execute" into outfile "/tmp/kill.sql";'
        mysql_con -e "source /tmp/kill.sql"
        sleep 2    ###給kill一個執行和緩衝時間
        ###關閉本機keepalived       
        echo -e "`date "+%F  %H:%M:%S"`    -----stop keepalived-----" >> ${error_log}
        service keepalived stop &>> ${error_log}
        echo "DB1 keepalived 已中止"|mail -s "DB1 keepalived 已中止,請及時處理！" slowtech@126.com 2>> ${error_log}
        echo -e "\n---------------------------------------------------------\n" >> ${error_log}
    else
        echo -e "`date "+%F  %H:%M:%S"`    -----query ok after 30s-----" >> ${error_log}
        echo -e "\n---------------------------------------------------------\n" >> ${error_log}
    fi
}
 
###檢查開始: 執行查詢
excute_query
if [ $? -ne 0 ];then
    service mysqld status &>/dev/null
    if [ $? -ne 0 ];then
        service_error
    else
        query_error
    fi
fi

　　經過具體的查詢語句來判斷數據庫服務的可用性，若是查詢失敗，則判斷mysqld進程自己的狀態，若是不正常，則直接中止當前節點的keepalived，將VIP轉移到另一個節點，若是正常，則等待30s，再次執行查詢語句，仍是失敗，則將當前的master節點設置爲read_only，並kill掉當前的客戶端鏈接，而後中止當前的keepalived。

    
 

Master 2

[root@master2 ~]# vim /etc/keepalived/keepalived.conf

! Configuration File for keepalived
 
vrrp_instance VI_1 {
    state BACKUP
    interface eno16777736
    virtual_router_id 51
    priority 90
    advert_int 1
    authentication {
        auth_type PASS
        auth_pass 1111
    }
    notify_master /etc/keepalived/notify_master_mysql.sh    #此條指令告訴keepalived發現本身轉爲MASTER後執行的腳本
    virtual_ipaddress {
        166.111.49.100/24
    }
}

　　其中，/etc/keepalived/notify_master_mysql.sh的內容以下：

#!/bin/bash
###當keepalived監測到本機轉爲MASTER狀態時，執行該腳本
 
change_log=/etc/keepalived/logs/state_change.log
mysql_con='mysql -uroot -p888888'
echo -e "`date "+%F  %H:%M:%S"`   -----keepalived change to MASTER-----" >> $change_log
 
slave_info() {
    ###統必定義一個函數取得slave的position、running、和log_file等信息
    ###根據函數後面所跟參數來決定取得哪些數據
    if [ $1 = slave_status ];then
        slave_stat=`${mysql_con} -e "show slave status\G;"|egrep -w "Slave_IO_Running|Slave_SQL_Running"`
        Slave_IO_Running=`echo $slave_stat|awk '{print $2}'`
        Slave_SQL_Running=`echo $slave_stat|awk '{print $4}'`
    elif [ $1 = log_file -a $2 = pos ];then
        log_file_pos=`${mysql_con} -e "show slave status\G;"|egrep -w "Master_Log_File|Read_Master_Log_Pos|Relay_Master_Log_File|Exec_Master_Log_Pos"`
        Master_Log_File=`echo $log_file_pos|awk '{print $2}'`
        Read_Master_Log_Pos=`echo $log_file_pos|awk '{print $4}'`
        Relay_Master_Log_File=`echo $log_file_pos|awk '{print $6}'`
        Exec_Master_Log_Pos=`echo $log_file_pos|awk '{print $8}'`
    fi
}
 
action() {
    ###經判斷'應該&能夠'切換時執行的動做
    echo -e "`date "+%F  %H:%M:%S"`    -----set read_only = 0 on DB2-----" >> $change_log
 
    ###解除read_only屬性
    ${mysql_con} -e "set global read_only = 0;" 2>> $change_log
 
    echo "DB2 keepalived轉爲MASTER狀態，線上數據庫切換至DB2"|mail -s "DB2 keepalived change to MASTER"\
    slowtech@126.com 2>> $change_log
 
    echo -e "---------------------------------------------------------\n" >> $change_log
}
 
slave_info slave_status
if [ $Slave_SQL_Running = Yes ];then
    i=0    #一個計數器
    slave_info log_file pos
        ###判斷從master接收到的binlog是否所有在本地執行(這樣仍沒法徹底肯定從庫已追上主庫，由於沒法徹底保證io_thread沒有延時(由網絡傳輸問題致使的從庫落後的機率很小)
    until [ $Master_Log_File = $Relay_Master_Log_File -a $Read_Master_Log_Pos = $Exec_Master_Log_Pos ]
     do
        if [ $i -lt 10 ];then    #將等待exec_pos追上read_pos的時間限制爲10s
            echo -e "`date "+%F  %H:%M:%S"`    -----Relay_Master_Log_File=$Relay_Master_Log_File,Exec_Master_Log_Pos=$Exec_Master_Log_Pos is behind Master_Log_File=$Master_Log_File,Read_Master_Log_Pos=$Read_Master_Log_Pos, wait......" >> $change_log    #輸出消息到日誌，等待exec_pos=read_pos
            i=$(($i+1))
            sleep 1
            slave_info log_file pos
        else
            echo -e "The waits time is more than 10s,now force change. Master_Log_File=$Master_Log_File Read_Master_Log_Pos=$Read_Master_Log_Pos Relay_Master_Log_File=$Relay_Master_Log_File Exec_Master_Log_Pos=$Exec_Master_Log_Pos" >> $change_log
            action
            exit 0
        fi
    done
    action 
 
else
    slave_info log_file pos
    echo -e "DB2's slave status is wrong,now force change. Master_Log_File=$Master_Log_File Read_Master_Log_Pos=$Read_Master_Log_Pos Relay_Master_Log_File=$Relay_Master_Log_File Exec_Master_Log_Pos=$Exec_Master_Log_Pos" >> $change_log
    action
fi

　整個腳本的邏輯是讓從的Exec_Master_Log_Pos儘量的追上Read_Master_Log_Pos，它給了10s的限制，若是仍是沒有追上，則直接將master2設置爲主（經過解除read_only屬性），其實這裏面仍是有待商榷的，譬如10s的限制是否合理，仍是必定須要Exec_Master_Log_Pos=Read_Master_Log_Pos才切換。　

DB2上手動切換回DB1的腳本change_to_backup.sh：

#!/bin/bash
###手動執行將主庫切換回DB1的操做
 
mysql_con='mysql -uroot -p123456'
 
echo -e "`date "+%F  %H:%M:%S"`    -----change to BACKUP manually-----" >> /etc/keepalived/logs/state_change.log
echo -e "`date "+%F  %H:%M:%S"`    -----set read_only = 1 on DB2-----" >> /etc/keepalived/logs/state_change.log
$mysql_con -e "set global read_only = 1;" 2>> /etc/keepalived/logs/state_change.log
 
###kill掉當前客戶端鏈接
echo -e "`date "+%F  %H:%M:%S"`    -----kill current client thread-----" >> /etc/keepalived/logs/state_change.log
rm -f /tmp/kill.sql &>/dev/null
###這裏實際上是一個批量kill線程的小技巧
$mysql_con -e 'select concat("kill ",id,";") from  information_schema.PROCESSLIST where command="Query" or command="Execute" into outfile "/tmp/kill.sql";'
$mysql_con -e "source /tmp/kill.sql" 2>> /etc/keepalived/logs/state_change.log
sleep 2    ###給kill一個執行和緩衝時間
 
###確保DB1已經追上了,下面的repl爲複製所用的帳戶，-h後跟DB1的內網IP
log_file_pos=`mysql -urepl -pmysql -h192.168.244.145 -e "show slave status\G;"|egrep -w "Master_Log_File|Read_Master_Log_Pos|Relay_Master_Log_File|Exec_Master_Log_Pos"`
Master_Log_File=`echo $log_file_pos|awk '{print $2}'`
Read_Master_Log_Pos=`echo $log_file_pos|awk '{print $4}'`
Relay_Master_Log_File=`echo $log_file_pos|awk '{print $6}'`
Exec_Master_Log_Pos=`echo $log_file_pos|awk '{print $8}'`
until [ $Read_Master_Log_Pos = $Exec_Master_Log_Pos -a $Master_Log_File = $Relay_Master_Log_File ]
do
    echo -e "`date "+%F  %H:%M:%S"`    -----DB1 Exec_Master_Log_Pos($exec_pos) is behind Read_Master_Log_Pos($read_pos), wait......" >> /etc/keepalived/logs/state_change.log
    sleep 1
done
 
###而後解除DB1的read_only屬性
echo -e "`date "+%F  %H:%M:%S"`    -----set read_only = 0 on DB1-----" >> /etc/keepalived/logs/state_change.log
ssh 192.168.244.145 'mysql -uroot -p123456 -e "set global read_only = 0;" && /etc/init.d/keepalived start' 2>> /etc/keepalived/logs/state_change.log
 
###重啓DB2的keepalived使VIP漂移到DB1
echo -e "`date "+%F  %H:%M:%S"`    -----make VIP move to DB1-----" >> /etc/keepalived/logs/state_change.log
/sbin/service keepalived restart &>> /etc/keepalived/logs/state_change.log
 
echo "DB2 keepalived轉爲BACKUP狀態，線上數據庫切換至DB1"|mail -s "DB2 keepalived change to BACKUP" slowtech@126.com 2>> /etc/keepalived/logs/state_change.log
 
echo -e "--------------------------------------------------\n" >> /etc/keepalived/logs/state_change.log

　Error：在測試過程當中，可能遇到keepalived 啓動失敗的狀況

 

 上面這種狀況是找不到PID 文件而報錯,可手動指定PID文件的位置

查看keepalived.service  

# vi /lib/systemd/system/keepalived.service

[Unit]
Description=LVS and VRRP High Availability Monitor
After=syslog.target network-online.target

[Service]
Type=forking
PIDFile=/usr/local/keepalived/var/run/keepalived.pid
KillMode=process
EnvironmentFile=-/usr/local/keepalived/etc/sysconfig/keepalived
ExecStart=/usr/local/keepalived/sbin/keepalived $KEEPALIVED_OPTIONS
ExecReload=/bin/kill -HUP $MAINPID

[Install]
WantedBy=multi-user.target

發現 PIDFile=/usr/local/keepalived/var/run/keepalived.pid 這個文件的路徑並不存在

[root@centos02_stb keepalived]# find / -name keepalived.pid
/run/keepalived.pid

修改成  /run/keepalived.pid

 運行命令

# systemctl daemon-reload #從新載入 systemd，掃描新的或有變更的單元

再運行就Ok了

service keepalived start
Starting keepalived (via systemctl): [ OK ]
相關文章
相關標籤/搜索
每日一句
    每一个你不满意的现在，都有一个你没有努力的曾经。
本站公眾號
   歡迎關注本站公眾號,獲取更多信息
聯繫我們 最近搜索 最新文章 沪ICP备13005482号-10 MyBatis教程 SQL 教程 MySQL教程 Java 教程 Thymeleaf 教程 Hibernate教程 Spring教程 Redis教程