• jimmy Windows 7    4月1日 16:10

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    标签: mysql

    前几天网友来信说帮忙实现这样一个架构:只有两台机器,需要实现其中一台死机之后另一台能接管这台机器的服务,并且在两台机器正常服务时,两台机器都能用上。于是设计了如下的架构。


    此架构主要是由keepalived实现双机高可用,维护了一个外网VIP一个内网VIP。正常情况时,外网VIP和内网VIP都绑定在server1服务器,web请求发送到server1的nginx,nginx对于静态资源请求就直接在本机检索并返回,对于php的动态请求,则负载均衡到server1和server2。对于SQL请求,会将此类请求发送到Atlas MySQL中间件,Atlas接收到请求之后,把涉及写操作的请求发送到内网VIP,读请求操作发送到mysql从,这样就实现了读写分离。

    当主服务器server1宕机时,keepalived检测到后,立即把外网VIP和内网VIP绑定到server2,并把server2的mysql切换成主库。此时由于外网VIP已经转移到了server2,web请求将发送给server2的nginx。nginx检测到server1宕机,不再把请求转发到server1的php-fpm。之后的sql请求照常发送给本地的atlas,atlas把写操作发送给内网VIP,读操作发送给mysql从,由于内网VIP已经绑定到server2了,server2的mysql同时接受写操作和读操作。

    当主服务器server1恢复后,server1的mysql自动设置为从,与server2的mysql主同步。keepalived不抢占server2的VIP,继续正常服务。

    架构要求

    要实现此架构,需要三个条件:

    1、服务器可以设置内网IP,并且设置的内网IP互通;

    2、服务器可以随意绑定IDC分配给我们使用的外网IP,即外网IP没有绑定MAC地址;

    3、MySQL服务器支持GTID,即MySQL-5.6.5以上版本。

    环境说明

    server1

    eth0: 10.96.153.110(对外IP)

    eth1: 192.168.1.100(对内IP)

    server2

    eth0: 10.96.153.114(对外IP)

    eth1: 192.168.1.101(对内IP)

    系统都是CentOS-6。

    对外VIP: 10.96.153.239

    对内VIP: 192.168.1.150

    hosts设置

    /etc/hosts:

    192.168.1.100 server1

    192.168.1.101 server2

    Nginx PHP MySQL Memcached安装

    这几个软件的安装推荐使用EZHTTP来完成。

    解决session共享问题

    php默认的session存储是在/tmp目录下,现在我们是用两台服务器作php请求的负载,这样会造成session分布在两台服务器的/tmp目录下,导致依赖于session的功能不正常。我们可以使用memcached来解决此问题。

    上一步我们已经安装好了memcached,现在只需要配置php.ini来使用memcached,配置如下,打开php.ini配置文件,修改为如下两行的值:

    session.save_handler = memcache

    session.save_path = "tcp://192.168.1.100:11211tcp://192.168.1.101:11211"

    之后重启php-fpm生效。

    Nginx配置

    Server1配置

    http {

    [...]

        upstream php-server {

               server 192.168.1.101:9000;

               server 127.0.0.1:9000;

               keepalive 100;

        }

    [...]

     server {

        [...]

            location ~ \.php$ {

                            fastcgi_pass   php-server;

                            fastcgi_index  index.php;

                            fastcgi_param  script_FILENAME  $document_root$fastcgi_script_name;

                            include        fastcgi_params;

            }

        [...]

     }

    [...]

    }

     

    Server2配置

    http {

    [...]

        upstream php-server {

               server 192.168.1.100:9000;

               server 127.0.0.1:9000;

               keepalive 100;

        }

    [...]

     server {

        [...]

            location ~ \.php$ {

                            fastcgi_pass   php-server;

                            fastcgi_index  index.php;

                            fastcgi_param  script_FILENAME  $document_root$fastcgi_script_name;

                            include        fastcgi_params;

            }

        [...]

     }

    [...]

    }

    这两个配置主要的作用是设置php请求的负载均衡。

    MySQL配置

    mysql util安装

    我们需要安装mysql util里的主从配置工具来实现主从切换。

    cd /tmp

    wget http://dev.mysql.com/get/Downloads/MySQLGUITools/mysql-utilities-1.5.3.tar.gz

    tar xzf mysql-utilities-1.5.3.tar.gz

    cd mysql-utilities-1.5.3

    python setup.py build

    python setup.py install

    mysql my.cnf配置

    server1:

    [mysql]

    [...]

    protocol=tcp

    [...]

    [...]

    [mysqld]

    [...]

    # BINARY LOGGING #

    log-bin = /usr/local/mysql/data/mysql-bin

    expire-logs-days = 14

    binlog-format= row

    log-slave-updates=true

    gtid-mode=on

    enforce-gtid-consistency =true

    master-info-repository=TABLE

    relay-log-info-repository=TABLE

    server-id=1

    report-host=server1

    report-port=3306

    [...]

    server2:

    [mysql]

    [...]

    protocol=tcp

    [...]

    [mysqld]

    [...]

    # BINARY LOGGING #

    log-bin = /usr/local/mysql/data/mysql-bin

    expire-logs-days = 14

    binlog-format= row

    log-slave-updates=true

    gtid-mode=on

    enforce-gtid-consistency =true

    master-info-repository=TABLE

    relay-log-info-repository=TABLE

    server-id=2

    report-host=server2

    report-port=3306

    [...]

    这两个配置主要是设置了binlog和启用gtid-mode,并且需要设置不同的server-id和report-host。

    开放root帐号远程权限

    我们需要在两台mysql服务器设置root帐号远程访问权限。

    mysql> grant all on *.* to 'root'@'192.168.1.%' identified by 'Xp29at5F37' with grant option;

    mysql> grant all on *.* to 'root'@'server1' identified by 'Xp29at5F37' with grant option;

    mysql> grant all on *.* to 'root'@'server2' identified by 'Xp29at5F37' with grant option;

    mysql> flush privileges;

    设置mysql主从

    在任意一台执行如下命令:

    mysqlreplicate --master=root:Xp29at5F37@server1:3306 --slave=root:Xp29at5F37@server2:3306 --rpl-user=rpl:o67DhtaW

    # master on server1: … connected.

    # slave on server2: … connected.

    # Checking for binary logging on master…

    # Setting up replication…

    # …done.

    显示主从关系

    mysqlrplshow --master=root:Xp29at5F37@server1 --discover-slaves-login=root:Xp29at5F37

    # master on server1: … connected.

    # Finding slaves for master: server1:3306

    # Replication Topology Graph

    server1:3306 (MASTER)

    |

    +— server2:3306 – (SLAVE)

    检查主从状态

    mysqlrplcheck --master=root:Xp29at5F37@server1 --slave=root:Xp29at5F37@server2

    # master on server1: … connected.

    # slave on server2: … connected.

    Test Description Status

    —————————————————————————

    Checking for binary logging on master [pass]

    Are there binlog exceptions? [pass]

    Replication user exists? [pass]

    Checking server_id values [pass]

    Checking server_uuid values [pass]

    Is slave connected to master? [pass]

    Check master information file [pass]

    Checking InnoDB compatibility [pass]

    Checking storage engines compatibility [pass]

    Checking lower_case_table_names settings [pass]

    Checking slave delay (seconds behind master) [pass]

    # …done.

    Keepalived配置

    keepalived安装(两台都装)

    yum -y install keepalived

    chkconfig keepalived on

    keepalived配置(server1)

    vi /etc/keepalived/keepalived.conf

    vrrp_sync_group VG_1 {

    group {

    inside_network

    outside_network

    }

    }

     

    vrrp_instance inside_network {

    state BACKUP

    interface eth1

    virtual_router_id 51

    priority 101

    advert_int 1

    authentication {

    auth_type PASS

    auth_pass 3489

    }

    virtual_ipaddress {

    192.168.1.150/24

    }

    nopreempt

    notify /data/sh/mysqlfailover-server1.sh

    }

     

    vrrp_instance outside_network {

    state BACKUP

    interface eth0

    virtual_router_id 50

    priority 101

    advert_int 1

    authentication {

    auth_type PASS

    auth_pass 3489

    }

    virtual_ipaddress {

    10.96.153.239/24

    }

    nopreempt

    }

    keepalived配置(server2)

    vrrp_sync_group VG_1 {

    group {

    inside_network

    outside_network

    }

    }

     

    vrrp_instance inside_network {

    state BACKUP

    interface eth1

    virtual_router_id 51

    priority 100

    advert_int 1

    authentication {

    auth_type PASS

    auth_pass 3489

    }

    virtual_ipaddress {

    192.168.1.150

    }

    notify /data/sh/mysqlfailover-server2.sh

    }

     

    vrrp_instance outside_network {

    state BACKUP

    interface eth0

    virtual_router_id 50

    priority 100

    advert_int 1

    authentication {

    auth_type PASS

    auth_pass 3489

    }

    virtual_ipaddress {

    10.96.153.239/24

    }

    }

    此keepalived配置需要注意的是:

    1、两台server的state都设置为backup,server1增加nopreempt配置,并且server1 priority比server2高,这样用来实现当server1从宕机恢复时,不抢占VIP;

    2、server1设置notify /data/sh/mysqlfailover-server1.shserver2设置notify /data/sh/mysqlfailover-server2.sh作用是自动切换主从

    /data/sh/mysqlfailover-server1.sh脚本内容:

    #!/bin/bash

     

    sleep 10

    state=$3

    result=`mysql -h127.0.0.1 -P3306 -uroot -pXp29at5F37 -e 'show slave status;'`

    [[ "$result" == "" ]] && mysqlState="master" || mysqlState="slave"

     

    if [[ "$state" == "MASTER" ]];then

      if [[ "$mysqlState" == "slave" ]];then

        mysqlrpladmin --slave=root:Xp29at5F37@server1:3306 failover

      fi

     

    elif [[ "$state" == "BACKUP" ]];then

      if [[ "$mysqlState" == "master" ]];then

        mysqlreplicate --master=root:Xp29at5F37@server2:3306 --slave=root:Xp29at5F37@server1:3306 --rpl-user=rpl:o67DhtaW

      fi

    fi

     

    sed -i 's/proxy-read-only-backend-addresses.*/proxy-read-only-backend-addresses = 192.168.1.150:3306/' /usr/local/mysql-proxy/conf/my.cnf

    mysql -h127.0.0.1 -P2345 -uuser -ppwd -e "REMOVE BACKEND 2;"

    /data/sh/mysqlfailover-server2.sh脚本内容:

    #!/bin/bash

     

    sleep 10

    state=$3

    result=`mysql -h127.0.0.1 -P3306 -uroot -pXp29at5F37 -e 'show slave status;'`

    [[ "$result" == "" ]] && mysqlState="master" || mysqlState="slave"

     

    if [[ "$state" == "MASTER" ]];then

      if [[ "$mysqlState" == "slave" ]];then

        mysqlrpladmin --slave=root:Xp29at5F37@server2:3306 failover

      fi

     

    elif [[ "$state" == "BACKUP" ]];then

      if [[ "$mysqlState" == "master" ]];then

        mysqlreplicate --master=root:Xp29at5F37@server1:3306 --slave=root:Xp29at5F37@server2:3306 --rpl-user=rpl:o67DhtaW

      fi

    fi

     

    sed -i 's/proxy-read-only-backend-addresses.*/proxy-read-only-backend-addresses = 192.168.1.150:3306/' /usr/local/mysql-proxy/conf/my.cnf

    mysql -h127.0.0.1 -P2345 -uuser -ppwd -e "REMOVE BACKEND 2;"

    Atlas设置

    atlas安装

    到这里下载最新版本,https://github.com/Qihoo360/Atlas/releases

    cd /tmp

    wget https://github.com/Qihoo360/Atlas/releases/download/2.2.1/Atlas-2.2.1.el6.x86_64.rpm

    rpm -i Atlas-2.2.1.el6.x86_64.rpm

     

    atlas配置

    cd /usr/local/mysql-proxy/conf

    cp test.cnf my.cnf

    vi my.cnf

    调整如下参数,

    proxy-backend-addresses = 192.168.1.150:3306

    proxy-read-only-backend-addresses = 192.168.1.101:3306

    pwds = root:qtyU1btXOo074Itvx0UR9Q==

    event-threads = 8

    注意:

    proxy-backend-addresse设置为内网VIP

    proxy-read-only-backend-addresses设置为server2的IP

    root:qtyU1btXOo074Itvx0UR9Q==设置数据库的用户和密码,密码是通过/usr/local/mysql-proxy/bin/encrypt Xp29at5F37生成。

    更详细参数解释请查看,Atlas配置详解。

     

    启动atlas

    /usr/local/mysql-proxy/bin/mysql-proxy --defaults-file=/usr/local/mysql-proxy/conf/my.cnf

    之后程序里配置mysql就配置127.0.0.1:1234就好。

     

    部署atlas自动维护脚本

    在两台机器都部署此脚本,并添加定时任务(如每2分钟运行一次)我们把脚本放在/data/sh/auto_maintain_atlas.sh脚本内容为:

    #!/bin/bash

     

    count=`mysql -N -h127.0.0.1 -P2345 -uuser -ppwd -e "select * from backends;" | wc -l`

     

    if [[ "$count" == "1" ]];then

      result=`mysql -hserver1 -P3306 -uroot -pXp29at5F37 -e 'show slave status\G'`

      if echo "$result" | grep Slave_IO_State;then

        slaveIP=192.168.1.100

      else

        result=`mysql -hserver2 -P3306 -uroot -pXp29at5F37 -e 'show slave status\G'`

        slaveIP=192.168.1.101

      fi

     

            slaveIORunning=`echo "$result" | awk -F':' '/Slave_IO_Running:/{print $2}'`

            slaveSQLRunning=`echo "$result" | awk -F':' '/Slave_SQL_Running:/{print $2}'`

            SlaveSQLRunning_State=`echo "$result" | awk -F':' '/Slave_SQL_Running_State:/{print $2}'`

        

      if [[ "$slaveIORunning" =~ "Yes" && "$slaveSQLRunning" =~ "Yes" && "$SlaveSQLRunning_State" =~ "Slave has read all relay log" ]];then

        mysql -h127.0.0.1 -P2345 -uuser -ppwd -e "add slave ${slaveIP}:3306;"

      fi

    fi

    为什么需要这个脚本呢?假设目前mysql主服务器在s1s1宕机后,s2接管VIP,接着删除atlas中设置的slave backend,其mysql提升为主。过一段时间后,s1从宕机中恢复,这时候s1的mysql自动切换为从,接着删除atlas中设置的slave backend,开始连接s2的mysql主同步数据。到这个时候我们发现,已经不存在读写分离了,所有的sql都发送给了s2的mysql。auto_maintain_atlas.sh脚本就派上用场了,此脚本会定时的检查主从是否已经同步完成,如果完成就自动增加slave backend,这样读写分离又恢复了,完全不需要人工干预。

     

    server1主宕机测试

     

    测试keepalived是否工作正常

    我们来模拟server1宕机。

    在server1上执行shutdown关机命令。

    此时我们登录server2,执行ip addr命令,输出如下:

    1: lo: mtu 16436 qdisc noqueue state UNKNOWN

    link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00

    inet 127.0.0.1/8 scope host lo

    inet6 ::1/128 scope host

    valid_lft forever preferred_lft forever

    2: eth0: mtu 1500 qdisc pfifo_fast state UP qlen 1000

    link/ether 00:0c:29:81:9d:42 brd ff:ff:ff:ff:ff:ff

    inet 10.96.153.114/24 brd 10.96.153.255 scope global eth0

    inet 10.96.153.239/24 scope global secondary eth0

    inet6 fe80::20c:29ff:fe81:9d42/64 scope link

    valid_lft forever preferred_lft forever

    3: eth1: mtu 1500 qdisc pfifo_fast state UP qlen 1000

    link/ether 00:0c:29:81:9d:4c brd ff:ff:ff:ff:ff:ff

    inet 192.168.1.101/24 brd 192.168.1.255 scope global eth1

    inet 192.168.1.150/32 scope global eth1

    inet6 fe80::20c:29ff:fe81:9d4c/64 scope link

    valid_lft forever preferred_lft forever

    我们看到对外VIP 10.96.153.239和对内IP 192.168.1.150已经转移到server2了,证明keepalived运行正常。

     

    测试是否自动切换了主从

    登录server2的mysql服务器,执行show slave status;命令,如下:

    mysql> show slave status\G

    Empty set (0.00 sec)

    我们发现从状态已经为空,证明已经切换为主了。

     

    测试server1是否抢占VIP

    为什么要测试这个呢?如果server1恢复之后抢占了VIP,而我们的Atlas里后端设置的是VIP,这样server1启动之后,sql的写操作就会向server1的mysql发送,而server1的mysql数据是旧于server2的,所以这样会造成数据不一致,这个是非常重要的测试。

    我们先来启动server1,之后执行ip addr,输出如下:

    1: lo: mtu 16436 qdisc noqueue state UNKNOWN

    link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00

    inet 127.0.0.1/8 scope host lo

    inet6 ::1/128 scope host

    valid_lft forever preferred_lft forever

    2: eth0: mtu 1500 qdisc pfifo_fast state UP qlen 1000

    link/ether 00:0c:29:f1:4f:4e brd ff:ff:ff:ff:ff:ff

    inet 10.96.153.110/24 brd 10.96.153.255 scope global eth0

    inet6 fe80::20c:29ff:fef1:4f4e/64 scope link

    valid_lft forever preferred_lft forever

    3: eth1: mtu 1500 qdisc pfifo_fast state UP qlen 1000

    link/ether 00:0c:29:f1:4f:58 brd ff:ff:ff:ff:ff:ff

    inet 192.168.1.100/24 brd 192.168.1.255 scope global eth1

    inet6 fe80::20c:29ff:fef1:4f58/64 scope link

    valid_lft forever preferred_lft forever

    我们看到,server1并没有抢占VIP,测试正常。不过另人郁闷的是,在虚拟机的环境并没有测试成功,不知道为什么。

     

    测试server2的atlas是否已经删除slave backend

    我们测试这个是为了保证atlas已经没有slave backend,也就是没有从库的设置了,否则当server1恢复时,有可能会把读请求发送给server1的mysql,造成读取了旧数据的问题。

    [root@server1 ~]# mysql -h127.0.0.1 -P2345 -uuser -ppwd

    mysql> select * from backends;

    +————-+——————–+——-+——+

    | backend_ndx | address | state | type |

    +————-+——————–+——-+——+

    | 1 | 192.168.1.150:3306 | up | rw |

    +————-+——————–+——-+——+

    1 rows in set (0.00 sec)

    如果看到只有一个后端,证明运作正常。

     

    测试server1 mysql是否设置为从

    serve1恢复后,登录server1的mysql服务器,执行show slave status;命令,如下:

    mysql> show slave status\G

    *************************** 1. row ***************************

    Slave_IO_State: Opening tables

    Master_Host: server1

    Master_User: rpl

    Master_Port: 3306

    Connect_Retry: 60

    Master_Log_File: mysql-bin.000015

    Read_Master_Log_Pos: 48405991

    Relay_Log_File: mysql-relay-bin.000002

    Relay_Log_Pos: 361

    Relay_Master_Log_File: mysql-bin.000015

    Slave_IO_Running: Yes

    Slave_SQL_Running: yes

     

    测试是否自动恢复读写分离

    server1恢复后一段时间,我们可以看是读写分离是否已经恢复。

    [root@server1 ~]# mysql -h127.0.0.1 -P2345 -uuser -ppwd

    Warning: Using a password on the command line interface can be insecure.

    Welcome to the MySQL monitor. Commands end with ; or \g.

    Your MySQL connection id is 1

    Server version: 5.0.99-agent-admin

    Copyright (c) 2000 2014 Oracle and/or its affiliates. All rights reserved.

    Oracle is a registered trademark of Oracle Corporation and/or its

    affiliates. Other names may be trademarks of their respective

    owners.

    Type ‘help;’ or ‘\h’ for help. Type ‘\c’ to clear the current input statement.

    mysql> select * from backends;

    +————-+——————–+——-+——+

    | backend_ndx | address | state | type |

    +————-+——————–+——-+——+

    | 1 | 192.168.1.150:3306 | up | rw |

    | 2 | 192.168.1.100:3306 | up | ro |

    +————-+——————–+——-+——+

    2 rows in set (0.00 sec)

    我们看到server1已经被添加为slave backend了。这表示已经成功恢复读写分离。

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