keepalived 双机热备

目前项目已经采用nginx来实现负载均衡，但是nginx调度器只有一台，上次还意外的down机一次，导致整个服务应用全部瘫痪，这次准备再加一个调度器来实现站点高可用性，也就是常说的双机热备了。

master: 192.168.1.241
backup: 192.168.1.242
漂移IP：192.168.1.243


1，主备调度器都安装keepalived软件
安装过程如下：

./configure --prefix=/usr/local/keepalived && make && make install
cp /usr/local/keepalived/etc/rc.d/init.d/keepalived /etc/rc.d/init.d/
cp /usr/local/keepalived/etc/sysconfig/keepalived /etc/sysconfig/

mkdir /etc/keepalived
cp /usr/local/keepalived/etc/keepalived/keepalived.conf /etc/keepalived/
cp /usr/local/keepalived/sbin/keepalived /usr/sbin/
service keepalived start

可以先用命令 service keepalived start 启动进行测试，看进程能够启动，注意查看log.

2，主调度器配置如下：

! Configuration File for keepalived

global_defs {
    router_id LVS_DEVEL
}

vrrp_sync_group VG_1 {
    group {
        VI_1
    }
    notify_master /etc/keepalived/sendmail.pl
}

vrrp_instance VI_1 {
    state MASTER
    interface eth0
    virtual_router_id 51
    priority 100
    advert_int 1
    authentication {
        auth_type PASS
        auth_pass 1111
    }
    virtual_ipaddress {
        192.168.1.243
    }
}


2，备调度器配置如下：

! Configuration File for keepalived

global_defs {
   router_id LVS_DEVEL
}

vrrp_sync_group VG_1 {
    group {
    VI_1
    }
    notify_master /etc/keepalived/sendmail.pl
}


vrrp_instance VI_1 {
    state BACKUP
    interface eth0
    virtual_router_id 51
    priority 99
    advert_int 1
    authentication {
        auth_type PASS
        auth_pass 1111
    }
    virtual_ipaddress {
        192.168.1.243
    }
}


3，发送邮件的perl脚本sendmail.pl内容如下：
注意主备发送邮件的标题是不一致的，只要你能识别漂移IP在哪台服务器上即可。

#!/usr/bin/perl -w

use Net::SMTP_auth;
use strict;


my $mailhost = 'smtp.163.com';
my $mailfrom = '[email protected]';
my @mailto   = ('[email protected]');
my $subject  = 'keepalived up on backup';

my $user   = 'test';
my $passwd = 'test';

&SendMail();

##############################
# Send notice mail
##############################
sub SendMail() {

    my $smtp = Net::SMTP_auth->new( $mailhost, Timeout => 120, Debug => 1 )
      or die "Error.\n";
    $smtp->auth( 'LOGIN', $user, $passwd );

    foreach my $mailto (@mailto) {
        $smtp->mail($mailfrom);
        $smtp->to($mailto);
        $smtp->data();
        $smtp->datasend("To: $mailto\n");
        $smtp->datasend("From:$mailfrom\n");
        $smtp->datasend("Subject: $subject\n");
        $smtp->datasend("\n");
        $smtp->dataend();
    }

    $smtp->quit;
}


说明：
a、由于keeplived自带的发送邮件机制是个鸡肋，如果本地不启动25端口就无法实现邮件发送，就琢磨着能不能通过自定义脚本来实现，真的是很幸运，就采用了认证的方式。

b、其他的配置说明就不详细讲了，网上很多资料。


4，测试keepalived
主备调度器都开启80端口，两台服务器上的测试内容不一致，这样更方便测试。