keepalived简介及基础配置

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　　一、keepalived简介

　　keepalived是高可用集群的解决方案之一，相比于heartbeat，corosync来说是较为轻量级的。keeoalived是vrrp协议在linux主机上以守护进程方式实现，其优点是能够根据配置文件自动生成ipvs规则，同时相比于LVS，多出了健康状态检测的功能，这是LVS不具备的。
　　keepalived官方架构图如下：

　　

　　（引自keepalived官方文档：http://keepalived.org/）
　　Scheduler：调度器

　　memory mngt：内存空间管理
　　control plane configuretion file parser：配置文件的主控器，类似于Nginx的master进程
　　VRRP Stack：vrrp功能的实现
　　Checkers：健康状态检测
　　WatchDog：监控VRRP进程，并进行守护
　　

　　二、keepalived配置
　　1、集群配置前准备
　　Nginx：192.168.0.104
　　node1：192.168.0.40
1、本机的主机名与hosts中定义的主机保持一致，要与hostname（uname -n）获得的名称保持一致
vim /etc/hosts
192.168.0.104   Nginx
192.168.0.40    node1
2、各节点时间同步
[root@node1 ~]# yum install ntp
[root@node1 ~]# vim /etc/ntp.conf
将下面的语句
restrict default kod nomodify notrap nopeer noquery
修改为
restrict default nomodify
restrict 192.168.0.0 mask 255.255.255.0 nomodify
[root@node1 ~]# service ntpd start
[root@Nginx ~]# ntpdate 192.168.0.40
10 Feb 14:14:50 ntpdate[2214]: adjust time server 192.168.0.40 offset 0.032422 sec
[root@Nginx ~]# date; ssh 192.168.0.40 'date'
2017年 02月 10日 星期五 14:16:21 CST
root@192.168.0.40's password:
2017年 02月 10日 星期五 14:16:24 CST
3、各节点之间密钥认证
1.生成密钥对
[root@Nginx ~]# ssh-keygen -t rsa
Generating public/private rsa key pair.
Enter file in which to save the key (/root/.ssh/id_rsa):
Enter passphrase (empty for no passphrase):
Enter same passphrase again:
Your identification has been saved in /root/.ssh/id_rsa.
Your public key has been saved in /root/.ssh/id_rsa.pub.
The key fingerprint is:
0b:ca:be:1f:0f:b3:3a:aa:cc:c8:76:2c:76:25:59:fd root@Nginx
The key's randomart image is:
+--[ RSA 2048]----+
|                 |
|                 |
|      .          |
|     . .         |
|    o . S        |
|   + o . E       |
|  . = + .        |
|=+ =.  *         |
|===.+=o .        |
+-----------------+
2.将密钥传输至各节点
[root@Nginx ~]# ssh-copy-id -i .ssh/id_rsa.pub root@192.168.0.40
root@192.168.0.40's password:
Now try logging into the machine, with "ssh 'root@192.168.0.40'", and check in:
  .ssh/authorized_keys
to make sure we haven't added extra keys that you weren't expecting.
3.测试
[root@Nginx ~]# date; ssh 192.168.0.40 'date'
2017年 02月 10日 星期五 14:24:45 CST
2017年 02月 10日 星期五 14:24:46 CST
4.iptables与selinux规则放行或禁用
[root@Nginx ~]# getenforce
Disabled
[root@Nginx ~]# service iptables stop
5.各节点均进行上述操作
[root@node1 ~]# ssh-keygen -t rsa
[root@node1 ~]# ssh-copy-id -i .ssh/id_rsa.pub root@192.168.0.104
[root@node1 ~]# date; ssh 192.168.0.104 'date'
Fri Feb 10 14:27:02 CST 2017
Fri Feb 10 14:27:02 CST 2017　　

　　2、keepalived集群配置
　　1.各节点安装keepalived，yum安装（keepalived被官方收录到base源中）
[root@Nginx ~]# yum install keepalived -y
[root@node1 ~]# yum install keepalived -y　　

　　2.配置文件
　　Nginx配置
[root@Nginx ~]# cd /etc/keepalived/
[root@Nginx keepalived]# cp keepalived.conf{,.bak}
[root@Nginx keepalived]# grep -Ev '#|^$' keepalived.conf
! Configuration File for keepalived
global_defs {
   notification_email {
root@localhost           #收件人
   }
   notification_email_from kaadmin@localhost        #发件人
   smtp_server 127.0.0.1         #mail服务器
   smtp_connect_timeout 30      
   router_id Nginx                 
}
vrrp_instance VI_1 {
    state MASTER                 #vrrp工作模式master或backup
    interface eth0                                #vip配置接口
    virtual_router_id 51                          #同一虚拟路由id一致
    priority 100                 #优先级
    advert_int 1                 #发送心跳信息的时间
    authentication {
        auth_type PASS           #字符串认证
        auth_pass 51ea2a78
    }
    virtual_ipaddress {
        192.168.0.80/24 label eth0:0         #vip
    }
}　　

　　将配置文件复制到别的节点，并修改配置文件
[root@Nginx keepalived]# scp keepalived.conf node1:/etc/keepalived/
The authenticity of host 'node1 (192.168.0.40)' can't be established.
RSA key fingerprint is 46:dc:2d:3c:90:45:80:f4:21:40:03:2c:5b:ca:f0:77.
Are you sure you want to continue connecting (yes/no)? yes
Warning: Permanently added 'node1' (RSA) to the list of known hosts.
keepalived.conf                                   100% 3606     3.5KB/s   00:00　　

　　node1配置
[root@node1 keepalived]# cp keepalived.conf{,.bak}
[root@node1 keepalived]# egrep -v '#|^$' keepalived.conf
! Configuration File for keepalived
global_defs {
   notification_email {
root@localhost
   }
   notification_email_from kaadmin@localhost
   smtp_server 127.0.0.1
   smtp_connect_timeout 30
   router_id node1
}
vrrp_instance VI_1 {
    state BACKUP
    interface eth0
    virtual_router_id 51
    priority 90
    advert_int 1
    authentication {
        auth_type PASS
        auth_pass 51ea2a78
    }
    virtual_ipaddress {
        192.168.0.80/24 label eth0:0
    }
}　　

　　3.启动日志（各节点一同修改）
[root@Nginx keepalived]# vim /etc/sysconfig/keepalived
KEEPALIVED_OPTIONS="-D -S 3"
[root@Nginx keepalived]# vim /etc/rsyslog.conf
local7.*                                                /var/log/boot.log
local3.*                                                /var/log/keepalived.log
[root@Nginx keepalived]# service rsyslog restart　　

　　4.启动服务并测试
[root@Nginx keepalived]# service keepalived start; ssh node1 'service keepalived start'
[root@Nginx keepalived]# ifconfig eth0:0
eth0:0    Link encap:Ethernet  HWaddr 00:0C:29:8E:59:EC  
          inet addr:192.168.0.80  Bcast:0.0.0.0  Mask:255.255.255.0
          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
          Interrupt:19 Base address:0x2000
[root@Nginx keepalived]# ps -ef | grep keepalived
root      2532     1  0 19:49 ?        00:00:00 /usr/sbin/keepalived -D
root      2533  2532  0 19:49 ?        00:00:00 /usr/sbin/keepalived -D
root      2535  2532  0 19:49 ?        00:00:00 /usr/sbin/keepalived -D
root      2543  1996  0 19:53 pts/0    00:00:00 grep keepalived　　

　　三、手动调度
　　1、配置vrrp脚本并调用（各节点）
[root@Nginx keepalived]# !gre
grep -Ev '#|^$' keepalived.conf
! Configuration File for keepalived
global_defs {
   notification_email {
root@localhost
   }
   notification_email_from kaadmin@localhost
   smtp_server 127.0.0.1
   smtp_connect_timeout 30
   router_id Nginx
}
#vrrp脚本，检查该目录下是否有down文件，有则权重减2，无则不进行操作
vrrp_script chk_maintance {
    script "[[ -f /etc/keepalived/down ]] && exit 1 || exit 0"
    interval 1         
    weight -2
}
vrrp_instance VI_1 {
    state MASTER
    interface eth0
    virtual_router_id 51
    priority 100
    advert_int 1
    authentication {
        auth_type PASS
        auth_pass 51ea2a78
    }
    virtual_ipaddress {
        192.168.0.80/24 label eth0:0
    }
    #调用脚本
    track_script {
chk_maintance
    }
}　　2、测试
[root@Nginx keepalived]# touch /etc/keepalived/down
[root@Nginx keepalived]# ip add | grep eth0
2: eth0:  mtu 1500 qdisc pfifo_fast state UP qlen 1000
    inet 192.168.0.104/24 brd 192.168.0.255 scope global eth0
[root@node1 keepalived]# ip addr | grep eth0
2: eth0:  mtu 1500 qdisc pfifo_fast state UP qlen 1000
    inet 192.168.0.40/24 brd 192.168.0.255 scope global eth0
    inet 192.168.0.80/24 scope global secondary eth0:0
[root@Nginx keepalived]# rm down
rm：是否删除普通空文件 "down"？y   
[root@Nginx keepalived]# ip add | grep eth0
2: eth0:  mtu 1500 qdisc pfifo_fast state UP qlen 1000
    inet 192.168.0.104/24 brd 192.168.0.255 scope global eth0
    inet 192.168.0.80/24 scope global secondary eth0:0