Keepalived+LVS高可用负载均衡集群

概述

　　Keepalived是专门针对LVS设计的一款强大的辅助工具，主要用来提供故障切换(Failover)和健康检查(HeathChecking)功能——判断LVS负载调度器、节点服务器的可用性，及时隔离并替换为新的服务器，当故障主机恢复后将其重新加入群集。
Keepalived的官方网站位于http：//www.keepalived.org/
Keepalived的热备方式
　　Keepalived采用VRRP(Virtual Router Redundancy Protocol，虚拟路由冗余协议)热备份协议，以软件的方式实现Linux服务器的多机热备功能。VRRP是针对路由器的一种备份解决方案——由多台路由器组成一个热备组，通过共用的虚拟ip地址对外提供服务；每个热备组内同一时刻只有一台主路由器提供服务，其他路由器处于冗余状态，若当前在线的路由器失效，则其他路由器会自动接替(优先级决定接替顺序)虚拟IP地址，以继续提供服务。热备组内的路由器之间进行转移，所以也称为漂移IP地址。使用Keepalived时，漂移地址的实现不需要手动建立虚接口配置文件(如eth0:0)而是由Keepalived根据配置文件自动管理。

(一主多从之间的优先级不能相同，否则会产生''脑裂"或"裂脑")

Keepalived的安装与服务控制

1.安装支持软件

在编译安装Keepallved之前，必须先安装内核开发包kernel-devel，以及openss1一devel、popt-devel等支持库。除此之外，在LVS群集环境中应用时，也需要用到rpvsadm管理工具。

[root@Keepalived ~]# yum -y install kernel-devel openssl-devel popt-devel
[root@Keepalived ~]# yum -y install ipvsadm

2.编译安装keepalived

[root@Keepalived ~]# tar zxvf keepalived-1.2.13.tar.gz -C /usr/src/
[root@Keepalived ~]# cd /usr/src/keepalived-1.2.13/
[root@Keepalived keepalived-1.2.13]# ./configure --prefix=/ --with-kernel-dir=/usr/src/kernels/2.6.32-431.el6.x86_64/
[root@Keepalived keepalived-1.2.13]# make 
[root@Keepalived keepalived-1.2.13]# make install

只有使用LVS时才需要参数 --with-kernel-dir

3.使用Keepalived服务

[root@Keepalived ~]# ls -1 /etc/init.d/keepalived
-rwxr-xr-x 1 root root 1288 11月 8 16:23  /etc/init.d/keepalived
[root@Keepalived ~]# chkconfig --add keepalived
[root@Keepalived ~]# chkconfig keepalived on

配置文件：

　　Keepalived服务的配置目录位于/etc/Keepalived/。其中Keepalived.conf是主配置文件；另外包括一个子目录samples/,提供了许多配置样例参考。在Keepalived的配置文件中，使用“global_defs {...}"区段指定全局参数，使用“vrrp_instance 实例名称 {...}"区段指定VRRR热备参数，注释文字以“！”符号开头。
　　在同一个Keepalived热备组内，所有服务器的Keepalived配置文件基本相同，包括路由器名称，虚拟路由器的ID号，认证信息，漂移地址，心跳频率等。不同之处主要在于路由器名称热备状态，优先级。

• 路由器名称(router_id)：建议为每个参与热备的服务器指定不同的名称；
• 热备状态(state)：至少应有一台主服务器，将状态设为MASTER；可以有多台备用的服务器，将状态设为备用服务器；
• 优先级(priority)：数值越大则取得VIP控制权的优先级越高，因此主服务器的优先级应设为最高；其他备用服务器的优先级可依次递减，但不要相同，以免在争夺VIP控制权时发生冲突；

!全局配置
global_defs {
    router_id LVS_HA_R1    //主调度器的名称
}
!虚拟实例配置
vrrp_instance VI_1 {
    state MASTER           //主调度器的热备状态(MASTER/BACKUP)
    interface eth0       //承载VIP地址的物理接口
    virtual_router_id 51   //虚拟路由器的ID号，每个热备组保持一致
    priority 100           //主调度器的优先级
    advert_int 1       //通告间隔秒数(心跳频率)
    authentication {       //主、从热备认证信息(每个热备组保持一致)
        auth_type PASS       //认证类型
        auth_pass 1111       //密码子串
    }
    virtual_ipaddress {
        172.16.1.130       //指定集群VIP地址，可以有多个
    }
}

!Web服务器池配置
virtual_server 172.16.1.130 80 {               //虚拟服务器地址（VIP）、端口
    delay_loop 15                              //健康检查时间的间隔（秒）
    lb_algo rr                                 //调度算法(轮询（rr）)
    lb_kind DR                                 //群集工作模式，(DR/NAT)
    persistence 60                             //连接保持时间（秒
    protocol TCP                               //应用服务采用的是TCP协议
    real_server 172.16.1.131 80 {              //第一个Web节点的地址、端口
        weight 1                               //节点权重
        TCP_CHECK {                            //健康检查方式
                connect_port  80               //检查的目标端口
                connect_timeout  3             //连接超时（秒）
                nb_get_retry  3                //重试次数
                delay_before_retry  4          //重试间隔（秒）
            }
    }
    real_server 172.16.1.132 80 {              //第二个Web节点的地址、端口
        ......//省略部分信息
    }
     real_server 172.16.1.133 80 {             //第三个Web节点的地址、端口
        ......//省略部分信息
    }
     real_server 172.16.1.134 80 {             //第四个Web节点的地址、端口
        ......//省略部分信息
    }
}

Keepalived+LVS(NAT模式)

不需要配置LVS，因为keepalived去调用LVS内核模块

1.配置IP

略，Web服务器和Client客户端需要指定网关，都为VIP地址

2.配置Keepalived服务器(主-从)

 1)调整响应参数

[root@Keepalived ~]# vim /etc/sysctl.conf 
修改：
net.ipv4.ip_forward = 1
添加：
net.ipv4.conf.all.send_redirects = 0
net.ipv4.conf.default.send_redirects = 0
net.ipv4.conf.eth0.send_redirects = 0
[root@Keepalived ~]# sysctl -p

 2)安装Keepalived软件与ipvsadm管理工具

[root@Keepalived ~]# yum -y install ipvsadm
[root@Keepalived ~]# yum -y install kernel-devel openssl-devel popt-devel
[root@Keepalived ~]# tar zxvf keepalived-1.2.13.tar.gz -C /usr/src/
[root@Keepalived ~]# cd /usr/src/keepalived-1.2.13/
[root@Keepalived keepalived-1.2.13]# ./configure --prefix=/ --with-kernel-dir=/usr/src/kernels/2.6.32-431.el6.x86_64/
[root@Keepalived keepalived-1.2.13]# make 
[root@Keepalived keepalived-1.2.13]# make install
[root@Keepalived ~]# chkconfig --add keepalived
[root@Keepalived ~]# chkconfig keepalived on

 3)配置Keepalived

(1)全局配置、热备配置

[root@Keepalived ~]# cp /etc/keepalived/keepalived.conf /etc/keepalived/keepalived.conf.bak
[root@Keepalived ~]# vim  /etc/keepalived/keepalived.conf

global_defs {
   router_id LVS_MSATER_1        //主调度器的名称
}

vrrp_instance VI_1 {            //第一个实例的配置(VIP:1.1.1.1)
    state MASTER            //主调度器的热备状态
    interface eth0            //本网段提供服务的网卡设备名称
    virtual_router_id 51
    priority 100            //主调度器的优先级
    advert_int 1
    authentication {
        auth_type PASS
        auth_pass 1111
    }
    virtual_ipaddress {
        1.1.1.1                //VIP地址配置
    }
}

vrrp_instance VI_1 {            //第二个实例的配置(VIP:192.168.10.1)
    state MASTER
    interface eth1
    virtual_router_id 51
    priority 100
    advert_int 1
    authentication {
        auth_type PASS
        auth_pass 1111
    }
    virtual_ipaddress {
        192.168.10.1
    }
}

! Configuration File for keepalived

global_defs {
   router_id LVS_Savle_1        //修改
}

vrrp_instance VI_1 {
    state BACKUP            //修改
    interface eth0
    virtual_router_id 51
    priority 90                //修改
    advert_int 1
    authentication {
        auth_type PASS
        auth_pass 1111
    }
    virtual_ipaddress {
    1.1.1.1
    }
}

vrrp_instance VI_1 {
    state BACKUP            //修改
    interface eth2
    virtual_router_id 51
    priority 90                //修改
    advert_int 1
    authentication {
        auth_type PASS
        auth_pass 1111
    }
    virtual_ipaddress {
        192.168.10.1
    }
}

 (2)Web服务器池配置

virtual_server 1.1.1.1 80 {
    delay_loop 15
    lb_algo rr
    lb_kind NAT
    protocol TCP
    real_server 192.168.10.100 80 {
        weight 1
        TCP_CHECK {
            connect_port 80
            connect_timeout 3
            nb_get_retry 3
            delay_before_retry 4
        }
    }
    real_server 192.168.10.200 80 {
        weight 1
    TCP_CHECK {
        connect_port 80
            connect_timeout 3
        nb_get_retry 3
        delay_before_retry 4
       }
    }    
}

 使用ip工具可以查看漂移IP(主)

[root@Keepalived ~]# ip a
......
2: eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP qlen 1000
    link/ether 00:0c:29:85:d4:5c brd ff:ff:ff:ff:ff:ff
    inet 1.1.1.10/8 brd 1.255.255.255 scope global eth0
    inet 1.1.1.1/32 scope global eth0
    inet6 fe80::20c:29ff:fe85:d45c/64 scope link 
       valid_lft forever preferred_lft forever3: eth1: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP qlen 1000
    link/ether 00:0c:29:85:d4:70 brd ff:ff:ff:ff:ff:ff
    inet 192.168.10.10/24 brd 192.168.10.255 scope global eth2
    inet 192.168.10.1/32 scope global eth2
    inet6 fe80::20c:29ff:fe85:d470/64 scope link 
       valid_lft forever preferred_lft forever

5）配置Web节点服务器(各Web服务器配置相同)

安装httpd服务，创建测试页面，并启动httpd服务

[root@Web1 ~]#echo "LVS test 1" > /var/www/html/index.html            //第一个web服务器内容
[root@Web2 ~]#echo "LVS test 2" > /var/www/html/index.html            //第二个web服务器内容

 Keepalived+LVS(DR模式)

 1.配置IP地址

略

2.配置Keeplives服务器(主--从)

1)调整响应参数

[root@Keepalived ~]# vim /etc/sysctl.conf 
添加：
net.ipv4.conf.all.send_redirects = 0
net.ipv4.conf.default.send_redirects = 0
net.ipv4.conf.eth0.send_redirects = 0
[root@Keepalived ~]# sysctl -p

2)安装Keepalived软件与ipvsadm管理工具

[root@Keepalived ~]# yum -y install ipvsadm
[root@Keepalived ~]# yum -y install kernel-devel openssl-devel popt-devel
[root@Keepalived ~]# tar zxvf keepalived-1.2.13.tar.gz -C /usr/src/
[root@Keepalived ~]# cd /usr/src/keepalived-1.2.13/
[root@Keepalived keepalived-1.2.13]# ./configure --prefix=/ --with-kernel-dir=/usr/src/kernels/2.6.32-431.el6.x86_64/
[root@Keepalived keepalived-1.2.13]# make 
[root@Keepalived keepalived-1.2.13]# make install
[root@Keepalived ~]# chkconfig --add keepalived
[root@Keepalived ~]# chkconfig keepalived on

3)配置Keepalived

(1)全局配置、热备配置

[root@Keepalived ~]# cp /etc/keepalived/keepalived.conf /etc/keepalived/keepalived.conf.bak
[root@Keepalived ~]# vim  /etc/keepalived/keepalived.conf

global_defs {
   router_id LVS_MSATER_1        //主调度器的名称
}

vrrp_instance VI_1 {            //第一个实例的配置(VIP:1.1.1.1)
    state MASTER            //主调度器的热备状态
    interface eth0            //本网段提供服务的网卡设备名称
    virtual_router_id 51
    priority 100            //主调度器的优先级
    advert_int 1
    authentication {
        auth_type PASS
        auth_pass 1111
    }
    virtual_ipaddress {
        1.1.1.1                //VIP地址配置
    }
}

global_defs {
   router_id LVS_Savle_1        //主调度器的名称
}

vrrp_instance VI_1 {            //第一个实例的配置(VIP:1.1.1.1)
    state BACKUP            //主调度器的热备状态
    interface eth0            //本网段提供服务的网卡设备名称
    virtual_router_id 51
    priority 90            //主调度器的优先级
    advert_int 1
    authentication {
        auth_type PASS
        auth_pass 1111
    }
    virtual_ipaddress {
        1.1.1.1                //VIP地址配置
    }
}

 (2)Web服务器池配置

virtual_server 1.1.1.1 80 {
    delay_loop 15
    lb_algo rr
    lb_kind DR        //调整模式(DR)
    protocol TCP
    real_server 1.1.1.100 80 {        //Web主机的地址
        weight 1
        TCP_CHECK {
            connect_port 80
            connect_timeout 3
            nb_get_retry 3
            delay_before_retry 4
        }
    }
    real_server 1.1.1.200 80 {
        weight 1
    TCP_CHECK {
        connect_port 80
            connect_timeout 3
        nb_get_retry 3
        delay_before_retry 4
       }
    }    
}

[root@Keepalived ~]# ip a
1: lo: <LOOPBACK,UP,LOWER_UP> 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: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP qlen 1000
    link/ether 00:0c:29:85:d4:5c brd ff:ff:ff:ff:ff:ff
    inet 1.1.1.10/8 brd 1.255.255.255 scope global eth0
    inet 1.1.1.1/32 scope global eth0
    inet6 fe80::20c:29ff:fe85:d45c/64 scope link 
       valid_lft forever preferred_lft forever

3.配置Web节点服务器

1)设置VIP

[root@Web ~]# cd /etc/sysconfig/network-scripts/
[root@Web network-scripts]# cp ifcfg-lo ifcfg-lo:0
[root@Web network-scripts]# vim ifcfg-lo:0
修改为：
DEVICE=lo:0
IPADDR=1.1.1.1
NETMASK=255.255.255.255
ONBOOT=yes        
[root@Web network-scripts]# service network reload
[root@Web ~]# route add -host 1.1.1.1 dev lo:0        //添加路由
[root@Web ~]# echo "route add -host 1.1.1.1 dev lo:0" >> /etc/rc.local 

2）调整/proc参数(使用单播访问，提高相应速度)

[root@Web ]# vim /etc/sysctl.conf
添加:
net.ipv4.conf.all.arp_ignore = 1
net.ipv4.conf.all.arp_announce = 2
net.ipv4.conf.default.arp_ignore = 1
net.ipv4.conf.default.arp_announce = 2
net.ipv4.conf.lo.arp_ignore = 1
net.ipv4.conf.lo.arp_announce = 2
[root@localhost ]# sysctl -p

3）配置Web节点服务器(各Web服务器配置相同)

安装httpd服务，创建测试页面，并启动httpd服务

[root@Web1 ~]#echo "LVS test 1" > /var/www/html/index.html            //第一个web服务器内容
[root@Web2 ~]#echo "LVS test 2" > /var/www/html/index.html            //第二个web服务器内容