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..tar.gz -C /usr/src/
[root@Keepalived ~]# cd /usr/src/keepalived-1.2./
[root@Keepalived keepalived-1.2.13]# ./configure --prefix=/ --with-kernel-dir=/usr/src/kernels/2.6.-.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 - /etc/init.d/keepalived
-rwxr-xr-x root root 11月 : /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 //虚拟路由器的ID号，每个热备组保持一致
priority //主调度器的优先级
advert_int //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 //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 { //虚拟服务器地址（VIP）、端口
delay_loop //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 //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 { //第一个Web节点的地址、端口
weight //节点权重
TCP_CHECK { //健康检查方式
connect_port //检查的目标端口
connect_timeout //连接超时（秒）
nb_get_retry //重试次数
delay_before_retry //重试间隔（秒）
}
}
real_server 172.16.1.132 { //第二个Web节点的地址、端口
......//省略部分信息
}
real_server 172.16.1.133 { //第三个Web节点的地址、端口
......//省略部分信息
}
real_server 172.16.1.134 { //第四个Web节点的地址、端口
......//省略部分信息
}
}
keepalived.conf
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 =
添加：
net.ipv4.conf.all.send_redirects =
net.ipv4.conf.default.send_redirects =
net.ipv4.conf.eth0.send_redirects =
[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..tar.gz -C /usr/src/
[root@Keepalived ~]# cd /usr/src/keepalived-1.2./
[root@Keepalived keepalived-1.2.]# ./configure --prefix=/ --with-kernel-dir=/usr/src/kernels/2.6.-.el6.x86_64/
[root@Keepalived keepalived-1.2.]# make
[root@Keepalived keepalived-1.2.]# 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
priority //主调度器的优先级
advert_int
authentication {
auth_type PASS
auth_pass
}
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
priority
advert_int
authentication {
auth_type PASS
auth_pass
}
virtual_ipaddress {
192.168.10.1
}
}
Master
! 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
priority //修改
advert_int
authentication {
auth_type PASS
auth_pass
}
virtual_ipaddress {
1.1.1.1
}
}
vrrp_instance VI_1 {
state BACKUP //修改
interface eth2
virtual_router_id
priority //修改
advert_int
authentication {
auth_type PASS
auth_pass
}
virtual_ipaddress {
192.168.10.1
}
}
Savle
(2)Web服务器池配置
virtual_server 1.1.1.1 {
delay_loop
lb_algo rr
lb_kind NAT
protocol TCP
real_server 192.168.10.100 {
weight
TCP_CHECK {
connect_port
connect_timeout
nb_get_retry
delay_before_retry
}
}
real_server 192.168.10.200 {
weight
TCP_CHECK {
connect_port
connect_timeout
nb_get_retry
delay_before_retry
}
}
}
Master--Savle
使用ip工具可以查看漂移IP(主)
[root@Keepalived ~]# ip a
......
: eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu qdisc pfifo_fast state UP qlen
link/ether :0c:::d4:5c brd ff:ff:ff:ff:ff:ff
inet 1.1.1.10/ brd 1.255.255.255 scope global eth0
inet 1.1.1.1/ scope global eth0
inet6 fe80::20c:29ff:fe85:d45c/ scope link
valid_lft forever preferred_lft forever: eth1: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu qdisc pfifo_fast state UP qlen
link/ether :0c:::d4: brd ff:ff:ff:ff:ff:ff
inet 192.168.10.10/ brd 192.168.10.255 scope global eth2
inet 192.168.10.1/ scope global eth2
inet6 fe80::20c:29ff:fe85:d470/ 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 =
net.ipv4.conf.default.send_redirects =
net.ipv4.conf.eth0.send_redirects =
[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
priority //主调度器的优先级
advert_int
authentication {
auth_type PASS
auth_pass
}
virtual_ipaddress {
1.1.1.1 //VIP地址配置
}
}
Master
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
priority //主调度器的优先级
advert_int
authentication {
auth_type PASS
auth_pass
}
virtual_ipaddress {
1.1.1.1 //VIP地址配置
}
}
Savle
(2)Web服务器池配置
virtual_server 1.1.1.1 {
delay_loop
lb_algo rr
lb_kind DR //调整模式(DR)
protocol TCP
real_server 1.1.1.100 { //Web主机的地址
weight
TCP_CHECK {
connect_port
connect_timeout
nb_get_retry
delay_before_retry
}
}
real_server 1.1.1.200 {
weight
TCP_CHECK {
connect_port
connect_timeout
nb_get_retry
delay_before_retry
}
}
}
Master-Savel
[root@Keepalived ~]# ip a
: lo: <LOOPBACK,UP,LOWER_UP> mtu qdisc noqueue state UNKNOWN
link/loopback ::::: brd :::::
inet 127.0.0.1/ scope host lo
inet6 ::/ scope host
valid_lft forever preferred_lft forever
: eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu qdisc pfifo_fast state UP qlen
link/ether :0c:::d4:5c brd ff:ff:ff:ff:ff:ff
inet 1.1.1.10/ brd 1.255.255.255 scope global eth0
inet 1.1.1.1/ scope global eth0
inet6 fe80::20c:29ff:fe85:d45c/ 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:
[root@Web network-scripts]# vim ifcfg-lo:
修改为：
DEVICE=lo:
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: //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 =
net.ipv4.conf.all.arp_announce =
net.ipv4.conf.default.arp_ignore =
net.ipv4.conf.default.arp_announce =
net.ipv4.conf.lo.arp_ignore =
net.ipv4.conf.lo.arp_announce =
[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