实战 LVS+Keepalived 实现负载均衡和高可用
1.软件介绍LVS是Linux Virtual Server的简写，意即Linux虚拟服务器，是一个虚拟的服务器集群系统，可以实现LINUX平台下的简单负载均衡。
LVS负载均衡有4种负载均衡方式
a.DR 模式
b.NAT 模式
c.Tunnel 模式
d.Full NAT 模式
LVS负载均衡8种调度算法
（rr,wrr,lc,wlc,lblc,lblcr,dh,sh）
各个模式的原理在此不再赘述，本文使用DR模式，rr调度算法。
Keepalived 是运行在lvs 之上，它的主要功能是实现真实机的故障隔离及负载均衡器间的失败切换，提高系统的可用性。
2.实战安装
环境配置
# cat /etc/redhat-release
CentOS release 6.8 (Final)
# uname -r
2.6.32-642.6.1.el6.x86_64
软件
ipvsadm-1.26.tar.gzkeepalived-1.1.19.tar.gz
信息列表
服务器名称 IP
LVS 做主(LVS-master)10.89.3.103 Keepalived 做备(LVS-backup)10.89.3.102 lamp 做web1(real_server)10.89.3.100 lnmp 做web2(real_server)10.89.3.101 #LVS vip设置在keepalived的配置文件里 10.89.3.168
LVS+keepalived的安装和配置-2台电脑（LVS,Keepalived）都要安装。
安装lvs软件
ln -s /usr/src/kernels/2.6.32-642.6.1.el6.x86_64/ /usr/src/linux
yum install libnl* popt* -y
tar zxf ipvsadm-1.26.tar.gz
cd ipvsadm-1.26
make
make install
# modprobe ip_vs#把ip_vs模块加入内核
# lsmod|grep ip_vs#查看是否安装
ip_vs 1268970
libcrc32c 12461 ip_vs
ipv6 336282265 ip_vs
#出现上面的结果，表示安装OK
安装keepalived软件
ln -s /usr/src/kernels/2.6.32-642.6.1.el6.x86_64 /usr/src/linux
yum install openssl openssl-devel -y
tar xf keepalived-1.1.19.tar.gz
cd keepalived-1.1.19
./configure
make
make install
配置keepalived规范启动
/bin/cp /usr/local/etc/rc.d/init.d/keepalived /etc/init.d/
/bin/cp /usr/local/etc/sysconfig/keepalived /etc/sysconfig/
mkdir /etc/keepalived -p
/bin/cp /usr/local/etc/keepalived/keepalived.conf /etc/keepalived/
/bin/cp /usr/local/sbin/keepalived /usr/sbin/
/etc/init.d/keepalived start
ps -ef|grep keep
root 6342 10 17:42 ? 00:00:00 keepalived -D
root 6344 63420 17:42 ? 00:00:00 keepalived -D
root 6345 63420 17:42 ? 00:00:00 keepalived -D
root 6347 34900 17:42 pts/0 00:00:00 grep keep
#出现 3个keepalived -D，表示安装OK
3. 配置keepadlived
LVS-Master的配置文件如下：
# cat /etc/keepalived/keepalived.conf
! Configuration File for keepalived
global_defs {
notification_email {
114653379@qq.com
}
notification_email_from 114653379@qq.com
smtp_server 127.0.0.1
smtp_connect_timeout 30
router_id LVS_7
}
vrrp_instance VI_1 {
state MASTER
interface eth0
virtual_router_id 55
priority 150
advert_int 1
authentication {
auth_type PASS
auth_pass 1111
}
virtual_ipaddress {
10.89.3.168/24
}
}
virtual_server 10.89.3.168 80 {
delay_loop 6
lb_algo wrr
lb_kind DR
nat_mask 255.255.255.0
persistence_timeout 300
protocol TCP
real_server 10.89.3.100 80 {
weight 1
TCP_CHECK {
connect_timeout 8
nb_get_retry 3
delay_before_retry 3
connect_port 80
}
}
real_server 10.89.3.101 80 {
weight 1
TCP_CHECK {
connect_timeout 8
nb_get_retry 3
delay_before_retry 3
connect_port 80
}
}
}
LVS-backup的配置文件如下：
# cat /etc/keepalived/keepalived.conf
! Configuration File for keepalived
global_defs {
notification_email {
114653379@qq.com
}
notification_email_from 114653379@qq.com
smtp_server 127.0.0.1
smtp_connect_timeout 30
router_id LVS_2
}
vrrp_instance VI_1 {
state BACKUP
interface eth0
virtual_router_id 55
priority 100
advert_int 1
authentication {
auth_type PASS
auth_pass 1111
}
virtual_ipaddress {
10.89.3.168/24
}
}
virtual_server 10.89.3.168 80 {
delay_loop 6
lb_algo wrr
lb_kind DR
nat_mask 255.255.255.0
persistence_timeout 300
protocol TCP
real_server 10.89.3.100 80 {
weight 1
TCP_CHECK {
connect_timeout 8
nb_get_retry 3
delay_before_retry 3
connect_port 80
}
}
real_server 10.89.3.101 80 {
weight 1
TCP_CHECK {
connect_timeout 8
nb_get_retry 3
delay_before_retry 3
connect_port 80
}
}
}
real_server的配置,2台客户端的脚本都一样！
# cat /server/scripts/ipvs_client.sh
#!/bin/bash
# description: Config realserver lo and apply noarp
SNS_VIP=10.89.3.168
. /etc/rc.d/init.d/functions
case "$1" in
start)
/sbin/ifconfig lo:0 $SNS_VIP netmask 255.255.255.255 broadcast $SNS_VIP
/sbin/route add -host $SNS_VIP dev lo:0
echo "1" >/proc/sys/net/ipv4/conf/lo/arp_ignore
echo "2" >/proc/sys/net/ipv4/conf/lo/arp_announce
echo "1" >/proc/sys/net/ipv4/conf/all/arp_ignore
echo "2" >/proc/sys/net/ipv4/conf/all/arp_announce
sysctl -p >/dev/null 2>&1
echo "RealServer Start OK"
;;
stop)
ifconfig lo:0 down
route del $SNS_VIP >/dev/null 2>&1
echo "0" >/proc/sys/net/ipv4/conf/lo/arp_ignore
echo "0" >/proc/sys/net/ipv4/conf/lo/arp_announce
echo "0" >/proc/sys/net/ipv4/conf/all/arp_ignore
echo "0" >/proc/sys/net/ipv4/conf/all/arp_announce
echo "RealServer Stoped"
;;
*)
echo "Usage: $0 {start|stop}"
exit 1
esac
exit 0
----------------------------------------------
4.实战测试
4.1 测试VIP漂移
#使用命令 ip add 查看VIP
# /etc/init.d/keepalived start
Starting keepalived:
# ip add
1: lo:mtu 65536 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:29:4e:ca:a4 brd ff:ff:ff:ff:ff:ff
inet 10.89.3.102/24 brd 10.89.3.255 scope global eth0
inet 10.89.3.168/24 scope global secondary eth0
inet6 fe80::20c:29ff:fe4e:caa4/64 scope link
valid_lft forever preferred_lft forever
----------------------------------------------------------------
# ip add
1: lo:mtu 65536 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:29:3f:7c:0b brd ff:ff:ff:ff:ff:ff
inet 10.89.3.103/24 brd 10.89.3.255 scope global eth0
inet6 fe80::20c:29ff:fe3f:7c0b/64 scope link
valid_lft forever preferred_lft forever
------------------------------------------------------------------
#观察发现，此时VIP 在Lvs这台服务器上，现在把这台服务器Keepalived 服务停止
# /etc/init.d/keepalived stop
Stopping keepalived:
# ip add
1: lo:mtu 65536 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:29:4e:ca:a4 brd ff:ff:ff:ff:ff:ff
inet 10.89.3.102/24 brd 10.89.3.255 scope global eth0
inet6 fe80::20c:29ff:fe4e:caa4/64 scope link
valid_lft forever preferred_lft forever
#发现VIP已经漂移到另外一台上了，我们去看看
# ip add
1: lo:mtu 65536 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:29:3f:7c:0b brd ff:ff:ff:ff:ff:ff
inet 10.89.3.103/24 brd 10.89.3.255 scope global eth0
inet 10.89.3.168/24 scope global secondary eth0
inet6 fe80::20c:29ff:fe3f:7c0b/64 scope link
valid_lft forever preferred_lft forever
---------------------------------------------------------------------
4.2 测试web 服务
http://s3.运维网.com/wyfs02/M00/89/6E/wKiom1gS0YvAMom1AAAZUgsZVIk571.jpg-wh_500x0-wm_3-wmp_4-s_416387194.jpg
http://s3.运维网.com/wyfs02/M00/89/6C/wKioL1gS0YuhBFG1AAArvSELKE0158.jpg-wh_500x0-wm_3-wmp_4-s_2050596028.jpg
4.3查看连接情况
# ipvsadm -Lnc
IPVS connection entries
pro expire state source virtual destination
TCP 01:01FIN_WAIT 10.89.1.158:6289910.89.3.168:80 10.89.3.101:80
TCP 00:56FIN_WAIT 10.89.3.1:58996 10.89.3.168:80 10.89.3.100:80
TCP 00:56FIN_WAIT 10.89.3.1:58997 10.89.3.168:80 10.89.3.100:80
TCP 02:06NONE 10.89.3.1:0 10.89.3.168:80 10.89.3.100:80
TCP 03:44NONE 10.89.1.158:0 10.89.3.168:80 10.89.3.101:80
TCP 01:51FIN_WAIT 10.89.1.158:6260310.89.3.168:80 10.89.3.101:80
总结：LVS+Keepalived 可以实现负载均衡和高可用，到此我们验证配置结束！
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