LVS（DR） + Keepalived 实现负载均衡
LVS（DR） + Keepalived 实现负载均衡高可用一、为什么要使 用负载均衡技术？
1、系统高可用性
2、系统可扩展性
3、负载均衡能力
LVS+keepalived能很好的实现以上的要求，LVS提 供负载均衡，keepalived提供健康检查，故障转移，提高系统的可用性！采用这样的架构以后 很容易对现有系统进行扩展，只要在后端添加或者减少realserver，只要更改lvs的 配置文件，并能实现无缝配置变更！
二、LVS+Keepalived介绍
1、LVS
LVS是一个开源的软件，可以实现LINUX平台下的简单负载均衡。LVS是Linux Virtual Server的缩写，意思是Linux虚拟服务器。目前有三种IP负 载均衡技术（VS/NAT、VS/TUN和VS/DR）；八种调度算法（rr,wrr,lc,wlc,lblc,lblcr,dh,sh）。
2、keepalived
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。
一、环境说明
本次试验使用的是2台前端代理服务器(LVS) 加上 keepalived，后端为了方便，使用apache来发布网页，达到测试的目的。
操作系统：centos7 64位
软件源：阿里云
2台服务器（LVS1、LVS2）安装 keepalived 和安装LVS 来反向代理
2台服务器（web1、web2）安装 apache 来提供服务
服务器的防火墙和selinux全部关闭
LVS1IP：192.168.163.158
LVS2IP：192.168.163.161
web1IP：192.168.163.159
web2IP：192.168.163.160
虚拟IP： 192.168.163.200
拓扑图如下：
https://s2.运维网.com/oss/201710/22/00c3f499d2e435fd1951a8b34660603e.jpg-wh_500x0-wm_3-wmp_4-s_807525350.jpg
二、环境安装
首先配置web服务器
1、首先为后端的2台web服务器安装apache
# yum install -y httpd
# yum install -y httpd
2、创建各自的网页
# echo "web1：192.168.163.159" > /var/www/html/index.html
# echo "web2：192.168.163.160" > /var/www/html/index.html
3、启动服务
# systemctl start httpd
# systemctl start httpd
4、编写脚本，为web服务器设置虚拟IP以及设置抑制ARP包
# vim /root/VIP.sh
#!/bin/bash
VIP=192.168.163.200 #这个为你要设置的VIP
case $1 in
start)
ifconfig lo:0 $VIP netmask 255.255.255.255 broadcast $VIP
/sbin/route add -host $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 $IP >/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 添加执行权限并执行该脚本
# chmod a+x VIP.sh
# bash /root/VIP.sh start
在web2上也执行该操作
在LVS服务器安装 LVS 和 Keepalived
1、安装软件包
# yum install -y ipvsadm keepalived
# yum install -y ipvsadm keepalived
2、编辑 LVS1的 keepalived 配置文件
# vim /etc/keepalived/keepalived.conf
! Configuration File for keepalived
global_defs {
notification_email {
root@localhost
}
notification_email_from keepalived@localhost
smtp_server 127.0.0.1
smtp_connect_timeout 30
router_id LVS
vrrp_mcast_group4 224.0.100.19
}
vrrp_instance VI_1 {
state BACKUP
interface ens32
virtual_router_id 51
priority 100
nopreempt
advert_int 1
authentication {
auth_type PASS
auth_pass xhk
}
virtual_ipaddress {
192.168.163.200 dev ens32
}
}
virtual_server 192.168.163.200 80 { # 定义转移ip端口80的集群服务
delay_loop 3
lb_algo rr
lb_kind DR
protocol TCP
sorry_server 127.0.0.1 80
real_server 192.168.163.159 80 { # 定义集群服务包含的RS 1
weight 1 # 权重为1
HTTP_GET { # 定义RS1的健康状态检测
url {
path /
status_code 200
}
connect_timeout 1
nb_get_retry 3
delay_before_retry 1
}
}
real_server 192.168.163.160 80 { # 定义集群服务包含的RS 2
weight 1 # 权重为1
HTTP_GET { # 定义RS2的健康状态检测
url {
path /
status_code 200
}
connect_timeout 1
nb_get_retry 3
delay_before_retry 1
}
}
}
3、编辑 LVS2的 keepalived 配置文件
# vim /etc/keepalived/keepalived.conf
! Configuration File for keepalived
global_defs {
notification_email {
root@localhost
}
notification_email_from keepalived@localhost
smtp_server 127.0.0.1
smtp_connect_timeout 30
router_id LVS
vrrp_mcast_group4 224.0.100.19
}
vrrp_instance VI_1 {
state BACKUP
interface ens32
virtual_router_id 51
priority 99
nopreempt
advert_int 1
authentication {
auth_type PASS
auth_pass xhk
}
virtual_ipaddress {
192.168.163.200 dev ens32
}
}
virtual_server 192.168.163.200 80 { # 定义转移ip端口80的集群服务
delay_loop 3
lb_algo rr
lb_kind DR
protocol TCP
sorry_server 127.0.0.1 80
real_server 192.168.163.159 80 { # 定义集群服务包含的RS 1
weight 1 # 权重为1
HTTP_GET { # 定义RS1的健康状态检测
url {
path /
status_code 200
}
connect_timeout 1
nb_get_retry 3
delay_before_retry 1
}
}
real_server 192.168.163.160 80 { # 定义集群服务包含的RS 2
weight 1 # 权重为1
HTTP_GET { # 定义RS2的健康状态检测
url {
path /
status_code 200
}
connect_timeout 1
nb_get_retry 3
delay_before_retry 1
}
}
} 2个配置文件不同的只是优先级的不同，分出MASTER，并且设置了不抢占模式，为的是防止业务切换国语频繁！
4、开启路由转发
# echo "1" /proc/sys/net/ipv4/ip_forward
# echo "1" /proc/sys/net/ipv4/ip_forward
5、设置虚拟IP
# ifconfig lo:0 192.168.163.200 broadcast 192.168.163.200 netmask 255.255.255.255 up
# ifconfig lo:0 192.168.163.200 broadcast 192.168.163.200 netmask 255.255.255.255 up
6、启动keepalived服务
# systemctl restart keepalived
# systemctl restart keepalived
三、测试环节
1、查看keepalived状态
# systemctl status keepalived
● keepalived.service - LVS and VRRP High Availability Monitor
Loaded: loaded (/usr/lib/systemd/system/keepalived.service; disabled; vendor preset: disabled)
Active: active (running) since Sun 2017-10-22 01:26:32 EDT; 3min 48s ago
Process: 2656 ExecStart=/usr/sbin/keepalived $KEEPALIVED_OPTIONS (code=exited, status=0/SUCCESS)
Main PID: 2657 (keepalived)
CGroup: /system.slice/keepalived.service
├─2657 /usr/sbin/keepalived -D
├─2658 /usr/sbin/keepalived -D
└─2659 /usr/sbin/keepalived -D
Oct 22 01:26:37 LVS1 Keepalived_vrrp: Sending gratuitous ARP on ens32 for 192.168.163.200
查看虚拟IP
# ip addr sh
1: lo:mtu 65536 qdisc noqueue state UNKNOWN qlen 1
link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
inet 127.0.0.1/8 scope host lo
valid_lft forever preferred_lft forever
inet 192.168.163.200/32 brd 192.168.163.200 scope global lo:0
valid_lft forever preferred_lft forever
inet6 ::1/128 scope host
valid_lft forever preferred_lft forever
2: ens32:mtu 1500 qdisc pfifo_fast state UP qlen 1000
link/ether 00:0c:29:5f:46:a6 brd ff:ff:ff:ff:ff:ff
inet 192.168.163.158/24 brd 192.168.163.255 scope global dynamic ens32
valid_lft 1654sec preferred_lft 1654sec
inet 192.168.163.200/32 scope global ens32
valid_lft forever preferred_lft forever
inet6 fe80::20c:29ff:fe5f:46a6/64 scope link
valid_lft forever preferred_lft forever
访问网页
# curl 192.168.163.200
web1：192.168.163.159
# curl 192.168.163.200
web2：192.168.163.160
将LVS1的Keepalived停掉
# systemctl stop keepalived
可以看到LVS拿到了VIP
# systemctl status keepalived
● keepalived.service - LVS and VRRP High Availability Monitor
Loaded: loaded (/usr/lib/systemd/system/keepalived.service; disabled; vendor preset: disabled)
Active: active (running) since Sun 2017-10-22 01:26:38 EDT; 6min ago
Process: 2553 ExecStart=/usr/sbin/keepalived $KEEPALIVED_OPTIONS (code=exited, status=0/SUCCESS)
Main PID: 2555 (keepalived)
CGroup: /system.slice/keepalived.service
├─2555 /usr/sbin/keepalived -D
├─2556 /usr/sbin/keepalived -D
└─2557 /usr/sbin/keepalived -D
Oct 22 01:32:50 LVS2 Keepalived_vrrp: Sending gratuitous ARP on ens32 for 192.168.163.200
继续访问网页
# curl 192.168.163.200
web1：192.168.163.159
# curl 192.168.163.200
web2：192.168.163.160
测试成功！！！！！！！！！！！！！！！！！！！
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