Linux架构之LVS-DR和keepalived配置
LVS是linux virtual server的简写linux虚拟服务器，是一个虚拟的服务器集群系统，可以再unix/linux平台下实现负载均衡集群功能。 DR模式（直接路由模式）Virtual server via direct routing (vs/dr)
DR模式是通过改写请求报文的目标MAC地址，将请求发给真实服务器的，而真实服务器响应后的处理结果直接返回给客户端用户。同TUN模式一样，DR模式可以极大的提高集群系统的伸缩性。而且DR模式没有IP隧道的开销，对集群中的真实服务器也没有必要必须支持IP隧道协议的要求。但是要求调度器LB与真实服务器RS都有一块网卡连接到同一物理网段上，必须在同一个局域网环境。
DR模式是互联网使用比较多的一种模式。
DR模式原理图：
LVS调度算法的生产环境选型：1、一般的网络服务，如http，mail，mysql等常用的LVS调度算法为：a.基本轮询调度rrb.加权最小连接调度wlcc.加权轮询调度wrcDR配置
Director serverchumjtest01
eth0 172.31.24.199 VIP:172.31.24.197
Realserver01chumjtest02eth0 172.31.24.200VIP lo:0:172.31.24.197
Realserver02chumjtest03eth0 172.31.24.198VIP lo:0:172.31.24.197
实验准备
1.关闭防火墙 iptables -F;
2.关闭selinux： setenforce 0
3.在Director Server安装好lvs4.realserver都需要安装nginx
Dirserver配置
首先为了执行方便编写一个脚本
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#!/bin/bash
echo 1 > /proc/sys/net/ipv4/ip_forward //开启转发功能
ipv=/sbin/ipvsadm
vip=172.31.24.197 //VIP的IP地址
rs1=172.31.24.200 //RS1的IP地址
rs2=172.31.24.198 //RS2的IP地址
ifconfig eth0:0 $vip broadcast $vip netmask 255.255.255.255 up
route add -host $vip dev eth0:0
$ipv -C
$ipv -A -t $vip:80 -s rr //轮询,意思是一次转发，
$ipv -a -t $vip:80 -r $rs1:80 -g -w 1 //g表示LVS-DR模式 w表示权重
$ipv -a -t $vip:80 -r $rs2:80 -g -w 1
Realserver 配置
同样建立一个脚本，分别在放在两台RS上面。
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#!/bin/bash
vip=172.31.24.197
ifconfig lo:0 $vip broadcast $vip netmask 255.255.255.255 up
route add -host $vip 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
然后director上执行: bash /usr/local/sbin/lvs_dr.sh
两台rs上执行: bash /usr/local/sbin/lvs_dr_rs.sh
测试
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# curl 172.31.24.197
Chumjtest03
注：
主要realserver 权重不一样要修改dirserver配置文件
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#!/bin/bash
echo 1 > /proc/sys/net/ipv4/ip_forward //开启转发功能
ipv=/sbin/ipvsadm
vip=172.31.24.197 //VIP的IP地址
rs1=172.31.24.200 //RS1的IP地址
rs2=172.31.24.198 //RS2的IP地址
ifconfig eth0:0 $vip broadcast $vip netmask 255.255.255.255 up
route add -host $vip dev eth0:0
$ipv -C
$ipv -A -t $vip:80 -s wrr //加权轮询,依照优先级转发
$ipv -a -t $vip:80 -r $rs1:80 -g -w 3 //w表示权重，修改权重
$ipv -a -t $vip:80 -r $rs2:80 -g -w 1
Keepalived安装
如果由之前的配置要清理下
ipvsadm -C
ifconfig eth0:0 down
由于环境限制这里将RS02当做keepalived备机，在真是环境中不建议这么做。最好另外有一台设备当做备机
进入keepalived，对配置文件进行配置
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# cat /etc/keepalived/keepalived.conf
vrrp_instance VI_1 {
state MASTER #备用服务器上为 BACKUP
interface eth0
virtual_router_id 51
priority 100#备用服务器上为90
advert_int 1
authentication {
auth_type PASS
auth_pass 1111
}
virtual_ipaddress {
192.168.31.110
}
}
virtual_server 192.168.31.110 80 {
delay_loop 6 #(每隔10秒查询realserver状态)
lb_algo wlc #(lvs 算法)
lb_kind DR #(Direct Route)
persistence_timeout 60 #(同一IP的连接60秒内被分配到同一台realserver)
protocol TCP #(用TCP协议检查realserver状态)
real_server 192.168.31.100 80 {
weight 100 #(权重)
TCP_CHECK {
connect_timeout 10 #(10秒无响应超时)
nb_get_retry 3
delay_before_retry 3
connect_port 80
}
}
real_server 192.168.31.101 80 {
weight 100
TCP_CHECK {
connect_timeout 10
nb_get_retry 3
delay_before_retry 3
connect_port 80
}
}
}
将主机的keepalived配置文件拷贝到备机上
只需要修改stateMASTER-> state BACKUPpriority 100 ->priority 90
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# scp keepalived.conf root@172.31.24.200:/etc/keepalived
进入chumjtest02
# vim keepalived.conf
vrrp_instance VI_1 {
state BACKUP #备用服务器上为 BACKUP
interface eth0
virtual_router_id 51
priority 90#备用服务器上为90
advert_int 1
authentication {
auth_type PASS
auth_pass 1111
}
virtual_ipaddress {
172.31.24.197
}
}
virtual_server 172.31.24.197 80 {
delay_loop 6 #(每隔10秒查询realserver状态)
lb_algo wlc #(lvs 算法)
lb_kind DR #(Direct Route)
persistence_timeout 60 #(同一IP的连接60秒内被分配到同一台realserver)
protocol TCP #(用TCP协议检查realserver状态)
real_server 172.31.24.200 80 {
weight 100 #(权重)
TCP_CHECK {
connect_timeout 10 #(10秒无响应超时)
nb_get_retry 3
delay_before_retry 3
connect_port 80
}
}
real_server 172.31.24.198 80 {
weight 100
TCP_CHECK {
connect_timeout 10
nb_get_retry 3
delay_before_retry 3
connect_port 80
}
}
}
注：
1.配置完keepalived后需要开启端口转发（主从都需要）
2.RS上都需要执行lvs_dr_rs.sh脚本
3.两个director上启动keepalived服务（先主后从）
启动keepalived服务会自动生成vip和ipvsadm规则，不需要再去执行上面提到的/usr/local/sbin/lvs_dr.sh 脚本。
启动keepalived
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# service keepalived restart
Stopping keepalived:
Starting keepalived:
# ipvsadm -ln
IP Virtual Server version 1.2.1 (size=4096)
Prot LocalAddress:Port Scheduler Flags
-> RemoteAddress:Port Forward Weight ActiveConn InActConn
TCP172.31.24.197:80 wlc persistent 60
-> 172.31.24.198:80 Route 100 0 0
-> 172.31.24.200:80 Route 100 0 0
# ip addr
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 mq state UP qlen 1000
link/ether 00:50:56:b3:79:e3 brd ff:ff:ff:ff:ff:ff
inet 172.31.24.199/24 brd 172.31.24.255 scope global eth0
inet 172.31.24.197/32 scope global eth0 //VIP已经启动
inet6 fe80::250:56ff:feb3:79e3/64 scope link
valid_lft forever preferred_lft forever
测试
可以将keepalived的master服务停止，看下在备机上是否启动。
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# service keepalived stop
Stopping keepalived:
#
从备机的日志上看到VIP已经在备机上启动
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# tail -f /var/log/messages
Jan 11 17:21:00 chumjtest02 Keepalived_vrrp: VRRP_Instance(VI_1) Transition to MASTER STATE
Jan 11 17:21:01 chumjtest02 Keepalived_vrrp: VRRP_Instance(VI_1) Entering MASTER STATE
Jan 11 17:21:01 chumjtest02 Keepalived_vrrp: VRRP_Instance(VI_1) setting protocol VIPs.
Jan 11 17:21:01 chumjtest02 Keepalived_vrrp: VRRP_Instance(VI_1) Sending gratuitous ARPs on eth0 for 172.31.24.197
Jan 11 17:21:01 chumjtest02 Keepalived_healthcheckers: Netlink reflector reports IP 172.31.24.197 added
Jan 11 17:21:06 chumjtest02 Keepalived_vrrp: VRRP_Instance(VI_1) Sending gratuitous ARPs on eth0 for 172.31.24.197
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# ip addr
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
inet 172.31.24.197/32 brd 172.31.24.197 scope global lo:0
inet6 ::1/128 scope host
valid_lft forever preferred_lft forever
2: eth1: <BROADCAST,MULTICAST> mtu 1500 qdisc noop state DOWN qlen 1000
link/ether 00:50:56:b3:0e:c3 brd ff:ff:ff:ff:ff:ff
3: eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP qlen 1000
link/ether 00:50:56:b3:68:a0 brd ff:ff:ff:ff:ff:ff
inet 172.31.24.200/24 brd 172.31.24.255 scope global eth0
inet 172.31.24.197/32 scope global eth0 //VIP已经在备机上启动
inet6 fe80::250:56ff:feb3:68a0/64 scope link
valid_lft forever preferred_lft forever
注：
keepalived的日志在/var/log/messages，可以通过检查日志来发现问题。
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