LVS负载均衡群集再相遇之DR模式+Keepalived
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一、LVS-DR集群概述
LVS-DR(Linux Virtual Server Director Server)工作模式,是生产环境中最常用的一 种工作模式。
1.1、DR模式工作原理
LVS-DR 模式,Director Server 作为群集的访问入口,不作为网关使用,节点 Director Server 与 Real Server 需要在同一个网络中,返回给客户端的数据不需要经过 Director Server。为了响应对整个群集的访问,Director Server 与 Real Server 都需要配置 VIP 地址
1.2、LVS-DR数据包流量分析(同一局域网)
客户端向目标VIP发送请求,负载均衡器接收
负载均衡器根据负载均衡算法选择后端真实服务器,不修改也不封装IP报文,而是将数据帧的MAC地址改为后端真实服务器的MAC地址,然后在局域网上发送
后端真实服务器收到这个帧,解封装后发现目标IP与本机匹配(事先绑定了VIP),于是处理这个报文。随后重新封装报文,将响应报文通过lo接口传送给物理网卡然后向外发出
客户端将收到回复报文。客户端认为得到正常的服务,而不会知道是哪一台服务器处理的
如果跨网段,则报文通过路由器经由 internet 返回给用户
1.3 Keepalived概述
- 支持故障自动切换(Failover)
- 支持节点健康状态检查(Health Checking)
- 判断LVS负载调度器、节点服务器的可用性,当master主机出现故障及时切换到backup节点保证业务正常,当 master 故障主机恢复后将其重新加入群集并且业务重新切换回 master 节点。
1.4、Keepalived实现原理剖析
- keepalived采用VRRP热备份协议实现Linux 服务器的多机热备功能
- VRRP(虚拟路由冗余协议)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份组,通过共用的虚拟IP地址对外提供服务
- 每个热备组内同时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,则其他路由器会根据设置的优先级自动接替虚拟IP地址,继续提供服务
二、DR模式+keepalived实操
2.1、DR模式配置
2.1.1、配置环境
lvs1:ens33:192.168.152.130
ens33:0:192.168.152.152
lvs2:ens33:192.168.152.129
ens33:0:192.168.152.152
web1:ens33:192.168.152.128
lo:0:192.168.152.152
web2:ens33:192.168.152.127
lo:0:192.168.152.152
client:192.168.152.12
#首先四台虚拟机都先统一一下时钟服务器
yum install ntp -y
yum -y install ntpdate ntp
ntpdate ntp.aliyun.com
2.1.2 配置lvs服务器:
第一台lvs服务器:
[root@lvs1 ~]# yum -y install ipvsadm keepalived
[root@lvs1 ~]# modprobe ip_vs
[root@lvs1 ~]# cat /proc/net/ip_vs
IP Virtual Server version 1.2.1 (size=4096)
Prot LocalAddress:Port Scheduler Flags
-> RemoteAddress:Port Forward Weight ActiveConn InActConn
##配置VIP
[root@lvs1 ~]# cd /etc/sysconfig/network-scripts/
[root@lvs1 network-scripts]# cp -p ifcfg-ens33 ifcfg-ens33:0
[root@lvs1 network-scripts]# vim ifcfg-ens33:0
#删除原本内容,添加以下内容
DEVICE=ens33:0
ONBOOT=yes
IPADDR=192.168.152.152
NETMASK=255.255.255.255
[root@lvs1 network-scripts]# ifup ens33:0
#开启虚拟网卡
[root@lvs1 network-scripts]# ifconfig ens33:0
ens33:0: flags=4163<UP,BROADCAST,RUNNING,MULTICAST> mtu 1500
inet 192.168.152.152 netmask 255.255.255.255 broadcast 192.168.152.152
ether 00:0c:29:16:8d:76 txqueuelen 1000 (Ethernet)
# 设置proc参数,关闭linux内核参数,关闭转发和重定向
[root@lvs1 network-scripts]# cd
[root@lvs1 ~]# vim /etc/sysctl.conf
#调整内核参数,在后面插入以下内容
net.ipv4.ip_forward = 0 #关闭路由转发
net.ipv4.conf.all.send_redirects = 0 # 关闭所有重定向
net.ipv4.conf.default.send_redirects = 0 #关闭默认重定向
net.ipv4.conf.ens33.send_redirects = 0 #关闭ens33网卡重定向
[root@lvs1 ~]# sysctl -p
#刷新内核文件
net.ipv4.ip_forward = 0
net.ipv4.conf.all.send_redirects = 0
net.ipv4.conf.default.send_redirects = 0
net.ipv4.conf.ens33.send_redirects = 0
#开启ipvsadm
[root@lvs1 ~]# ipvsadm-save > /etc/sysconfig/ipvsadm
#启动负载均衡策略
[root@lvs1 ~]# systemctl start ipvsadm
#开启服务
[root@lvs1 ~]# systemctl status ipvsadm
● ipvsadm.service - Initialise the Linux Virtual Server
Loaded: loaded (/usr/lib/systemd/system/ipvsadm.service; disabled; vendor preset: disabled)
Active: active (exited) since 五 2021-07-30 23:52:24 CST; 10s ago
#用脚本创建ipvsadm规则
[root@lvs1 ~]# cd /opt
[root@lvs1 opt]# vim gz.sh
#配置负载均衡分配策略
#!/bin/bash
ipvsadm -C
ipvsadm -A -t 192.168.152.152:80 -s rr
ipvsadm -a -t 192.168.152.152:80 -r 192.168.152.128:80 -g
ipvsadm -a -t 192.168.152.152:80 -r 192.168.152.127:80 -g
ipvsadm
[root@lvs1 opt]# chmod +x gz.sh
[root@lvs1 opt]# bash gz.sh
IP Virtual Server version 1.2.1 (size=4096)
Prot LocalAddress:Port Scheduler Flags
-> RemoteAddress:Port Forward Weight ActiveConn InActConn
TCP lvs1:http rr
-> 192.168.152.127:http Route 1 0 0
-> 192.168.152.128:http Route 1 0 0
第二台lvs服务器:
[root@lvs2 ~]# yum -y install ipvsadm keepalived
[root@lvs2 ~]# modprobe ip_vs
[root@lvs2 ~]# cat /proc/net/ip_vs
IP Virtual Server version 1.2.1 (size=4096)
Prot LocalAddress:Port Scheduler Flags
-> RemoteAddress:Port Forward Weight ActiveConn InActConn
[root@lvs2 ~]# cd /etc/sysconfig/network-scripts
[root@lvs2 network-scripts]# cp -p ifcfg-ens33 ifcfg-ens33:0
[root@lvs2 network-scripts]# vim ifcfg-ens33:0
DEVICE=ens33:0
ONBOOT=yes
IPADDR=192.168.152.152
NETMASK=255.255.255.255
[root@lvs2 network-scripts]# vim /etc/sysctl.conf
net.ipv4.ip_forward = 0 #关闭路由转发
net.ipv4.conf.all.send_redirects = 0 # 关闭所有重定向
net.ipv4.conf.default.send_redirects = 0 #关闭默认重定向
net.ipv4.conf.ens33.send_redirects = 0 #关闭ens33网卡重定向
[root@lvs2 network-scripts]# ipvsadm-save > /etc/sysconfig/ipvsadm
[root@lvs2 network-scripts]# systemctl start ipvsadm
[root@lvs2 network-scripts]# vim /opt/gz.sh
#!/bin/bash
ipvsadm -C
ipvsadm -A -t 192.168.152.152:80 -s rr
ipvsadm -a -t 192.168.152.152:80 -r 192.168.152.128:80 -g
ipvsadm -a -t 192.168.152.152:80 -r 192.168.152.127:80 -g
ipvsadm
[root@lvs2 network-scripts]# chmod +x /opt/gz.sh
[root@lvs2 network-scripts]# bash /opt/gz.sh
IP Virtual Server version 1.2.1 (size=4096)
Prot LocalAddress:Port Scheduler Flags
-> RemoteAddress:Port Forward Weight ActiveConn InActConn
TCP 192.168.152.152:http rr
-> 192.168.152.127:http Route 1 0 0
-> 192.168.152.128:http Route 1 0 0
2.1.3 配置web服务器:
web1服务器:
[root@web1 ~]# cd /etc/sysconfig/network-scripts/
[root@web1 network-scripts]# cp -p ifcfg-lo ifcfg-lo:0
[root@web1 network-scripts]# vim ifcfg-lo:0
DEVICE=lo:0
IPADDR=192.168.152.152
NETMASK=255.255.255.255
# If you're having problems with gated making 127.0.0.0/8 a martian,
# you can change this to something else (255.255.255.255, for example)
ONBOOT=yes
[root@web1 network-scripts]# ifup lo:0
[root@web1 network-scripts]# ifconfig lo:0
lo:0: flags=73<UP,LOOPBACK,RUNNING> mtu 65536
inet 192.168.152.152 netmask 255.255.255.255
loop txqueuelen 1000 (Local Loopback)
#禁锢路由
[root@web1 network-scripts]# route add -host 192.168.152.152 dev lo:0
[root@web1 network-scripts]# route -n
Kernel IP routing table
Destination Gateway Genmask Flags Metric Ref Use Iface
0.0.0.0 192.168.152.2 0.0.0.0 UG 0 0 0 ens33
0.0.0.0 192.168.152.2 0.0.0.0 UG 102 0 0 ens33
169.254.0.0 0.0.0.0 255.255.0.0 U 1002 0 0 ens33
192.168.122.0 0.0.0.0 255.255.255.0 U 0 0 0 virbr0
192.168.152.0 0.0.0.0 255.255.255.0 U 102 0 0 ens33
192.168.152.152 0.0.0.0 255.255.255.255 UH 0 0 0 lo
#这里也可以进入配置文件进行永久的禁锢路由
[root@web1 network-scripts]# vim /etc/rc.local
#在最后一行添加如下内容即可
/sbin/route add -host 192.168.152.152 dev lo:0
#下载安装httpd
[root@web1 ~]# yum install -y httpd
[root@web1 ~]# vim /etc/sysctl.conf
#调整内核的ARP响应参数以阻止更新VIP的MAC地址,避免冲突
net.ipv4.conf.lo.arp_ignore = 1
net.ipv4.conf.lo.arp_announce = 2
net.ipv4.conf.all.arp_ignore = 1
net.ipv4.conf.all.arp_announce = 2
[root@web1 ~]#
[root@web1 ~]# sysctl -p
net.ipv4.conf.lo.arp_ignore = 1
net.ipv4.conf.lo.arp_announce = 2
net.ipv4.conf.all.arp_ignore = 1
net.ipv4.conf.all.arp_announce = 2
[root@web1 ~]# systemctl start httpd
#开启服务
[root@web1 ~]# vim /var/www/html/index.html
<html>
<body>
<meta http-equiv="Content-Type" content="text/html;charset=utf-8">
<h1>this is web1</h1>
</body>
</html>
web2服务器:
[root@web2 ~]# cd /etc/sysconfig/network-scripts/
[root@web2 network-scripts]# cp -p ifcfg-lo ifcfg-lo:0
[root@web2 network-scripts]# vim ifcfg-lo:0
DEVICE=lo:0
IPADDR=192.168.152.152
NETMASK=255.255.255.255
# If you're having problems with gated making 127.0.0.0/8 a martian,
# you can change this to something else (255.255.255.255, for example)
ONBOOT=yes
[root@web2 network-scripts]# ifup ifcfg-lo:0
[root@web2 network-scripts]# ifconfig lo:0
[root@web2 network-scripts]# route add -host 192.168.152.152 dev lo:0
[root@web2 network-scripts]# route -n
Kernel IP routing table
Destination Gateway Genmask Flags Metric Ref Use Iface
0.0.0.0 192.168.152.2 0.0.0.0 UG 100 0 0 ens33
192.168.122.0 0.0.0.0 255.255.255.0 U 0 0 0 virbr0
192.168.152.0 0.0.0.0 255.255.255.0 U 100 0 0 ens33
192.168.152.152 0.0.0.0 255.255.255.255 UH 0 0 0 lo
[root@web2 network-scripts]#
[root@web2 ~]# yum install -y httpd
[root@web1 ~]# vim /etc/sysctl.conf
net.ipv4.conf.lo.arp_ignore = 1
net.ipv4.conf.lo.arp_announce = 2
net.ipv4.conf.all.arp_ignore = 1
net.ipv4.conf.all.arp_announce = 2
[root@web1 ~]#
[root@web1 ~]# sysctl -p
net.ipv4.conf.lo.arp_ignore = 1
net.ipv4.conf.lo.arp_announce = 2
net.ipv4.conf.all.arp_ignore = 1
net.ipv4.conf.all.arp_announce = 2
[root@web2 ~]# systemctl start httpd
[root@web2 ~]# vim /var/www/html/index.html
<html>
<body>
<meta http-equiv="Content-Type" content="text/html;charset=utf-8">
<h1>this is web2</h1>
</body>
</html>
2.1.4 进行测试轮询是否成功
此时可以在浏览器上查看网页(不断刷新),同时在负载调度器上实时观察
[root@lvs1 ~]# watch -n 1 ipvsadm -Lnc
2.2 部署安装Keepalived
第一台lvs服务器:
[root@lvs1 ~]# vim /etc/keepalived/keepalived.conf
global_defs { #定义全局参数
router_id lvs1 #热备组内的设备名称不能一致,备设为lvs2
}
vrrp_instance vi_1 { #定义VRRP热备实例参数
state MASTER #指定热备状态,主为master,备为backup
interface ens33 #指定承载vip地址的物理接口
virtual_router_id 51 #指定虚拟路由器的ID号,每个热备组保持一致
priority 110 #指定优先级,数值越大越优先,备设为100
advert_int 1
authentication {
auth_type PASS
auth_pass 6666
}
virtual_ipaddress { #指定集群VIP地址
192.168.152.152
}
}
#指定虚拟服务器地址vip,端口,定义虚拟服务器和web服务器池参数
virtual_server 192.168.152.152 80 {
lb_algo rr #指定调度算法,轮询(rr)
lb_kind DR #指定集群工作模式,直接路由DR
persistence_timeout 6 #健康检查的间隔时间
protocol TCP #应用服务采用的是TCP协议
#指定第一个web节点的地址,端口
real_server 192.168.152.128 80 {
weight 1 #节点权重
TCP_CHECK {
connect_port 80 #添加检查的目标端口
connect_timeout 3 #添加连接超时
nb_get_retry 3 #添加重试次数
delay_before_retry 3 #添加重试间隔
}
}
#指定第二个web节点的地址,端口
real_server 192.168.152.127 80 {
weight 1
TCP_CHECK {
connect_port 80
connect_timeout 3
nb_get_retry 3
delay_before_retry 3
}
}
}
[root@lvs1 ~]# systemctl start keepalived.service
#开启服务
[root@lvs1 ~]# systemctl status keepalived.service
● keepalived.service - LVS and VRRP High Availability Monitor
Loaded: loaded (/usr/lib/systemd/system/keepalived.service; disabled; vendor preset: disabled)
Active: active (running) since 六 2021-07-31 01:13:04 CST; 47s ago
第二台lvs服务器:
[root@lvs2 ~]# vim /etc/keepalived/keepalived.conf
global_defs { #定义全局参数
router_id lvs2 #热备组内的设备名称不能一致,备设为lvs2
}
vrrp_instance vi_1 { #定义VRRP热备实例参数
state MASTER #指定热备状态,主为master,备为backup
interface ens33 #指定承载vip地址的物理接口
virtual_router_id 51 #指定虚拟路由器的ID号,每个热备组保持一致
priority 100 #指定优先级,数值越大越优先,备设为100
advert_int 1
authentication {
auth_type PASS
auth_pass 6666
}
virtual_ipaddress { #指定集群VIP地址
192.168.152.152
}
}
#指定虚拟服务器地址vip,端口,定义虚拟服务器和web服务器池参数
virtual_server 192.168.152.152 80 {
lb_algo rr #指定调度算法,轮询(rr)
lb_kind DR #指定集群工作模式,直接路由DR
persistence_timeout 6 #健康检查的间隔时间
protocol TCP #应用服务采用的是TCP协议
#指定第一个web节点的地址,端口
real_server 192.168.152.128 80 {
weight 1 #节点权重
TCP_CHECK {
connect_port 80 #添加检查的目标端口
connect_timeout 3 #添加连接超时
nb_get_retry 3 #添加重试次数
delay_before_retry 3 #添加重试间隔
}
}
#指定第二个web节点的地址,端口
real_server 192.168.152.127 80 {
weight 1
TCP_CHECK {
connect_port 80
connect_timeout 3
nb_get_retry 3
delay_before_retry 3
}
}
}
[root@lvs2 ~]# systemctl start keepalived.service
[root@lvs2 ~]# systemctl status keepalived.service
● keepalived.service - LVS and VRRP High Availability Monitor
Loaded: loaded (/usr/lib/systemd/system/keepalived.service; disabled; vendor preset: disabled)
Active: active (running) since 六 2021-07-31 01:17:06 CST; 6s ago
2.2.1 模拟lvs1 故障,测试vip是否自己选择漂移
此时在LVS-02上用“ip a”看不到VIP地址,假设LVS-01发生故障(关闭keepalived),再查看LVS-02的IP地址详细信息
这时候输入命令使lvs1宕机,查看效果:
可以看到lvs的地址变化,VIP 已经从主漂移到了备上面,证明成功
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