环境：
- 202.106.0.17：as Client
- 202.106.0.27: as router
- 192.168.205.37: as lvs1
- 192.168.205.47: as lvs2
- 192.168.205.57: as websrv1
- 192.168.205.67: as websrv2
- 192.168.205.77: as websrv3
- 192.168.205.87: as websrv4
注：所有操作系统默认停用firewalld,iptable为空,关闭selinux
版本：
- OS: centos 7 1810 with mini install
- keepalived
- httpd
目地：
使用keepalived 监控四台web服务器，两台为一组，各使用一个虚拟IP地址，lvs1为vip1的主vip2的从，lvs2为vip2的主，vip1的从，互相主备, 并使用lvs做为负载均衡，并能自动的发现服务down机并自动移除故障主机，从而实现无故障调度。
配置router
- 开启路由转发功能
[root@router data]#ech 1 > /proc/sys/net/ipv4/ip_forward - 增加一个10.1.1.1在router的eth1上, 由于我要到lvs1和lvs2服务器时必须有路由，由于是两个主机的虚拟Ip是很有可能飘移，所以当其中一台down时无法确定在哪台主机上，为了安全不加路由，直接用IP直连。
[root@router data]#ip a a 10.1.1.1/24 dev eth0:1先配置四台real server
-
在app1的两台服务器192.168.205.57/67上运行如下脚本
[root@websrv1 data]#cat lvs_dr_rs.sh #!/bin/bash vip=10.1.1.100 gateway=192.168.205.27 mask='24' dev=lo:1 rpm -q httpd &> /dev/null || yum -y install httpd &>/dev/null service httpd start &> /dev/null && echo "The httpd Server is Ready!" echo "this is `hostname`" > /var/www/html/index.html case $1 in start) echo 1 > /proc/sys/net/ipv4/conf/all/arp_ignore echo 1 > /proc/sys/net/ipv4/conf/lo/arp_ignore echo 2 > /proc/sys/net/ipv4/conf/all/arp_announce echo 2 > /proc/sys/net/ipv4/conf/lo/arp_announce ip a a $vip/$mask dev $dev #broadcast $vip up ip route add default via $gateway dev eth0 #route add -host $vip dev $dev echo "The RS Server is Ready!" ;; stop) systemctl restart network echo 0 > /proc/sys/net/ipv4/conf/all/arp_ignore echo 0 > /proc/sys/net/ipv4/conf/lo/arp_ignore echo 0 > /proc/sys/net/ipv4/conf/all/arp_announce echo 0 > /proc/sys/net/ipv4/conf/lo/arp_announce echo "The RS Server is Canceled!" ;; *) echo "Usage: $(basename $0) start|stop" exit 1 ;; esac -
在app2的两台服务器192.168.205.77/87上运行如下脚本
[root@websrv3 data]#cat lvs_dr_rs.sh #!/bin/bash vip=10.1.1.200 gateway=192.168.205.27 mask='24' dev=lo:1 rpm -q httpd &> /dev/null || yum -y install httpd &>/dev/null service httpd start &> /dev/null && echo "The httpd Server is Ready!" echo "this is `hostname`" > /var/www/html/index.html case $1 in start) echo 1 > /proc/sys/net/ipv4/conf/all/arp_ignore echo 1 > /proc/sys/net/ipv4/conf/lo/arp_ignore echo 2 > /proc/sys/net/ipv4/conf/all/arp_announce echo 2 > /proc/sys/net/ipv4/conf/lo/arp_announce ip address add $vip/$mask dev $dev #broadcast $vip up ip route add default via $gateway dev eth0 #route add -host $vip dev $dev echo "The RS Server is Ready!" ;; stop) systemctl restart network echo 0 > /proc/sys/net/ipv4/conf/all/arp_ignore echo 0 > /proc/sys/net/ipv4/conf/lo/arp_ignore echo 0 > /proc/sys/net/ipv4/conf/all/arp_announce echo 0 > /proc/sys/net/ipv4/conf/lo/arp_announce echo "The RS Server is Canceled!" ;; *) echo "Usage: $(basename $0) start|stop" exit 1 ;; esac在两台lvs上做同样的动（除特别说明）
- 安装httpd服务，将sorry server放在本地的两台主机中
yum install httpd echo server is under maitenance > /var/www/html/index.html - 一定要加默认路由到router,如果加正确可以工作，但sorry server不会正常
ip route add default via 192.168.205.27 dev eth0 - 为了访问方便最好是将两个lvs服务器之间做ssh key验证，用下面的方法就不用在47上再做一次了，真接实现互认证
ssh-keygen scp -r /root/.ssh 192.168.205.47:/root - 最好将host文件加入两台主机名称解析
vi /etc/hosts 192.168.205.37 websrv1 192.168.205.47 websrv2 scp /etc/hosts 192.168.205.47:/etc - 安装keepalive, 为了能看清如何加的lvs策略，我们把iplvadm也装上
yum install keepalived ipvsadm - 在lvs1上修改配置文件
[root@lsv1 ~]#vi /etc/keepalived/keepalived.conf ! Configuration File for keepalived global_defs { notification_email { root@localhost } notification_email_from keepalive@localhost smtp_server 127.0.0.1 smtp_connect_timeout 30 router_id LVS1 vrrp_mcast_group4 224.0.0.100 } vrrp_instance VI_1 { state MASTER interface eth0 virtual_router_id 37 priority 100 advert_int 1 authentication { auth_type PASS auth_pass centos } virtual_ipaddress { 10.1.1.100/24 dev eth0 label eth0:0 } } vrrp_instance VI_2 { state BACKUP interface eth0 virtual_router_id 47 priority 80 advert_int 1 authentication { auth_type PASS auth_pass centos } virtual_ipaddress { 10.1.1.200/24 dev eth0 label eth0:1 } } virtual_server 10.1.1.100 80 { delay_loop 6 lb_algo rr lb_kind DR protocol TCP sorry_server 127.0.0.1 80 real_server 192.168.205.57 80 { weight 1 HTTP_GET { url { path / status_code 200 } connect_timeout 1 nb_get_retry 3 delay_before_retry 1 } } real_server 192.168.205.67 80 { weight 1 HTTP_GET { url { path / status_code 200 } connect_timeout 1 nb_get_retry 3 delay_before_retry 1 } } } virtual_server 10.1.1.200 80 { delay_loop 6 lb_algo rr lb_kind DR protocol TCP sorry_server 127.0.0.1 80 real_server 192.168.205.77 80 { weight 1 HTTP_GET { url { path / status_code 200 } connect_timeout 1 nb_get_retry 3 delay_before_retry 1 } } real_server 192.168.205.87 80 { weight 1 HTTP_GET { url { path / status_code 200 } connect_timeout 1 nb_get_retry 3 delay_before_retry 1 } } } 11. 为了方便将lsv1的keepalive.conf复制到lvs2上，并进行修改 [root@lvs2 ~]#vi /etc/keepalived/keepalived.conf ! Configuration File for keepalived global_defs { notification_email { root@localhost } notification_email_from keepalive@localhost smtp_server 127.0.0.1 smtp_connect_timeout 30 router_id LVS2 vrrp_mcast_group4 224.0.0.100 } vrrp_instance VI_1 { state BACKUP interface eth0 virtual_router_id 37 priority 80 advert_int 1 authentication { auth_type PASS auth_pass centos } virtual_ipaddress { 10.1.1.100/24 dev eth0 label eth0:0 } } vrrp_instance VI_2 { state MASTER interface eth0 virtual_router_id 47 priority 100 advert_int 1 authentication { auth_type PASS auth_pass centos } virtual_ipaddress { 10.1.1.200/24 dev eth0 label eth0:1 } } virtual_server 10.1.1.100 80 { delay_loop 6 lb_algo rr lb_kind DR protocol TCP sorry_server 127.0.0.1 80 real_server 192.168.205.57 80 { weight 1 HTTP_GET { url { path / status_code 200 } connect_timeout 1 nb_get_retry 3 delay_before_retry 1 } } real_server 192.168.205.67 80 { weight 1 HTTP_GET { url { path / status_code 200 } connect_timeout 1 nb_get_retry 3 delay_before_retry 1 } } } virtual_server 10.1.1.200 80 { delay_loop 6 lb_algo rr lb_kind DR protocol TCP sorry_server 127.0.0.1 80 real_server 192.168.205.77 80 { weight 1 HTTP_GET { url { path / status_code 200 } connect_timeout 1 nb_get_retry 3 delay_before_retry 1 } } real_server 192.168.205.87 80 { weight 1 HTTP_GET { url { path / status_code 200 } connect_timeout 1 nb_get_retry 3 delay_before_retry 1 } } } - 起动keepalived服务
systemctl start keepalived - 在lvs1看到状态为RR调度
[root@lsv1 ~]#ipvsadm -Ln IP Virtual Server version 1.2.1 (size=4096) Prot LocalAddress:Port Scheduler Flags -> RemoteAddress:Port Forward Weight ActiveConn InActConn TCP 10.1.1.100:80 rr -> 192.168.205.57:80 Route 1 0 0 -> 192.168.205.67:80 Route 1 0 0 TCP 10.1.1.200:80 rr -> 192.168.205.77:80 Route 1 0 0 -> 192.168.205.87:80 Route 1 0 0 - 在lvs1中看到只一10.1.1.100IP， 在Lvs2中会看到只有10.1.1.200IP
[root@lsv1 ~]#ip a 2: eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP group default qlen 1000 link/ether 00:0c:29:56:e1:ea brd ff:ff:ff:ff:ff:ff inet 192.168.205.37/24 brd 192.168.205.255 scope global noprefixroute eth0 valid_lft forever preferred_lft forever inet 10.1.1.100/24 scope global eth0:0 valid_lft forever preferred_lft forever inet6 fe80::20c:29ff:fe56:e1ea/64 scope link noprefixroute valid_lft forever preferred_lft forever [root@lvs2 ~]#ip a 2: eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP group default qlen 1000 link/ether 00:0c:29:37:f9:93 brd ff:ff:ff:ff:ff:ff inet 192.168.205.47/24 brd 192.168.205.255 scope global noprefixroute eth0 valid_lft forever preferred_lft forever inet 10.1.1.200/24 scope global eth0:1 valid_lft forever preferred_lft forever inet6 fe80::20c:29ff:fe37:f993/64 scope link noprefixroute valid_lft forever preferred_lft forever测试
- 在client上运行一个循环进行测试
[root@client ~]#while : ;do curl 10.1.1.100; sleep 0.5; done this is websrv1 this is websrv2 this is websrv1 this is websrv2 this is websrv1 this is websrv2 [root@client ~]#while : ;do curl 10.1.1.200; sleep 0.5; done this is websrv4 this is websrv3 this is websrv4 this is websrv3 this is websrv4 - 停掉web1，再测试，发现只会调度到web2
[root@websrv1 data]#systemctl stop httpd [root@client ~]#while : ;do curl 10.1.1.100; sleep 0.5; done this is websrv2 this is websrv2 this is websrv2 this is websrv2 this is websrv2 - 停掉web2，再测试，发现sorry server带替工作，并在lvs1上可以看到127.0.0.1加载
[root@websrv2 ~]#systemctl stop httpd [root@client ~]#while : ;do curl 10.1.1.100; sleep 0.5; done server is under maitenance server is under maitenance server is under maitenance server is under maitenance [root@lsv1 ~]#ipvsadm -Ln IP Virtual Server version 1.2.1 (size=4096) Prot LocalAddress:Port Scheduler Flags -> RemoteAddress:Port Forward Weight ActiveConn InActConn TCP 10.1.1.100:80 rr -> 127.0.0.1:80 Route 1 0 4 TCP 10.1.1.200:80 rr -> 192.168.205.77:80 Route 1 0 0 -> 192.168.205.87:80 Route 1 0 0 - 恢复两个websrv1 和websrv2,并停掉lvs2, 发现没有影响，但可以看到两个vip全部回到lvs1上
[root@websrv1 ~]#systemctl start httpd [root@websrv2 ~]#systemctl start httpd [root@lvs2 ~]#systemctl stop keepalived [root@client ~]#while : ;do curl 10.1.1.100; sleep 0.5; done this is websrv2 this is websrv1 this is websrv2 this is websrv1 [root@client ~]#while : ;do curl 10.1.1.200; sleep 0.5; done this is websrv3 this is websrv4 this is websrv3 this is websrv4 [root@lsv1 ~]#ip a 2: eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP group default qlen 1000 link/ether 00:0c:29:56:e1:ea brd ff:ff:ff:ff:ff:ff inet 192.168.205.37/24 brd 192.168.205.255 scope global noprefixroute eth0 valid_lft forever preferred_lft forever inet 10.1.1.100/24 scope global eth0:0 valid_lft forever preferred_lft forever inet 10.1.1.200/24 scope global secondary eth0:1 valid_lft forever preferred_lft forever inet6 fe80::20c:29ff:fe56:e1ea/64 scope link noprefixroute valid_lft forever preferred_lft forever - 将lvs2恢复状态，因为有抢占功能又回到原来的主和备份上
[root@client ~]#while : ;do curl 10.1.1.100; sleep 0.5; done this is websrv2 this is websrv1 this is websrv2 [root@client ~]#while : ;do curl 10.1.1.200; sleep 0.5; done this is websrv4 this is websrv3 this is websrv4 [root@lsv1 ~]#ip a 2: eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP group default qlen 1000 link/ether 00:0c:29:56:e1:ea brd ff:ff:ff:ff:ff:ff inet 192.168.205.37/24 brd 192.168.205.255 scope global noprefixroute eth0 valid_lft forever preferred_lft forever inet 10.1.1.100/24 scope global eth0:0 valid_lft forever preferred_lft forever inet6 fe80::20c:29ff:fe56:e1ea/64 scope link noprefixroute valid_lft forever preferred_lft forever [root@lvs2 ~]#ip a 2: eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP group default qlen 1000 link/ether 00:0c:29:37:f9:93 brd ff:ff:ff:ff:ff:ff inet 192.168.205.47/24 brd 192.168.205.255 scope global noprefixroute eth0 valid_lft forever preferred_lft forever inet 10.1.1.200/24 scope global eth0:1 valid_lft forever preferred_lft forever inet6 fe80::20c:29ff:fe37:f993/64 scope link noprefixroute valid_lft forever preferred_lft forever
来源：https://blog.51cto.com/127601/2427468