配置Keepalived双实例高可用Nginx
我们知道Keepalived原生设计目的是为了高可用LVS集群的，但Keepalived除了可以高可用LVS服务之外，还可以基于vrrp_script和track_script高可用其它服务，如Nginx等。本篇主要演示如何使用Keepalived高可用Nginx服务（双实例），关于vrrp_script、track_script的更多介绍可以见上一篇博客《Keepalived学习总结》。实验要求 ==> 实现Keepalived基于vrrp_script、track_script高可用Nginx服务，要求配置为双实例，两个vrrp实例的VIP分别为192.168.10.77、192.168.10.78，可以分别将其配置在网卡别名上。
实验环境 ==> CentOS 7.x
实验目的 ==> 实现Keepalived双实例高可用Nginx服务
实验主机 ==> 192.168.10.6（主机名：node1）、192.168.10.8（主机名：node2）
实验前提 ==> 高可用对之间时间同步（可通过周期性任务来实现）
实验操作如下。
1、编辑Keepalived配置文件
https://s4.运维网.com/wyfs02/M00/9D/FD/wKiom1mJoP3wXR9MAAhpKrodjuU754.jpg
2、在两个节点上分别使用yum安装Nginx，并启动Web服务
(1) 在node1（192.168.10.6）上
# yum -y install nginx
# systemctl start nginx.service
# ss -tnl | grep :80
LISTEN 0 128 *:80 *:*
LISTEN 0 128 :::80 :::*
(2) 在node2（192.168.10.8）上
# yum -y install nginx
# systemctl start nginx.service
# ss -tnl | grep :80
LISTEN 0 128 *:80 *:*
3、在两个节点上分别启动Keepalived服务
(1) 在node1（192.168.10.6）上
# systemctl start keepalived
# ifconfig
ens33: flags=4163mtu 1500
inet 192.168.10.6netmask 255.255.255.0broadcast 192.168.10.255
ether 00:0c:29:f7:b3:4etxqueuelen 1000(Ethernet)
RX packets 46064bytes 21104876 (20.1 MiB)
RX errors 0dropped 0overruns 0frame 0
TX packets 43548bytes 3735943 (3.5 MiB)
TX errors 0dropped 0 overruns 0carrier 0collisions 0
ens33:0: flags=4163mtu 1500
inet 192.168.10.77netmask 255.255.255.255broadcast 0.0.0.0
ether 00:0c:29:f7:b3:4etxqueuelen 1000(Ethernet)
lo: flags=73mtu 65536
inet 127.0.0.1netmask 255.0.0.0
inet6 ::1prefixlen 128scopeid 0x10
looptxqueuelen 0(Local Loopback)
RX packets 195bytes 12522 (12.2 KiB)
RX errors 0dropped 0overruns 0frame 0
TX packets 195bytes 12522 (12.2 KiB)
TX errors 0dropped 0 overruns 0carrier 0collisions 0
(2) 在node2（192.168.10.8）上
# systemctl start keepalived
# ifconfig
ens34: flags=4163mtu 1500
inet 192.168.10.8netmask 255.255.255.0broadcast 192.168.10.255
ether 00:0c:29:ef:52:87txqueuelen 1000(Ethernet)
RX packets 60646bytes 17433464 (16.6 MiB)
RX errors 0dropped 0overruns 0frame 0
TX packets 29539bytes 2636829 (2.5 MiB)
TX errors 0dropped 0 overruns 0carrier 0collisions 0
ens34:1: flags=4163mtu 1500
inet 192.168.10.78netmask 255.255.255.255broadcast 0.0.0.0
ether 00:0c:29:ef:52:87txqueuelen 1000(Ethernet)
lo: flags=73mtu 65536
inet 127.0.0.1netmask 255.0.0.0
inet6 ::1prefixlen 128scopeid 0x10
looptxqueuelen 0(Local Loopback)
RX packets 319bytes 20447 (19.9 KiB)
RX errors 0dropped 0overruns 0frame 0
TX packets 319bytes 20447 (19.9 KiB)
TX errors 0dropped 0 overruns 0carrier 0collisions 0 可以发现，因为在第一个vrrp实例（VIP为192.168.10.77）中，node1节点为主节点，因此该VIP配置在node1上；而在第二个vrrp实例（VIP为192.168.10.78）中，node2节点为主节点，因此该VIP配置在node2上。
4、人为制造故障进行测试
(1) 在node2上杀死nginx进程，查看第二个vrrp实例的VIP（192.168.10.78）是否会漂移至node1。
# killall nginx
#查看日志
# tail /var/log/messages
...（其他省略）...
Aug8 16:29:28 node2 Keepalived_vrrp: VRRP_Script(chk_nginx) failed
Aug8 16:29:30 node2 Keepalived_vrrp: VRRP_Instance(VI_2) Received higher prio advert
Aug8 16:29:30 node2 Keepalived_vrrp: VRRP_Instance(VI_2) Entering BACKUP STATE
Aug8 16:29:30 node2 Keepalived_vrrp: VRRP_Instance(VI_2) removing protocol VIPs.
Aug8 16:29:30 node2 Keepalived_healthcheckers: Netlink reflector reports IP 192.168.10.78 removed
#查看node2上的IP地址
# ifconfig
ens34: flags=4163mtu 1500
inet 192.168.10.8netmask 255.255.255.0broadcast 192.168.10.255
ether 00:0c:29:ef:52:87txqueuelen 1000(Ethernet)
RX packets 61483bytes 17487867 (16.6 MiB)
RX errors 0dropped 0overruns 0frame 0
TX packets 29994bytes 2672261 (2.5 MiB)
TX errors 0dropped 0 overruns 0carrier 0collisions 0
lo: flags=73mtu 65536
inet 127.0.0.1netmask 255.0.0.0
inet6 ::1prefixlen 128scopeid 0x10
looptxqueuelen 0(Local Loopback)
RX packets 323bytes 20647 (20.1 KiB)
RX errors 0dropped 0overruns 0frame 0
TX packets 323bytes 20647 (20.1 KiB)
TX errors 0dropped 0 overruns 0carrier 0collisions 0 可以发现第二个vrrp实例的VIP（192.168.10.78）已经从node2上移除。
#查看node1上的IP地址
# ifconfig
ens33: flags=4163mtu 1500
inet 192.168.10.6netmask 255.255.255.0broadcast 192.168.10.255
ether 00:0c:29:f7:b3:4etxqueuelen 1000(Ethernet)
RX packets 46700bytes 21146944 (20.1 MiB)
RX errors 0dropped 0overruns 0frame 0
TX packets 44417bytes 3794925 (3.6 MiB)
TX errors 0dropped 0 overruns 0carrier 0collisions 0
ens33:0: flags=4163mtu 1500
inet 192.168.10.77netmask 255.255.255.255broadcast 0.0.0.0
ether 00:0c:29:f7:b3:4etxqueuelen 1000(Ethernet)
ens33:1: flags=4163mtu 1500
inet 192.168.10.78netmask 255.255.255.255broadcast 0.0.0.0
ether 00:0c:29:f7:b3:4etxqueuelen 1000(Ethernet)
lo: flags=73mtu 65536
inet 127.0.0.1netmask 255.0.0.0
inet6 ::1prefixlen 128scopeid 0x10
looptxqueuelen 0(Local Loopback)
RX packets 199bytes 12722 (12.4 KiB)
RX errors 0dropped 0overruns 0frame 0
TX packets 199bytes 12722 (12.4 KiB)
TX errors 0dropped 0 overruns 0carrier 0collisions 0 此时node1不仅是第一个vrrp实例（VIP为192.168.10.77）的主节点，还是第二个vrrp实例（VIP为192.168.10.78）的主节点。
(2) 在node1上杀死nginx进程，在node2上重新启动nginx进程，查看第一个vrrp实例的VIP（192.168.10.77）和第二个vrrp实例的VIP（192.168.10.78）是否会漂移至node2。
#先在node2上重启nginx进程，此时第二个vrrp实例的VIP（192.168.10.78）应该会重新漂移至node2上
# systemctl restart nginx.service
# ss -tnl | grep :80
LISTEN 0 128 *:80 *:*
# ifconfig
ens34: flags=4163mtu 1500
inet 192.168.10.8netmask 255.255.255.0broadcast 192.168.10.255
ether 00:0c:29:ef:52:87txqueuelen 1000(Ethernet)
RX packets 62438bytes 17551143 (16.7 MiB)
RX errors 0dropped 0overruns 0frame 0
TX packets 30145bytes 2688809 (2.5 MiB)
TX errors 0dropped 0 overruns 0carrier 0collisions 0
ens34:1: flags=4163mtu 1500
inet 192.168.10.78netmask 255.255.255.255broadcast 0.0.0.0
ether 00:0c:29:ef:52:87txqueuelen 1000(Ethernet)
lo: flags=73mtu 65536
inet 127.0.0.1netmask 255.0.0.0
inet6 ::1prefixlen 128scopeid 0x10
looptxqueuelen 0(Local Loopback)
RX packets 331bytes 21047 (20.5 KiB)
RX errors 0dropped 0overruns 0frame 0
TX packets 331bytes 21047 (20.5 KiB)
TX errors 0dropped 0 overruns 0carrier 0collisions 0 果然在意料之中！
#在node1上杀死nginx进程，查看第一个vrrp实例的VIP（192.168.10.77）是否会重新漂移至node2上
# killall nginx # 杀死nginx进程
# tail /var/log/messages # 查看日志
Aug8 16:36:41 node1 Keepalived_vrrp: VRRP_Instance(VI_2) Sending gratuitous ARPs on ens33 for 192.168.10.78
Aug8 16:37:10 node1 Keepalived_vrrp: VRRP_Instance(VI_2) Received higher prio advert
Aug8 16:37:10 node1 Keepalived_vrrp: VRRP_Instance(VI_2) Entering BACKUP STATE
Aug8 16:37:10 node1 Keepalived_vrrp: VRRP_Instance(VI_2) removing protocol VIPs.
Aug8 16:37:10 node1 Keepalived_healthcheckers: Netlink reflector reports IP 192.168.10.78 removed
Aug8 16:38:44 node1 Keepalived_vrrp: VRRP_Script(chk_nginx) failed
Aug8 16:38:45 node1 Keepalived_vrrp: VRRP_Instance(VI_1) Received higher prio advert
Aug8 16:38:45 node1 Keepalived_vrrp: VRRP_Instance(VI_1) Entering BACKUP STATE
Aug8 16:38:45 node1 Keepalived_vrrp: VRRP_Instance(VI_1) removing protocol VIPs.
Aug8 16:38:45 node1 Keepalived_healthcheckers: Netlink reflector reports IP 192.168.10.77 removed
# ifconfig # 查看IP地址
ens33: flags=4163mtu 1500
inet 192.168.10.6netmask 255.255.255.0broadcast 192.168.10.255
ether 00:0c:29:f7:b3:4etxqueuelen 1000(Ethernet)
RX packets 47288bytes 21191119 (20.2 MiB)
RX errors 0dropped 0overruns 0frame 0
TX packets 45193bytes 3854623 (3.6 MiB)
TX errors 0dropped 0 overruns 0carrier 0collisions 0
lo: flags=73mtu 65536
inet 127.0.0.1netmask 255.0.0.0
inet6 ::1prefixlen 128scopeid 0x10
looptxqueuelen 0(Local Loopback)
RX packets 215bytes 13522 (13.2 KiB)
RX errors 0dropped 0overruns 0frame 0
TX packets 215bytes 13522 (13.2 KiB)
TX errors 0dropped 0 overruns 0carrier 0collisions 0 两个vrrp实例的VIP都不见了。
#重新查看node2上的IP地址
# ifconfig
ens34: flags=4163mtu 1500
inet 192.168.10.8netmask 255.255.255.0broadcast 192.168.10.255
ether 00:0c:29:ef:52:87txqueuelen 1000(Ethernet)
RX packets 62612bytes 17562546 (16.7 MiB)
RX errors 0dropped 0overruns 0frame 0
TX packets 30521bytes 2712799 (2.5 MiB)
TX errors 0dropped 0 overruns 0carrier 0collisions 0
ens34:0: flags=4163mtu 1500
inet 192.168.10.77netmask 255.255.255.255broadcast 0.0.0.0
ether 00:0c:29:ef:52:87txqueuelen 1000(Ethernet)
ens34:1: flags=4163mtu 1500
inet 192.168.10.78netmask 255.255.255.255broadcast 0.0.0.0
ether 00:0c:29:ef:52:87txqueuelen 1000(Ethernet)
lo: flags=73mtu 65536
inet 127.0.0.1netmask 255.0.0.0
inet6 ::1prefixlen 128scopeid 0x10
looptxqueuelen 0(Local Loopback)
RX packets 335bytes 21247 (20.7 KiB)
RX errors 0dropped 0overruns 0frame 0
TX packets 335bytes 21247 (20.7 KiB)
TX errors 0dropped 0 overruns 0carrier 0collisions 0 两个vrrp实例的VIP都漂移到node2去了。
当然，本配置示例中自定义的vrrp_script过于简单，此处提供一个vrrp_script监控脚本，仅供参考。
# vim /etc/keepalived/vrrp_script.sh
#!/bin/bash
#
server=nginx
restart_server() {
if ! systemctl restart $server &> /dev/null; then
sleep 1
return 0
else
exit 0
fi
}
if ! killall -0 $server &> /dev/null; then
restart_server
restart_server
restart_server
[ $? -ne 0 ] && exit 1 || exit 0
fi 在keepalived.conf配置文件中需要指明脚本路径。
# vim /etc/keepalived/keepalived.conf
...（其他省略）...
vrrp_script chk_nginx {
script "/etc/keepalived/vrrp_script.sh"
interval 2
weight -5
}
...（其他省略）...
实验完成！
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