使用keepalived配置支持Linux集群高可用
Linux集群概述
- 根据功能划分为两大类：高可用和负载均衡
- 高可用集群一般为两台服务器，一台工做，另一台做为冗余，当提供服务的机器宕机，冗余将接替继续提供服务
- 实现高可用的开源软件有：heartbeat、keepalived，推荐使用keepalived
- 负载均衡集群，须要有一台服务器做为分发器，它负责把用户的请求分发给后端的服务器处理，在这个集群里，除了分发器外，就是给用户提供服务的服务器了，这些服务器数量至少为2
- 实现负载均衡的开源软件有LVS、keepalived、haproxy、nginx，商业的有F五、Netscaler
keepalived介绍
- keepalived经过VRRP（Virtual Router Redundancy Protocol,虚拟路由冗余协议）来实现高可用。
- 在这个协议里会将多台功能相同的路由器组成一个小组，这个小组里会有1个master角色和N（N>=1）个backup角色。
- master会经过组播的形式向各个backup发送VRRP协议的数据包，当backup收不到master发来的VRRP数据包时，就会认为master宕机了。此时就须要根据各个backup的优先级来决定谁成为新的mater
- keepalived要有三个模块，分别是core、check和vrrp。其中core模块为keepalived的核心，负责主进程的启动、维护以及全局配置文件的加载和解析，check模块负责健康检查，vrrp模块是来实现VRRP协议的。
针对Nginx服务进行高可用配置
virtual_ipaddress 绑定的ip, 下面简写vipnginx
安装keepalive
master(test-a:134)与backup(centos0: 129)安装keepalivedvim
[root@test-a ~]# yum install -y keepalived [root@centos0 ~]# yum install -y keepalived # 使用yum安装Nginx若是提示找不到对应的安装包，须要安装epel源 [root@centos0 ~]# yum install -y nginx 已加载插件：fastestmirror Loading mirror speeds from cached hostfile * base: mirrors.aliyun.com * extras: mirrors.neusoft.edu.cn * updates: mirrors.cqu.edu.cn 没有可用软件包 nginx。 错误：无须任何处理 [root@centos0 ~]# yum install -y nginx # 再安装
master配置启动服务后端
# 先关闭防火墙
[root@test-a ~]# systemctl stop firewalld.service
[root@test-a ~]# setenforce 0
# 编辑配置文件
[root@test-a ~]# vim /etc/keepalived/keepalived.conf
[root@test-a ~]# cat /etc/keepalived/keepalived.conf
global_defs {
smtp_server 127.0.0.1
smtp_connect_timeout 30
router_id LVS_DEVEL
}
vrrp_script chk_nginx {
script "/usr/local/sbin/check_ng.sh"
interval 3
}
vrrp_instance VI_1 {
state MASTER
interface eno16777736
virtual_router_id 1
priority 100
advert_int 1
authentication {
auth_type PASS
auth_pass test111
}
virtual_ipaddress {
192.168.77.100
}
track_script {
chk_nginx
}
}
[root@test-a ~]# vim /usr/local/sbin/check_ng.sh # 编写对应的检测脚本
[root@test-a ~]# cat /usr/local/sbin/check_ng.sh
#!/bin/bash
#时间变量，用于记录日志
d=`date --date today +%Y%m%d_%H:%M:%S`
#计算nginx进程数量
n=`ps -C nginx --no-heading|wc -l`
#若是进程为0，则启动nginx，而且再次检测nginx进程数量，
#若是还为0，说明nginx没法启动，此时须要关闭keepalived
echo "$d nginx check begin"
if [ $n -eq "0" ]; then
/etc/init.d/nginx start
n2=`ps -C nginx --no-heading|wc -l`
if [ $n2 -eq "0" ]; then
echo "$d nginx down,keepalived will stop" >> /var/log/check_ng.log
systemctl stop keepalived
fi
echo "$d nginx restart ok" >> /var/log/check_ng.log
fi
[root@test-a ~]# chmod 755 /usr/local/sbin/check_ng.sh
[root@test-a ~]# systemctl start keepalived.service
[root@test-a ~]# ps aux|grep keep
root 2841 0.0 0.1 119248 1396 ? Ss 15:13 0:00 /usr/sbin/keepa lived -D
root 2842 0.0 0.3 123448 3136 ? S 15:13 0:00 /usr/sbin/keepa lived -D
root 2843 0.1 0.2 123516 2532 ? S 15:13 0:00 /usr/sbin/keepa lived -D
root 2861 0.0 0.0 112704 972 pts/0 R+ 15:14 0:00 grep --color=au to keep
[root@test-a ~]# ps aux|grep nginx
root 1688 0.0 0.1 46548 1268 ? Ss 15:00 0:00 nginx: master p rocess /usr/local/nginx/sbin/nginx -c /usr/local/nginx/conf/nginx.conf
nobody 1694 0.0 0.3 49036 3900 ? S 15:00 0:00 nginx: worker p rocess
nobody 1695 0.0 0.3 49036 3900 ? S 15:00 0:00 nginx: worker p rocess
root 2911 0.0 0.0 112704 976 pts/0 R+ 15:14 0:00 grep --color=au to nginx
[root@test-a ~]# ip add # 查看绑定的vip地址,ifconfig看不见
1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 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
valid_lft forever preferred_lft forever
inet6 ::1/128 scope host
valid_lft forever preferred_lft forever
2: eno16777736: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast stat e UP qlen 1000
link/ether 00:0c:29:b9:56:99 brd ff:ff:ff:ff:ff:ff
inet 192.168.77.134/24 brd 192.168.77.255 scope global eno16777736
valid_lft forever preferred_lft forever
inet 192.168.77.100/32 scope global eno16777736
valid_lft forever preferred_lft forever
inet 192.168.77.139/24 brd 192.168.77.255 scope global secondary eno16777736 :t
valid_lft forever preferred_lft forever
inet6 fe80::20c:29ff:feb9:5699/64 scope link
valid_lft forever preferred_lft forever
[root@test-a ~]# /etc/init.d/nginx stop # nginx中止后，检测脚本会从新启动
Stopping nginx (via systemctl): [ OK ]
[root@test-a ~]# ps aux|grep keep
root 4508 0.0 0.1 119248 1396 ? Ss 15:21 0:00 /usr/sbin/keepa lived -D
root 4509 0.0 0.3 123448 3120 ? S 15:21 0:00 /usr/sbin/keepa lived -D
root 4510 0.0 0.2 123516 2652 ? S 15:21 0:00 /usr/sbin/keepa lived -D
root 5402 0.0 0.0 112704 976 pts/0 R+ 15:25 0:00 grep --color=au to keep
[root@test-a ~]# ps aux|grep nginx
root 5388 0.0 0.1 46548 1264 ? Ss 15:25 0:00 nginx: master p rocess /usr/local/nginx/sbin/nginx -c /usr/local/nginx/conf/nginx.conf
nobody 5392 0.0 0.3 49036 3900 ? S 15:25 0:00 nginx: worker p rocess
nobody 5393 0.0 0.3 49036 3900 ? S 15:25 0:00 nginx: worker p rocess
root 5428 0.0 0.0 112704 976 pts/0 R+ 15:25 0:00 grep --color=au to nginx
[root@test-a ~]#
backup配置启动服务centos
[root@centos0 ~]# setenforce 0
[root@centos0 ~]# systemctl stop firewalld
[root@centos0 ~]# vim /usr/local/sbin/check_ng.sh
[root@centos0 ~]# cat /usr/local/sbin/check_ng.sh
#!/bin/bash
#时间变量，用于记录日志
d=`date --date today +%Y%m%d_%H:%M:%S`
#计算nginx进程数量
n=`ps -C nginx --no-heading|wc -l`
#若是进程为0，则启动nginx，而且再次检测nginx进程数量，
#若是还为0，说明nginx没法启动，此时须要关闭keepalived
if [ $n -eq "0" ]; then
systemctl start nginx
n2=`ps -C nginx --no-heading|wc -l`
if [ $n2 -eq "0" ]; then
echo "$d nginx down,keepalived will stop" >> /var/log/check_ng.log
systemctl stop keepalived
fi
fi
[root@centos0 ~]# chmod 755 /usr/local/sbin/check_ng.sh
[root@centos0 ~]# vim /etc/keepalived/keepalived.conf
[root@centos0 ~]# cat /etc/keepalived/keepalived.conf
global_defs {
smtp_server 127.0.0.1
smtp_connect_timeout 30
router_id LVS_DEVEL
}
vrrp_script chk_nginx {
script "/usr/local/sbin/check_ng.sh"
interval 3
}
vrrp_instance VI_1 {
state BACKUP
interface eno16777736
virtual_router_id 1
priority 90
advert_int 1
authentication {
auth_type PASS
auth_pass test111
}
virtual_ipaddress {
192.168.77.100
}
track_script {
chk_nginx
}
}
[root@centos0 ~]# ps aux | grep keep
root 4219 0.0 0.0 112656 988 pts/0 R+ 15:46 0:00 grep --color=auto keep
[root@centos0 ~]# ps aux | grep nginx
root 4221 0.0 0.0 112656 988 pts/0 R+ 15:46 0:00 grep --color=auto nginx
# 能够看到，keepalived 和 nginx 都没启动起来，这时若是启动keepalived，nginx也启动起来，说明配置成功
[root@centos0 ~]# systemctl start keepalived
[root@centos0 ~]# ps aux | grep keep
root 4230 0.0 0.1 119100 1376 ? Ss 15:48 0:00 /usr/sbin/keepalived -D
root 4231 0.0 0.3 123268 3096 ? S 15:48 0:00 /usr/sbin/keepalived -D
root 4232 0.0 0.2 123268 2608 ? S 15:48 0:00 /usr/sbin/keepalived -D
root 4262 0.0 0.0 112656 988 pts/0 R+ 15:48 0:00 grep --color=auto keep
[root@centos0 ~]# ps aux | grep nginx # nginx也启动起来啦
root 4256 0.0 0.2 125388 2112 ? Ss 15:48 0:00 nginx: master process /usr/sbin/nginx
nginx 4257 0.0 0.3 125776 3132 ? S 15:48 0:00 nginx: worker process
root 4282 0.0 0.0 112656 992 pts/0 R+ 15:48 0:00 grep --color=auto nginx
浏览器访问测试浏览器
访问master:
bash
访问backup:
服务器
访问绑定的vip:
负载均衡
停掉master上的keepalived，再进行访问测试，发现已经切到backup了oop
[root@test-a ~]# systemctl stop keepalived.service
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