集群介绍
根据功能划分为两大类：高可用和负载均衡
(1)高可用集群通常为两台服务器，台工作，另外一台作为准备，当提供服务的机器宕机，另外一台将接替继续提供服务。
实现高可用的开源软件有：heartbeat,keepalived
(2)负载均衡集群：需要有一台服务器作为分发器，它负责吧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，这些服务器数量最少为2
实现负载均衡的开源软件有LVS，keepalived，haproxy，nginx，商业的有F5，Netscaler
keepalived介绍
heartbeat在centos6上有一些bug，影响实验效果。所以我们不介意使用heartbeat。
keepalived通过VRRP（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，这个小组里会有一个master角色和N（N>=1）个backup角色。
工作原理：mster会通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，此时就需要根据哥哥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，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模块是用来实现VRRP协议的。
用keepalived配置高可用集群
1.准备两台机器
master:192.168.133.88
backup:192.168.133.66
2.两台机.器都安装keepalived
[root@sunyujun01 ~]# yum install -y keepalived
3.两台机器都安装Nginx，如果yum install -y nginx 提示没有nginx包，需要安装epel后再安装nginx包
[root@sunyujun01 ~]# yum install -y epel-release.noarch
[root@sunyujun01 ~]# yum install -y nginx
4.启动nginx
[root@sunyujun01 conf.d]# systemctl start nginx [root@sunyujun01 conf.d]# ps aux|grep nginx root 5273 0.0 0.2 122892 2100 ? Ss 21:44 0:00 nginx: master process /usr/sbin/nginx nginx 5274 0.3 0.3 123356 3128 ? S 21:44 0:00 nginx: worker process root 5276 0.0 0.0 112664 932 pts/4 S+ 21:44 0:00 grep --color=auto nginx [root@sunyujun01 conf.d]#
5.keepalived+nginx实现web高可用
Keepalived的作用是检测服务器的状态，如果有一台web服务器宕机，或工作出现故障，Keepalived将检测到，并将有故障的服务器从系统中剔除，同时使用其他服务器代替该服务器的工作，当服务器工作正常后Keepalived自动将服务器加入到服务器群中，这些工作全部自动完成，不需要人工干涉，需要人工做的只是修复故障的服务器。
6.配置master上的keepalived配置文件
[root@sunyujun01 keepalived]# > keepalived.conf [root@sunyujun01 keepalived]# vim keepalived.conf
global_defs {
notification_email { （出现问题发邮件的邮箱）
278108678@qq.com
}
notification_email_from 278108678@qq.com （由哪一个邮箱地址发出，可以引用第三方）
smtp_server 127.0.0.1
smtp_connect_timeout 30
router_id LVS_DEVEL
}
vrrp_script chk_nginx { （检测服务是否正常，还记得之前说过的keepalived的check模块吗？）
script "/usr/local/sbin/check_ng.sh" （需要写一个检测脚本，可以自定义）
interval 3 （检测间断3秒）
}
vrrp_instance VI_1 {
state MASTER （定义角色，是master还是backup）
interface ens33 （通过哪一个网卡想backup发送VRRP协议数据包）
virtual_router_id 51 （定义路由器的id，master要和backup保持一致）
priority 100 （权重，master和backup的权重是不一样的）
advert_int 1
authentication { （认证相关的配置）
auth_type PASS （认证的类型是PASS密码）
auth_pass sunyujun （定义密码是多少）
}
virtual_ipaddress { （定义VIP，也就是虚拟IP，这个IP是由keepalived给服务器配置的，服务器靠这个VIP对外提供服务）
192.168.133.200
}
track_script { （加载检查脚本）
chk_nginx
}
}
7.配置keepalived-nginx检查脚本，路径就是在上面配置文件里写的
[root@sunyujun01 keepalived]# vi /usr/local/sbin/check_ng.sh
[root@sunyujun01 keepalived]#
#!/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`
#如果进程为0，则启动nginx，并且再次检测nginx进程数量，
#如果还为0，说明nginx无法启动，此时需要关闭keepalived
if [ $n -eq "0" ]; then
/etc/init.d/nginx start (如果用yum安装的nginx需要修改为 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
8.权限变更，不改权限文件就无法自动加载这个脚本，从而导致不能启动keepalive服务
[root@sunyujun01 ~]# chmod 755 /usr/local/sbin/check_ng.sh [root@sunyujun01 ~]#
9.测试keepalived和nginx服务停止掉自动启动，结果是可以，在这里我们要注意，如果有问题。他的错误日志在/var/log/messages里。要关闭防火墙和selinux，或者更改规则。
[root@sunyujun01 ~]# setenforce 0 [root@sunyujun01 ~]# iptables -F [root@sunyujun01 ~]#
[root@sunyujun01 ~]# systemctl stop firewalld [root@sunyujun01 ~]#
[root@sunyujun01 ~]# systemctl start keepalived [root@sunyujun01 ~]# ps aux|grep keepalived root 46589 0.8 0.1 120704 1476 ? Ss 22:54 0:10 /usr/sbin/keepalived -D root 46590 0.0 0.3 122776 3044 ? S 22:54 0:00 /usr/sbin/keepalived -D root 49699 0.3 0.2 131640 2956 ? S 22:59 0:03 /usr/sbin/keepalived -D root 51578 0.0 0.0 112664 936 pts/1 S+ 23:14 0:00 grep --color=auto keepalived [root@sunyujun01 ~]# ps aux|grep nginx root 50794 0.0 0.2 122892 2104 ? Ss 23:07 0:00 nginx: master process /usr/sbin/nginx nginx 50795 0.0 0.3 123356 3132 ? S 23:07 0:00 nginx: worker process root 51640 0.0 0.0 112664 932 pts/1 R+ 23:14 0:00 grep --color=auto nginx [root@sunyujun01 ~]# systemctl stop nginx [root@sunyujun01 ~]# ps aux|grep nginx root 51748 0.0 0.2 122892 2104 ? Ss 23:15 0:00 nginx: master process /usr/sbin/nginx nginx 51749 0.0 0.3 123356 3132 ? S 23:15 0:00 nginx: worker process root 51754 1.0 0.0 112664 928 pts/1 R+ 23:15 0:00 grep --color=auto nginx [root@sunyujun01 ~]#
10.查看ip 192.168.133.200/32
[root@sunyujun01 ~]# ip addr
1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN qlen 1
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: ens33: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP qlen 1000
link/ether 00:0c:29:33:1b:3e brd ff:ff:ff:ff:ff:ff
inet 192.168.133.88/24 brd 192.168.133.255 scope global ens33
valid_lft forever preferred_lft forever
inet 192.168.133.200/32 scope global ens33
valid_lft forever preferred_lft forever
inet6 fe80::b646:159d:d0ac:4cbe/64 scope link
valid_lft forever preferred_lft forever
[root@sunyujun01 ~]#
11.配置从机backup：（检查主从机子的防火墙和selinux的规则。虚拟环境下我们就关闭它）
12.关闭防火墙
[root@sunyujun02 ~]# iptables -nvL [root@sunyujun02 ~]# iptables -F [root@sunyujun02 ~]# systemctl stop firewalld [root@sunyujun02 ~]# getenforce Enforcing [root@sunyujun02 ~]# setenforce 0 [root@sunyujun02 ~]# getenforce Permissive [root@sunyujun02 ~]#
13.编辑从配置文件
[root@sunyujun02 ~]# > /etc/keepalived/keepalived.conf [root@sunyujun02 ~]# vim /etc/keepalived/keepalived.conf [root@sunyujun02 ~]#
global_defs {
notification_email {
aming@aminglinux.com
}
notification_email_from root@aminglinux.com
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 （这里和主不一样，角色为backup）
interface ens33
virtual_router_id 51 （这里要和主保持一样）
priority 90 （权重要比主低）
advert_int 1
authentication {
auth_type PASS
auth_pass litongyao123 （密码要和主一样）
}
virtual_ipaddress {
192.168.52.99 （虚拟vip要和主一样）
}
track_script {
chk_nginx
}
}
14.编辑监控nginx服务的脚本
[root@sunyujun02 ~]# vim /usr/local/sbin/check_ng.sh
[root@sunyujun02 ~]#
#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`
#如果进程为0，则启动nginx，并且再次检测nginx进程数量，
#如果还为0，说明nginx无法启动，此时需要关闭keepalived
if [ $n -eq "0" ]; then
systemctl start nginx （这里和主的区别，因为我们从机是Yum安装的）
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
15.增加权限，启动keepalived
[root@sunyujun02 ~]# chmod 755 !$ chmod 755 /usr/local/sbin/check_ng.sh [root@sunyujun02 ~]# systemctl start keepalived [root@sunyujun02 ~]# ps aux|grep keep root 2610 0.0 0.1 120704 1400 ? Ss 23:56 0:00 /usr/sbin/keepalived -D root 2611 0.3 0.3 122776 3056 ? S 23:56 0:00 /usr/sbin/keepalived -D root 2612 0.7 0.2 127100 2784 ? S 23:56 0:00 /usr/sbin/keepalived -D root 2683 0.0 0.0 112664 932 pts/1 S+ 23:56 0:00 grep --color=auto keep [root@sunyujun02 ~]#
16.测试主服务器nginx是否通
17.修改从默认页文件title
[root@sunyujun02 ~]# cat /usr/share/nginx/html/index.html
18.从服务器
19.用200服务器访问，发现访问的是主服务器（vip在主上）
20.我们在从上停掉nginx服务试试，发现nginx服务又起来了
[root@sunyujun02 ~]# ps aux|grep nginx root 2637 0.0 0.2 122892 2104 ? Ss 3月05 0:00 nginx: master process /usr/sbin/nginx nginx 2638 0.0 0.3 123356 3572 ? S 3月05 0:00 nginx: worker process root 5534 0.0 0.0 112664 932 pts/1 S+ 00:13 0:00 grep --color=auto nginx [root@sunyujun02 ~]# systemctl stop nginx [root@sunyujun02 ~]# ps aux|grep nginx root 5785 0.0 0.2 122892 2104 ? Ss 00:15 0:00 nginx: master process /usr/sbin/nginx nginx 5786 0.0 0.3 123356 3132 ? S 00:15 0:00 nginx: worker process root 5791 0.0 0.0 112664 932 pts/1 S+ 00:15 0:00 grep --color=auto nginx [root@sunyujun02 ~]#
测试
1.目前vip在master上
[root@sunyujun01 ~]# ip addr
1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN qlen 1
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: ens33: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP qlen 1000
link/ether 00:0c:29:33:1b:3e brd ff:ff:ff:ff:ff:ff
inet 192.168.133.88/24 brd 192.168.133.255 scope global ens33
valid_lft forever preferred_lft forever
inet 192.168.133.200/32 scope global ens33
valid_lft forever preferred_lft forever
inet6 fe80::b646:159d:d0ac:4cbe/64 scope link
valid_lft forever preferred_lft forever
[root@sunyujun01 ~]#
[root@sunyujun02 ~]# ip addr
1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN qlen 1
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: ens33: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP qlen 1000
link/ether 00:0c:29:b2:c6:90 brd ff:ff:ff:ff:ff:ff
inet 192.168.133.66/24 brd 192.168.133.255 scope global ens33
valid_lft forever preferred_lft forever
inet6 fe80::d721:b5f6:8bf1:60d/64 scope link
valid_lft forever preferred_lft forever
[root@sunyujun02 ~]#
2.将主上vrrp出去的包用防火墙封掉（这招测试不好使 哈哈）
[root@sunyujun02 ~]# iptables -I OUTPUT -p vrrp -j DROP
[root@sunyujun02 ~]# iptables -nvL
Chain INPUT (policy ACCEPT 58 packets, 3328 bytes)
pkts bytes target prot opt in out source destination
Chain FORWARD (policy ACCEPT 0 packets, 0 bytes)
pkts bytes target prot opt in out source destination
Chain OUTPUT (policy ACCEPT 21 packets, 1980 bytes)
pkts bytes target prot opt in out source destination
0 0 DROP 112 -- * * 0.0.0.0/0 0.0.0.0/0
[root@sunyujun02 ~]#
3.测试主机宕机场景，直接停掉主机的keepalived服务，发现主200的ip释放了，从上有了200ip
[root@sunyujun01 ~]# systemctl stop keepalived
[root@sunyujun01 ~]# ip addr
1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN qlen 1
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: ens33: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP qlen 1000
link/ether 00:0c:29:33:1b:3e brd ff:ff:ff:ff:ff:ff
inet 192.168.133.88/24 brd 192.168.133.255 scope global ens33
valid_lft forever preferred_lft forever
inet6 fe80::b646:159d:d0ac:4cbe/64 scope link
valid_lft forever preferred_lft forever
[root@sunyujun01 ~]#
[root@sunyujun02 ~]# ip addr
1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN qlen 1
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: ens33: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP qlen 1000
link/ether 00:0c:29:b2:c6:90 brd ff:ff:ff:ff:ff:ff
inet 192.168.133.66/24 brd 192.168.133.255 scope global ens33
valid_lft forever preferred_lft forever
inet 192.168.133.200/32 scope global ens33
valid_lft forever preferred_lft forever
inet6 fe80::d721:b5f6:8bf1:60d/64 scope link
valid_lft forever preferred_lft forever
[root@sunyujun02 ~]#
4.查看从上的日志
[root@sunyujun02 ~]# tail -n 20 /var/log/messages Mar 6 00:15:24 sunyujun02 systemd: Starting The nginx HTTP and reverse proxy server... Mar 6 00:15:24 sunyujun02 nginx: nginx: the configuration file /etc/nginx/nginx.conf syntax is ok Mar 6 00:15:24 sunyujun02 nginx: nginx: configuration file /etc/nginx/nginx.conf test is successful Mar 6 00:15:24 sunyujun02 systemd: Started The nginx HTTP and reverse proxy server. Mar 6 00:21:48 sunyujun02 kernel: perf: interrupt took too long (83390 > 79618), lowering kernel.perf_event_max_sample_rate to 2000 Mar 6 00:33:30 sunyujun02 Keepalived_vrrp[2612]: VRRP_Instance(VI_1) Transition to MASTER STATE Mar 6 00:33:31 sunyujun02 Keepalived_vrrp[2612]: VRRP_Instance(VI_1) Entering MASTER STATE Mar 6 00:33:31 sunyujun02 Keepalived_vrrp[2612]: VRRP_Instance(VI_1) setting protocol VIPs. Mar 6 00:33:31 sunyujun02 Keepalived_vrrp[2612]: Sending gratuitous ARP on ens33 for 192.168.133.200 Mar 6 00:33:31 sunyujun02 Keepalived_vrrp[2612]: VRRP_Instance(VI_1) Sending/queueing gratuitous ARPs on ens33 for 192.168.133.200 Mar 6 00:33:31 sunyujun02 Keepalived_vrrp[2612]: Sending gratuitous ARP on ens33 for 192.168.133.200 Mar 6 00:33:31 sunyujun02 Keepalived_vrrp[2612]: Sending gratuitous ARP on ens33 for 192.168.133.200 Mar 6 00:33:31 sunyujun02 Keepalived_vrrp[2612]: Sending gratuitous ARP on ens33 for 192.168.133.200 Mar 6 00:33:31 sunyujun02 Keepalived_vrrp[2612]: Sending gratuitous ARP on ens33 for 192.168.133.200 Mar 6 00:33:36 sunyujun02 Keepalived_vrrp[2612]: Sending gratuitous ARP on ens33 for 192.168.133.200 Mar 6 00:33:36 sunyujun02 Keepalived_vrrp[2612]: VRRP_Instance(VI_1) Sending/queueing gratuitous ARPs on ens33 for 192.168.133.200 Mar 6 00:33:36 sunyujun02 Keepalived_vrrp[2612]: Sending gratuitous ARP on ens33 for 192.168.133.200 Mar 6 00:33:36 sunyujun02 Keepalived_vrrp[2612]: Sending gratuitous ARP on ens33 for 192.168.133.200 Mar 6 00:33:36 sunyujun02 Keepalived_vrrp[2612]: Sending gratuitous ARP on ens33 for 192.168.133.200 Mar 6 00:33:36 sunyujun02 Keepalived_vrrp[2612]: Sending gratuitous ARP on ens33 for 192.168.133.200 [root@sunyujun02 ~]#
5.访问200ip，发现切换到从上了
6.再次启动从机，发现200 vip又回来了
[root@sunyujun01 ~]# systemctl start keepalived
[root@sunyujun01 ~]# ip addr
1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN qlen 1
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: ens33: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP qlen 1000
link/ether 00:0c:29:33:1b:3e brd ff:ff:ff:ff:ff:ff
inet 192.168.133.88/24 brd 192.168.133.255 scope global ens33
valid_lft forever preferred_lft forever
inet 192.168.133.200/32 scope global ens33
valid_lft forever preferred_lft forever
inet6 fe80::b646:159d:d0ac:4cbe/64 scope link
valid_lft forever preferred_lft forever
[root@sunyujun01 ~]#
7.这就是高可用集群，配置集群时，priority值越大，优先级越高
四、keeplived+MySQL
http://blog.51cto.com/lizhenliang/1362313