18.1集群介绍 18.2 keepalived介绍18.3/18.4/18.5 用keepalived配置高可用集群
- 18.1 集群介绍- 18.2 keepalived介绍
- 18.3/18.4/18.5 用keepalived配置高可用集群
- 扩展
- heartbeat和keepalived比较 http://blog.csdn.net/yunhua_lee/article/details/9788433
- DRBD工作原理和配置 http://502245466.blog.运维网.com/7559397/1298945
- mysql+keepalived http://lizhenliang.blog.运维网.com/7876557/1362313
# 18.1 集群介绍
- Linux集群概述
- 根据功能划分为两大类：高可用和负载均衡
- 高可用集群通常为两台服务器，一台工作，另外一台作为冗余，当提供服务的机器宕机，冗余将接替继续提供服务 //通常
- 对于大企业来说。可用程度达到99.99%或者 是5个9
- 实现高可用的开源软件有：heartbeat、keepalived //centos6 bug 多，而且很久没有更新了，不建议继续使用；keepalived不仅有高可用还有负载均衡
- 负载均衡集群，需要有一台服务器作为分发器，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F5、Netscaler
# 18.2 keepalived介绍
- 在这里我们使用keepalived来实现高可用集群，因为heartbeat在centos6上有一些问题，影响实验效果
-keepalived通过VRRP（Virtual Router Redundancy Protocl 中文为：虚拟路由器冗余协议）来实现高可用。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。
# 18.3 用keepalived配置高可用集群（上）
- 搭建高可用的前提，是先要有一个工具，然后需要有一个服务去让工具实现高可用，这个实验，就是让nginx作为一个服务，让它成为一个高可用的对象；因为nginx在企业里使用量比较大，所以就使用他来做服务对象
- 环境准备
- master ：192.168.202.131 （已经做过lnmp）
- backup：192.168.202.132（lamp，没有nginx服务）
- 两台机器都安装keepalived
- 执行yum install -y keepalived
- 为了方便做实验
- 检查两台机器的selinux，iptables两个防火墙情况，selinux需要关闭，iptables需要关闭firewalld
- 对backup机器安装nginx服务
- yum install -y nginx
- 准备两台机器aming-01 是131和aming-02 是 132，131作为master，132作为backup
-两台机器都执行yum install -y keepalived
-先是master 安装ke
```
# yum install -y keepalived
已加载插件：fastestmirror
Loading mirror speeds from cached hostfile
* base: mirrors.sohu.com
* epel: mirrors.ustc.edu.cn
已安装:
keepalived.x86_64 0:1.3.5-1.el7
作为依赖被安装:
lm_sensors-libs.x86_64 0:3.4.0-4.20160601gitf9185e5.el7
net-snmp-agent-libs.x86_64 1:5.7.2-28.el7
net-snmp-libs.x86_64 1:5.7.2-28.el7
完毕！
#
| 3.6 kB00:00:00
```
-backup 机器安装keppalived
```
# yum install -y keepalived
已加载插件：fastestmirror
Loading mirror speeds from cached hostfile
已安装:
keepalived.x86_64 0:1.3.5-1.el7
作为依赖被安装:
lm_sensors-libs.x86_64 0:3.4.0-4.20160601gitf9185e5.el7
net-snmp-agent-libs.x86_64 1:5.7.2-28.el7
net-snmp-libs.x86_64 1:5.7.2-28.el7
完毕！
#
```
- 因为之前aming-01 上面做过nginx,所以上面有nginx服务
```
完毕！
# ps aux |grep nginx
root 8680.00.1459921280 ? Ss 21:55 0:00 nginx: master process /usr/local/nginx/sbin/nginx -c /usr/local/nginx/conf/nginx.conf
nobody 8730.00.4484804180 ? S 21:55 0:00 nginx: worker process
nobody 8740.00.3484803924 ? S 21:55 0:00 nginx: worker process
root 24350.00.0 112684 976 pts/0 S+ 22:03 0:00 grep --color=auto nginx
#
```
- 而第二台aming-02 机器上看下有没有nginx,没有就用yum install -y nginx 安装一个
```
# rpm -qa |grep nginx
#
# yum install -y nginx
已安装:
nginx.x86_64 1:1.10.2-2.el7
作为依赖被安装:
gd.x86_64 0:2.0.35-26.el7
gperftools-libs.x86_64 0:2.4-8.el7
libXpm.x86_64 0:3.5.12-1.el7
libunwind.x86_64 2:1.2-2.el7
libxslt.x86_64 0:1.1.28-5.el7
nginx-all-modules.noarch 1:1.10.2-2.el7
nginx-filesystem.noarch 1:1.10.2-2.el7
nginx-mod-http-geoip.x86_64 1:1.10.2-2.el7
nginx-mod-http-image-filter.x86_64 1:1.10.2-2.el7
nginx-mod-http-perl.x86_64 1:1.10.2-2.el7
nginx-mod-http-xslt-filter.x86_64 1:1.10.2-2.el7
nginx-mod-mail.x86_64 1:1.10.2-2.el7
nginx-mod-stream.x86_64 1:1.10.2-2.el7
完毕！
#
```
- 在这有俩个nginx 一个是源码包安装的nginx ，一个是yum 安装的nginx ，
- 下面更改配置文件
- master机器配置，服务工具准备好以后，就配置keepalived ，默认的配置文件路径在
- 先把里面内容清空，有个快捷键 >!$添加如下配置，
```
# ls /etc/keepalived/keepalived.conf
/etc/keepalived/keepalived.conf
# vim /etc/keepalived/keepalived.conf
# > !$
> /etc/keepalived/keepalived.conf
#
```
- 添加如下配置
```
# !vim
vim /etc/keepalived/keepalived.conf
global_defs {
notification_email { //邮件
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" //检查服务是否正常，通过脚本实现，检查服务健康状态
interval 3 //检查时间
}
vrrp_instance VI_1 {
state MASTER //定义master相关
interface ens33 //通过那个网站使用vrrp协议，配置时，需注意你的网卡配置文件是否是哪个。因为系统ens并不是固定的。
virtual_router_id 51 //定义路由器ID ，配置的时候和从机器一致
priority 100 //权重，
advert_int 1
authentication { //认证相关信息
auth_type PASS
auth_pass aminglinux>com
}
virtual_ipaddress { //定义一个公有IP（VIP）
192.168.188.100 //更改为192.168.202.100
}
track_script {
chk_nginx
}
}
-- 插入 -- 30,2 底端
# vim /etc/keepalived/keepalived.conf
```
- 配置文件编辑完了之后还需要定义check脚本
- 定义一个check的脚本
```
# vim /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`
#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
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
~
~
~
~
-- 插入 -- 15,3 全部
# vim /usr/local/sbin/check_ng.sh
#
```
# 18.4 用keepalived配置高可用集群（中）
- 写完脚本之后，还需要对它做一个权限更改，如果没有权限加载这个脚本的话，它就没有办法启动keepalived服务。
```
# chmod 755 /usr/local/sbin/check_ng.sh
#
```
- 启动keepalived 服务
```
# systemctl start keepalived
#
# ps aux |grep keep
root 2498 12.90.1 1207201468 ? Ss 22:35 0:07 /usr/sbin/keepalived -D
root 24990.00.2 1207202752 ? S 22:35 0:00 /usr/sbin/keepalived -D
root 196050.00.0 112680 980 pts/0 R+ 22:36 0:00 grep --color=auto keep
# ps aux |grep nginx
root 8680.00.1459921280 ? Ss 21:55 0:00 nginx: master process /usr/local/nginx/sbin/nginx -c /usr/local/nginx/conf/nginx.conf
nobody 8730.00.4484804180 ? S 21:55 0:00 nginx: worker process
nobody 8740.00.3484803924 ? S 21:55 0:00 nginx: worker process
root 301040.00.0 112680 980 pts/0 R+ 22:37 0:00 grep --color=auto nginx
#
```
- 先停止nginx 看看是否会自动启动,结果是会的，
```
# /etc/init.d/nginx stop
Stopping nginx (via systemctl): [确定]
#
# /etc/init.d/nginx stop
Stopping nginx (via systemctl): [确定]
# ps aux |grep nginx
root 1153140.00.1459921296 ? Ss 22:50 0:00 nginx: master process /usr/local/nginx/sbin/nginx -c /usr/local/nginx/conf/nginx.conf
nobody 1153180.00.3484803940 ? S 22:50 0:00 nginx: worker process
nobody 1153190.00.3484803940 ? S 22:50 0:00 nginx: worker process
root 1153450.00.0 112680 980 pts/0 S+ 22:51 0:00 grep --color=auto nginx
#
# date
2017年 11月 08日 星期三 22:51:34 CST
#
```
- keepalived,它的日志在哪里
```
# less /var/log/messages
Nov8 22:48:27 aming-01 Keepalived: VRRP child process(102776) died: Respawning
Nov8 22:48:27 aming-01 Keepalived: VRRP child process(102777) died: Respawning
Nov8 22:48:27 aming-01 Keepalived: VRRP child process(102778) died: Respawning
Nov8 22:48:27 aming-01 Keepalived: VRRP child process(102779) died: Respawning
Nov8 22:48:27 aming-01 rsyslogd-2177: imjournal: begin to drop messages due to rate-limiting
(END)
```
- 来看下它的IP地址,要用ip add ，用ifconfig 看不到的
```
# ip add
1: lo: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:mtu 1500 qdisc pfifo_fast state UP qlen 1000
link/ether 00:0c:29:2e:28:f2 brd ff:ff:ff:ff:ff:ff
inet 192.168.202.131/24 brd 192.168.202.255 scope global ens33
valid_lft forever preferred_lft forever
inet 192.168.202.100/32 scope global ens33
valid_lft forever preferred_lft forever
inet 192.168.202.151/24 brd 192.168.202.255 scope global secondary ens33:0
valid_lft forever preferred_lft forever
inet6 fe80::ecdd:28b7:612b:cb7/64 scope link
valid_lft forever preferred_lft forever
3: ens37:mtu 1500 qdisc pfifo_fast state UP qlen 1000
link/ether 00:0c:29:2e:28:fc brd ff:ff:ff:ff:ff:ff
inet 192.168.202.134/24 brd 192.168.202.255 scope global dynamic ens37
valid_lft 1259sec preferred_lft 1259sec
inet6 fe80::707c:946e:3252:cf7f/64 scope link
valid_lft forever preferred_lft forever
#
```
-使用ifconfig
```
# ifconfig
ens33: flags=4163mtu 1500
inet 192.168.202.131netmask 255.255.255.0broadcast 192.168.202.255
inet6 fe80::ecdd:28b7:612b:cb7prefixlen 64scopeid 0x20
ether 00:0c:29:2e:28:f2txqueuelen 1000(Ethernet)
RX packets 7277bytes 6239399 (5.9 MiB)
RX errors 0dropped 0overruns 0frame 0
TX packets 4120bytes 413974 (404.2 KiB)
TX errors 0dropped 0 overruns 0carrier 0collisions 0
ens33:0: flags=4163mtu 1500
inet 192.168.202.151netmask 255.255.255.0broadcast 192.168.202.255
ether 00:0c:29:2e:28:f2txqueuelen 1000(Ethernet)
ens37: flags=4163mtu 1500
inet 192.168.202.134netmask 255.255.255.0broadcast 192.168.202.255
inet6 fe80::707c:946e:3252:cf7fprefixlen 64scopeid 0x20
ether 00:0c:29:2e:28:fctxqueuelen 1000(Ethernet)
RX packets 86bytes 9064 (8.8 KiB)
RX errors 0dropped 0overruns 0frame 0
TX packets 20bytes 3096 (3.0 KiB)
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 1(Local Loopback)
RX packets 10bytes 876 (876.0 B)
RX errors 0dropped 0overruns 0frame 0
TX packets 10bytes 876 (876.0 B)
TX errors 0dropped 0 overruns 0carrier 0collisions 0
#
```
- 配置从之前，查看下主服务器 有没有防火墙, 以及selinux，从 也是一样
```
# iptables -nvL
Chain INPUT (policy ACCEPT 0 packets, 0 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 0 packets, 0 bytes)
pkts bytes target prot opt in out source destination
#
# getenforce
Permissive
#
```
- 检查下从服务器,如果有停止掉
```
# systemctl stop firewalld
# iptables -nvL
Chain INPUT (policy ACCEPT 0 packets, 0 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 0 packets, 0 bytes)
pkts bytes target prot opt in out source destination
#
# getenforce
Enforcing
# setenforce 0
# getenforce
Permissive
#
```
- 也需要配置下keepalived,先需要情况里面的原始的配置文件内容，再添加如下内容
```
# > /etc/keepalived/keepalived.conf
# vi !$
vi /etc/keepalived/keepalived.conf
# vi /etc/keepalived/keepalived.conf
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
interface ens33
virtual_router_id 51
priority 90
advert_int 1
authentication {
auth_type PASS
auth_pass aminglinux>com
}
virtual_ipaddress {
192.168.202.100 这个网段需要和主一样
}
track_script {
chk_nginx
}
}
:wq
# vi /etc/keepalived/keepalived.conf
#
```
- 脚本也需要去写下
```
# vim /usr/local/sbin/check_ng.sh
#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
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
~
~
~
~
:wq
# vim /usr/local/sbin/check_ng.sh
#
```
- 也需要改变权限，不然就启动不了 keepalived
```
# chmod 755 /usr/local/sbin/check_ng.sh
#
```
- 启动keepalived
```
# ps aux |grep keep
root 25350.00.1 1207201404 ? Ss 23:16 0:00 /usr/sbin/keepalived -D
root 25360.00.3 1274603344 ? S 23:16 0:00 /usr/sbin/keepalived -D
root 25370.00.3 1315883024 ? S 23:16 0:00 /usr/sbin/keepalived -D
root 26010.00.0 112680 980 pts/0 S+ 23:16 0:00 grep --color=auto keep
#
```
- 主从都启动了 keepalived，现在俩边 主从 都有 nginx，那你怎么去区分这个nginx？
- 先来看下主的ip
```
# ifconfig
ens33: flags=4163mtu 1500
inet 192.168.202.131netmask 255.255.255.0broadcast 192.168.202.255
inet6 fe80::ecdd:28b7:612b:cb7prefixlen 64scopeid 0x20
ether 00:0c:29:2e:28:f2txqueuelen 1000(Ethernet)
RX packets 7410bytes 6251067 (5.9 MiB)
RX errors 0dropped 0overruns 0frame 0
TX packets 5672bytes 512782 (500.7 KiB)
TX errors 0dropped 0 overruns 0carrier 0collisions 0
ens33:0: flags=4163mtu 1500
inet 192.168.202.151netmask 255.255.255.0broadcast 192.168.202.255
ether 00:0c:29:2e:28:f2txqueuelen 1000(Ethernet)
ens37: flags=4163mtu 1500
inet 192.168.202.134netmask 255.255.255.0broadcast 192.168.202.255
inet6 fe80::707c:946e:3252:cf7fprefixlen 64scopeid 0x20
ether 00:0c:29:2e:28:fctxqueuelen 1000(Ethernet)
RX packets 108bytes 11608 (11.3 KiB)
RX errors 0dropped 0overruns 0frame 0
TX packets 24bytes 3900 (3.8 KiB)
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 1(Local Loopback)
RX packets 10bytes 876 (876.0 B)
RX errors 0dropped 0overruns 0frame 0
TX packets 10bytes 876 (876.0 B)
TX errors 0dropped 0 overruns 0carrier 0collisions 0
#
```
- 先去windows 上用浏览器访问下
!(http://oqxf7c508.bkt.clouddn.com/blog/20171108/232640129.png?imageslim)
- 这台机器的默认配置文件
```
# cat /usr/local/nginx/conf/vhost/
aaa.com.conf ld.conf proxy.conf ssl.conf test.com.conf
# cat /usr/local/nginx/conf/vhost/aaa.com.conf
server
{
listen 80 default_server;
server_name aaa.com;
index index.html index.htm index.php;
root /data/wwwroot/default;
location ~ \.php$
{
include fastcgi_params;
fastcgi_pass unix:/tmp/aming.sock;
fastcgi_index index.php;
fastcgi_param SCRIPT_FILENAME /data/wwwroot/default$fastcgi_script_name;
}
}
#
# vim !$
vim /data/wwwroot/default/index.html
master master. This is the default site.
~
~
:wq
```
-!(http://oqxf7c508.bkt.clouddn.com/blog/20171108/233113698.png?imageslim)
-关于backup ，从服务器上面，它的nginx 是yum安装的
```
# vim /usr/share/nginx/html/index.html
# cat !$
cat /usr/share/nginx/html/index.html
backup backup.
#
```
!(http://oqxf7c508.bkt.clouddn.com/blog/20171108/233606639.png?imageslim)
!(http://oqxf7c508.bkt.clouddn.com/blog/20171109/000815047.png?imageslim)
- 查看下nginx服务,这个是我们手动起来的，可以停掉试下
```
# ps aux |grep nginx
root 25610.00.2 1227922084 ? Ss 23:16 0:00 nginx: master process /usr/sbin/nginx
nginx 25620.00.3 1232243576 ? S 23:16 0:00 nginx: worker process
root 69850.00.0 112680 976 pts/0 S+ 23:43 0:00 grep --color=auto nginx
#
# systemctl stop nginx
# !ps
ps aux |grep nginx
root 71550.00.2 1227922084 ? Ss 23:44 0:00 nginx: master process /usr/sbin/nginx
nginx 71560.00.3 1232243128 ? S 23:44 0:00 nginx: worker process
root 71610.00.0 112680 980 pts/0 S+ 23:44 0:00 grep --color=auto nginx
#
```
- 因为开启了keepalived 服务，所以即使停掉nginx服务，它也会自动加载起来的
# 18.5 用keepalived配置高可用集群（下）
- 先确定好两台机器上nginx差异，比如可以通过curl -I 来查看nginx版本
-测试1：关闭master上的nginx服务
我们之前都已经测试过了，关闭还是会继续运行，因为加了那个脚本 开启了keepalived服务
-测试2：在master上增加iptabls规则
-iptables -I OUTPUT -p vrrp -j DROP
-测试3：关闭master上的keepalived服务
-测试4：启动master上的keepalived服务
-这个vip 是在主上 master 上
```
# ip add
1: lo: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:mtu 1500 qdisc pfifo_fast state UP qlen 1000
link/ether 00:0c:29:2e:28:f2 brd ff:ff:ff:ff:ff:ff
inet 192.168.202.131/24 brd 192.168.202.255 scope global ens33
valid_lft forever preferred_lft forever
inet 192.168.202.100/32 scope global ens33
valid_lft forever preferred_lft forever
inet 192.168.202.151/24 brd 192.168.202.255 scope global secondary ens33:0
valid_lft forever preferred_lft forever
inet6 fe80::ecdd:28b7:612b:cb7/64 scope link
valid_lft forever preferred_lft forever
3: ens37:mtu 1500 qdisc pfifo_fast state UP qlen 1000
link/ether 00:0c:29:2e:28:fc brd ff:ff:ff:ff:ff:ff
inet 192.168.202.134/24 brd 192.168.202.255 scope global dynamic ens37
valid_lft 1369sec preferred_lft 1369sec
inet6 fe80::707c:946e:3252:cf7f/64 scope link
valid_lft forever preferred_lft forever
#
```
- backup上是没有的
```
# ip add
1: lo: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:mtu 1500 qdisc pfifo_fast state UP qlen 1000
link/ether 00:0c:29:58:33:e6 brd ff:ff:ff:ff:ff:ff
inet 192.168.202.132/24 brd 192.168.202.255 scope global ens33
valid_lft forever preferred_lft forever
inet 192.168.202.152/24 brd 192.168.202.255 scope global secondary ens33:0
valid_lft forever preferred_lft forever
inet6 fe80::4500:6d42:8612:4e53/64 scope link
valid_lft forever preferred_lft forever
inet6 fe80::ecdd:28b7:612b:cb7/64 scope link tentative dadfailed
valid_lft forever preferred_lft forever
#
```
- 咱们在主上加一个防火墙规则
- 把主上的vrrp进去的包给封掉 iptables -I OUTPUT -p vrrp -j DROP
```
# iptables -I OUTPUT -p vrrp -j DROP
#
# iptables -nvL
Chain INPUT (policy ACCEPT 109 packets, 5868 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 32 packets, 2968 bytes)
pkts bytes target prot opt in out source destination
742960 DROP 112--* * 0.0.0.0/0 0.0.0.0/0
#
```
- 看下日志
```
# tail /var/log/messages
Nov9 00:21:58 aming-01 Keepalived_vrrp: Sending gratuitous ARP on ens33 for 192.168.202.100
Nov9 00:21:58 aming-01 Keepalived_vrrp: Sending gratuitous ARP on ens33 for 192.168.202.100
Nov9 00:21:58 aming-01 Keepalived_vrrp: Sending gratuitous ARP on ens33 for 192.168.202.100
Nov9 00:21:58 aming-01 Keepalived_vrrp: VRRP_Instance(VI_1) Received advert with lower priority 90, ours 100, forcing new election
Nov9 00:21:58 aming-01 Keepalived_vrrp: Sending gratuitous ARP on ens33 for 192.168.202.100
Nov9 00:21:58 aming-01 Keepalived_vrrp: VRRP_Instance(VI_1) Sending/queueing gratuitous ARPs on ens33 for 192.168.202.100
Nov9 00:21:58 aming-01 Keepalived_vrrp: Sending gratuitous ARP on ens33 for 192.168.202.100
Nov9 00:21:58 aming-01 Keepalived_vrrp: Sending gratuitous ARP on ens33 for 192.168.202.100
Nov9 00:21:58 aming-01 Keepalived_vrrp: Sending gratuitous ARP on ens33 for 192.168.202.100
Nov9 00:21:58 aming-01 Keepalived_vrrp: Sending gratuitous ARP on ens33 for 192.168.202.100
#
```
- 再看下从
```
# less /var/log/messages
Nov7 22:01:01 aming-02 systemd: Started Session 4 of user root.
Nov7 22:01:01 aming-02 systemd: Starting Session 4 of user root.
Nov7 23:01:01 aming-02 systemd: Started Session 5 of user root.
Nov7 23:01:01 aming-02 systemd: Starting Session 5 of user root.
Nov7 23:49:27 aming-02 kernel: hrtimer: interrupt took 6003226 ns
Nov8 00:01:01 aming-02 systemd: Started Session 6 of user root.
Nov8 00:01:01 aming-02 systemd: Starting Session 6 of user root.
Nov8 00:33:47 aming-02 rsyslogd: exiting on signal 15.
Nov8 21:55:29 aming-02 rsyslogd: start
Nov8 21:55:09 aming-02 kernel: Initializing cgroup subsys cpuset
Nov8 21:55:09 aming-02 kernel: Initializing cgroup subsys cpu
Nov8 21:55:09 aming-02 kernel: Initializing cgroup subsys cpuacct
Nov8 21:55:09 aming-02 kernel: Linux version 3.10.0-514.el7.x86_64 (builder@kbuilder.dev.centos.org) (gcc version 4.8.5 20150623 (Red Hat 4.8.5-11) (GCC) ) #1 SMP Tue Nov 22 16:42:41 UTC 2016
Nov8 21:55:09 aming-02 kernel: Command line: BOOT_IMAGE=/vmlinuz-3.10.0-514.el7.x86_64 root=UUID=9a2a0d05-a7ab-4948-bbd2-77b2b7d5f565 ro crashkernel=auto rhgb quiet LANG=zh_CN.UTF-8
Nov8 21:55:09 aming-02 kernel: Disabled fast string operations
Nov8 21:55:09 aming-02 kernel: e820: BIOS-provided physical RAM map:
Nov8 21:55:09 aming-02 kernel: BIOS-e820: usable
Nov8 21:55:09 aming-02 kernel: BIOS-e820: reserved
Nov8 21:55:09 aming-02 kernel: BIOS-e820: reserved
/var/log/messages
```
- !(http://oqxf7c508.bkt.clouddn.com/blog/20171109/002641992.png?imageslim)
- 这个也照常可以访问，说明直接封这里的ip是不能直接达到目的的
- 先把这个iptables 规则恢复
```
# iptables -F
#
```
- 那怎么样模仿现实中宕机的环境，
- 只能暂停keepalived服务试下
```
# systemctl stop keepalived
# ip add
1: lo: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:mtu 1500 qdisc pfifo_fast state UP qlen 1000
link/ether 00:0c:29:2e:28:f2 brd ff:ff:ff:ff:ff:ff
inet 192.168.202.131/24 brd 192.168.202.255 scope global ens33
valid_lft forever preferred_lft forever
inet 192.168.202.151/24 brd 192.168.202.255 scope global secondary ens33:0
valid_lft forever preferred_lft forever
inet6 fe80::ecdd:28b7:612b:cb7/64 scope link
valid_lft forever preferred_lft forever
3: ens37:mtu 1500 qdisc pfifo_fast state UP qlen 1000
link/ether 00:0c:29:2e:28:fc brd ff:ff:ff:ff:ff:ff
inet 192.168.202.134/24 brd 192.168.202.255 scope global dynamic ens37
valid_lft 1452sec preferred_lft 1452sec
inet6 fe80::707c:946e:3252:cf7f/64 scope link
valid_lft forever preferred_lft forever
#
```
- 再去从服务器看看
```
# ip add
1: lo: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:mtu 1500 qdisc pfifo_fast state UP qlen 1000
link/ether 00:0c:29:58:33:e6 brd ff:ff:ff:ff:ff:ff
inet 192.168.202.132/24 brd 192.168.202.255 scope global ens33
valid_lft forever preferred_lft forever
inet 192.168.202.100/32 scope global ens33
valid_lft forever preferred_lft forever
inet 192.168.202.152/24 brd 192.168.202.255 scope global secondary ens33:0
valid_lft forever preferred_lft forever
inet6 fe80::4500:6d42:8612:4e53/64 scope link
valid_lft forever preferred_lft forever
inet6 fe80::ecdd:28b7:612b:cb7/64 scope link tentative dadfailed
valid_lft forever preferred_lft forever
#
# tail /var/log/messages
Nov9 00:29:54 aming-02 Keepalived_vrrp: Sending gratuitous ARP on ens33 for 192.168.202.100
Nov9 00:29:54 aming-02 Keepalived_vrrp: Sending gratuitous ARP on ens33 for 192.168.202.100
Nov9 00:29:54 aming-02 Keepalived_vrrp: Sending gratuitous ARP on ens33 for 192.168.202.100
Nov9 00:29:54 aming-02 Keepalived_vrrp: Sending gratuitous ARP on ens33 for 192.168.202.100
Nov9 00:29:59 aming-02 Keepalived_vrrp: Sending gratuitous ARP on ens33 for 192.168.202.100
Nov9 00:29:59 aming-02 Keepalived_vrrp: VRRP_Instance(VI_1) Sending/queueing gratuitous ARPs on ens33 for 192.168.202.100
Nov9 00:29:59 aming-02 Keepalived_vrrp: Sending gratuitous ARP on ens33 for 192.168.202.100
Nov9 00:29:59 aming-02 Keepalived_vrrp: Sending gratuitous ARP on ens33 for 192.168.202.100
Nov9 00:29:59 aming-02 Keepalived_vrrp: Sending gratuitous ARP on ens33 for 192.168.202.100
Nov9 00:29:59 aming-02 Keepalived_vrrp: Sending gratuitous ARP on ens33 for 192.168.202.100
#
```
- 访问日志可以看到，ip被增加了，现在来访问下web
- !(http://oqxf7c508.bkt.clouddn.com/blog/20171109/003125547.png?imageslim)
- 可以看到发生了改变，说明vip 已经到了从机器上
- 那再把这个keepalived服务 开启
```
# systemctl start keepalived
# ip add
1: lo: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:mtu 1500 qdisc pfifo_fast state UP qlen 1000
link/ether 00:0c:29:2e:28:f2 brd ff:ff:ff:ff:ff:ff
inet 192.168.202.131/24 brd 192.168.202.255 scope global ens33
valid_lft forever preferred_lft forever
inet 192.168.202.100/32 scope global ens33
valid_lft forever preferred_lft forever
inet 192.168.202.151/24 brd 192.168.202.255 scope global secondary ens33:0
valid_lft forever preferred_lft forever
inet6 fe80::ecdd:28b7:612b:cb7/64 scope link
valid_lft forever preferred_lft forever
3: ens37:mtu 1500 qdisc pfifo_fast state UP qlen 1000
link/ether 00:0c:29:2e:28:fc brd ff:ff:ff:ff:ff:ff
inet 192.168.202.134/24 brd 192.168.202.255 scope global dynamic ens37
valid_lft 1276sec preferred_lft 1276sec
inet6 fe80::707c:946e:3252:cf7f/64 scope link
valid_lft forever preferred_lft forever
#
```
- 可以看到马上就能变回来，再看下web访问
- !(http://oqxf7c508.bkt.clouddn.com/blog/20171109/003318786.png?imageslim)
- 看下从上面的日志, 显示 removing protocol VIPs
```
# tail /var/log/messages
Nov9 00:29:59 aming-02 Keepalived_vrrp: VRRP_Instance(VI_1) Sending/queueing gratuitous ARPs on ens33 for 192.168.202.100
Nov9 00:29:59 aming-02 Keepalived_vrrp: Sending gratuitous ARP on ens33 for 192.168.202.100
Nov9 00:29:59 aming-02 Keepalived_vrrp: Sending gratuitous ARP on ens33 for 192.168.202.100
Nov9 00:29:59 aming-02 Keepalived_vrrp: Sending gratuitous ARP on ens33 for 192.168.202.100
Nov9 00:29:59 aming-02 Keepalived_vrrp: Sending gratuitous ARP on ens33 for 192.168.202.100
Nov9 00:32:17 aming-02 chronyd: Selected source 120.25.108.11
Nov9 00:32:17 aming-02 chronyd: System clock wrong by -1.225785 seconds, adjustment started
Nov9 00:32:51 aming-02 Keepalived_vrrp: VRRP_Instance(VI_1) Received advert with higher priority 100, ours 90
Nov9 00:32:51 aming-02 Keepalived_vrrp: VRRP_Instance(VI_1) Entering BACKUP STATE
Nov9 00:32:51 aming-02 Keepalived_vrrp: VRRP_Instance(VI_1) removing protocol VIPs.
#
```
- 因为主机器宕机，从机器很快的就加入了vip地址，这个时候访问vip地址的时候，看到的页面是
- 从机器上的默认索引页，证明整个实验成功
- 这就是高可用的一个集群，通常会用俩台机器，有的企业为了保险，可能会用2-3台backup
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