摘要：
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，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实现高可用的开源软件有：hea... 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，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
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
各有个优势
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，虚拟路由冗余协议）来实现高可用。
1、它是实现路由高可用的一种通信协议，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。
2、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。
3、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。
用Keepalived配置高可用集群
生产环境中，很多企业把Nginx作为负载均衡器来用，它的重要性很高，一旦宕机会导致整个站点不能访问，所以有必要再准备一台备用Nginx，Keepalived用在这种场景下非常合适。
1.准备工作
准备两台机器
master：172.11.1.3 安装keepaliver+nginx backup：172.11.1.6 安装keepaliver+nginx vip：172.11.1.10
VIP的英文名字是“Virtual IP",即“虚拟IP",也有人把它叫作“浮动IP”，因为这个IP是由Keepalived给服务器配置上的，服务器靠这个VIP对外提供服务，当master机器宕机，VIP被分配到backup上，这样用户看来是无感知的。
master和backup都安装keepalived+nginx
yum install -y keepalived 如nginx服务没有则yum安装[ root@ahao02 ~]# yum install -y epel-release [root@ahao02 ~]# yum install nginx -y
2.编辑master机器的keepalived配置文件
# > /etc/keepalived/keepalived.conf //清空配置文件
#vi /etc/keepalived/keepalived.conf
#定义报警人邮箱
global_defs {notification_email {
ahao@ahaoyw.com
}
#定义发件地址
notification_email_from root@aminglinux.com
smtp_server 127.0.0.1
smtp_connect_timeout 30
router_id LVS_DEVEL}
#chk_nginx为自定义名字，后面会用到
vrrp_script chk_nginx {
#自定义脚本，该脚本为监控nginx服务的脚本script "/usr/local/sbin/check_ng.sh"interval 3}
#定义master还是backupvrrp_instance VI_1 {state MASTER
#针对哪个网卡监听vipinterface ens33#定义路由idvirtual_router_id 51#定义权重priority 100
advert_int 1
authentication {
#定义密码，可以自定义auth_type PASS
auth_pass ahaoyw>com}定义VIP公用的
virtual_ipaddress {172.11.1.10}
#加载脚本track_script {chk_nginx}}3.编辑master机器的监控脚本
//脚本名字是自定义的，与keepalived配置文件要一致#!/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 keepalivedif [ $n -eq "0" ]; then/etc/init.d/nginx start n2=`ps -C nginx --no-heading|wc -l`if [ $n2 -eq "0" ]; thenecho "$d nginx down,keepalived will stop" >> /var/log/check_ng.log systemctl stop keepalivedfifi
3.1、设置脚本权限
# chmod 755 /usr/local/sbin/check_ng.sh //需要给它权限，否则无法被keepalived调用加载
3.2、启动服务
systemctl start keepalived //启动master上的keepalived，如果nginx服务没有启动，它会自动拉起来，并监听VIP //启动master上的keepalived，如果nginx服务没有启动，它会自动拉起来，并监听VIP [root@ahao-01 ~]# ps aux |grep keeproot 24268 0.0 0.1 118588 1384 ? Ss 23:31 0:00 /usr/sbin/keepalived -D root 24269 0.0 0.3 127452 3288 ? S 23:31 0:00 /usr/sbin/keepalived -D root 24270 0.0 0.2 127392 2832 ? S 23:31 0:00 /usr/sbin/keepalived -D root 24290 0.0 0.0 112680 976 pts/0 R+ 23:31 0:00 grep --color=auto keep
#日志存放地址：/var/log/messages
4.两台机器都查看防火墙及SElinux是否开启，开启需要关闭
[root@ahao01 ~]# setenforce 0 //临时关闭SELinux//开机关闭SELinux编辑/etc/selinux/config文件，将SELINUX的值设置为disabled [root@ahao01 ~]# getenforce //查看SElinux是否关闭Disabled [root@ahao01 ~]# systemctl stop firewalld.service //关闭防火墙 [root@ahao01 ~]# iptables -nvL //查看防火墙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
5.编辑backup的Keepalived配置文件
[root@ahao02 ~]# > /etc/keepalived/keepalived.conf
[root@ahao02 ~]# vim /etc/keepalived/keepalived.conf增加如下配置内容:
global_defs {
notification_email {
ahao@ahaoyw.com }
notification_email_from root@ahaoyw.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 ahaoyw>com }
virtual_ipaddress {
172.11.1.10 //这个跟master一样 }
track_script {
chk_nginx }}注意：其中state和priority有变化6.编辑backup机器的监控脚本
编辑增加如下配置内容：#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 keepalivedif [ $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 fifi [root@ahao02 ~]# chmod 755 /usr/local/sbin/check_ng.sh //更改权限 [root@ahao02 ~]# systemctl start keepalived //启动服务 [root@ahao02 ~]# ps aux |grep keeproot 16039 0.0 0.1 120720 1400 ? Rs 19:51 0:00 /usr/sbin/keepalived -D root 16040 0.0 0.3 122792 3104 ? S 19:51 0:00 /usr/sbin/keepalived -D root 16041 0.1 0.2 127116 2656 ? S 19:51 0:00 /usr/sbin/keepalived -D root 16059 0.0 0.0 112676 976 pts/0 S+ 19:51 0:00 grep --color=auto keep[root@ahao02 ~]# ps aux |grep nginxroot 15771 0.0 0.0 46308 948 ? Ss 16:56 0:00 nginx: master process /usr/sbin/nginx -c /etc/nginx/nginx.conf nginx 15772 0.0 0.2 46692 2148 ? S 16:56 0:00 nginx: worker process root 16077 0.0 0.0 112676 972 pts/0 S+ 19:51 0:00 grep --color=auto nginx
7.测试高可用
确定好两台机器上nginx差异,通过curl -I 来查看nginx版本
##master机器 [root@ahao01 ~]# curl 172.11.1.3 -IHTTP/1.1 200 OK Server: nginx/1.12.1 Date: Tue, 22 May 2018 02:00:05 GMT Content-Type: text/html Content-Length: 612 Last-Modified: Tue, 22 May 2018 01:49:47 GMT Connection: keep-alive ETag: "5b03773b-264"Accept-Ranges: bytes ##backup机器 [root@ahao02 ~]# curl 172.11.1.6 -IHTTP/1.1 200 OK Server: nginx/1.12.2 Date: Tue, 22 May 2018 02:01:15 GMT Content-Type: text/html Content-Length: 3700 Last-Modified: Tue, 06 Mar 2018 09:26:21 GMT Connection: keep-alive ETag: "5a9e5ebd-e74"Accept-Ranges: bytes
测试1：关闭master上的nginx服务
1、停止master的nginx服务 [root@ahao01 ~]# /etc/init.d/nginxd stop稍等个片刻后，在来检测端口发现端口有被启动了 [root@ahao01 ~]# ps aux |grep nginx root 2607 0.0 0.0 112724 964 pts/0 R+ 14:34 0:00 grep --color=auto nginx [root@ahao01 ~]# ps aux |grep nginx root 2628 0.0 0.0 20540 612 ? Ss 14:34 0:00 nginx: master process /usr/local/nginx/sbin/nginx -c /usr/local/nginx/conf/nginx.conf nobody 2632 0.0 0.1 20980 1064 ? S 14:34 0:00 nginx: worker process root 2634 0.0 0.0 112724 964 pts/0 S+ 14:34 0:00 grep --color=auto nginx
测试2：在master上增加iptabls规则限制vrrp发包
[root@ahao01 ~]# iptables -I OUTPUT -p vrrp -j DROP //把主上VRRP协议出去的包封掉 [root@ahao01 ~]# iptables -nvL //查看防火墙Chain INPUT (policy ACCEPT 22 packets, 1608 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 15 packets, 1428 bytes) pkts bytes target prot opt in out source destination 19 760 DROP 112 -- * * 0.0.0.0/0 0.0.0.0/0 在backup上查看 [root@ahao01 ~]# ip add 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:cd:ad:61 brd ff:ff:ff:ff:ff:ff inet 172.11.1.6/24 brd 172.11.1.255 scope global ens33 valid_lft forever preferred_lft forever inet 172.11.1.10/32 scope global ens33 valid_lft forever preferred_lft forever inet6 fe80::fe20:400d:b43b:9db7/64 scope link valid_lft forever preferred_lft forever [root@ahao02 ~]# tail /var/log/messages May 22 14:46:49 ahao02 systemd: Started The nginx HTTP and reverse proxy server. May 22 14:47:20 ahao02 systemd: Stopping The nginx HTTP and reverse proxy server... May 22 14:47:20 ahao02 systemd: Stopped The nginx HTTP and reverse proxy server. May 22 14:47:30 ahao02 systemd: Starting The nginx HTTP and reverse proxy server... May 22 14:47:30 ahao02 nginx: nginx: the configuration file /etc/nginx/nginx.conf syntax is ok May 22 14:47:30 ahao02 nginx: nginx: configuration file /etc/nginx/nginx.conf test is successful May 22 14:47:30 ahao02 systemd: Failed to read PID from file /run/nginx.pid: Invalid argument May 22 14:47:30 ahao02 systemd: Started The nginx HTTP and reverse proxy server. May 22 15:01:01 ahao02 systemd: Started Session 8 of user root. May 22 15:01:01 ahao02 systemd: Starting Session 8 of user root.
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[root@ahao01 ~]# iptables -F //在master恢复防火墙 [root@ahao01 ~]# tail /var/log/messagesMay 22 14:45:18 ahao01 Keepalived[2244]: Stopping May 22 14:45:18 ahao01 systemd: Stopping LVS and VRRP High Availability Monitor... May 22 14:45:18 ahao01 Keepalived_vrrp[2246]: VRRP_Instance(VI_1) sent 0 priority May 22 14:45:18 ahao01 Keepalived_vrrp[2246]: VRRP_Instance(VI_1) removing protocol VIPs. May 22 14:45:18 ahao01 Keepalived_healthcheckers[2245]: Stopped May 22 14:45:19 ahao01 Keepalived_vrrp[2246]: Stopped May 22 14:45:19 ahao01 Keepalived[2244]: Stopped Keepalived v1.3.5 (03/19,2017), git commit v1.3.5-6-g6fa32f2 May 22 14:45:19 ahao01 systemd: Stopped LVS and VRRP High Availability Monitor. May 22 15:01:01 ahao01 systemd: Started Session 3 of user root. May 22 15:01:01 ahao01 systemd: Starting Session 3 of user root.
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