1.keepalived介绍
keepalived最初是专为LVS负载均衡软件设计的，用来管理并监控LVS集群系统中各个服务节点的状态，后来又加入了实现高可用的VRRP功能。keepalived除了能够管理LVS软件外，还能支持其他服务的高可用解决方案。
keepalived通过VRRP协议实现高可用功能的。VRRP（Virtual Router Redundancy Protocol）虚拟路由冗余协议。VRRP出现的目的就是为了解决静态路由单点故障问题，它能保证当个别节点宕机时，整个网络可以不间断地运行。
2.keepalived高可用故障转移原理
keepalived高可用服务之间的故障转移，是通过VRRP来实现的。在keepalived服务工作时，主Master节点会不断地向备节点发送（多播的方式）心跳消息，用来告诉备Backup节点自己还活着。
当主节点发生故障时，无法给备节点发送心跳消息，如果备节点无法继续检测到来自主节点的心跳。就会调用自身的接管程序，接管主节点的IP资源和服务。当主节点恢复时，备节点又会释放主节点故障时自身接管的IP资源和服务，恢复到原来的备用角色
3.安装nginx
3.1.主节点（192.168.80.22）
3.1.1.安装编译工具和库文件
yum -y install make zlib zlib-devel gcc-c++ libtool openssl openssl-devel
3.1.2.安装pcre
#进入目录cd /usr/local/develop/anginx#上传安装文件并解压tar -zxvf pcre-8.38.tar.gz#进入安装目录cd pcre-8.38#检查配置./configure#编译、安装make && make install#查看pcre版本pcre-config --version
3.1.3.安装nginx
#进入目录cd /usr/local/develop/anginx#上传安装文件，并解压tar -zxvf nginx-1.8.1.tar.gz#进入安装目录cd nginx-1.8.1#检查配置./configure --prefix=/usr/local/develop/anginx/webserver/nginx --with-http_stub_status_module --with-http_ssl_module --with-pcre=/usr/local/develop/anginx/pcre-8.38#编译安装make && make install#查看nginx版本 /usr/local/develop/anginx/webserver/nginx/sbin/nginx -v--------------------------------------------------------[root@hadoop02 webserver]# /usr/local/develop/anginx/webserver/nginx/sbin/nginx -vnginx version: nginx/1.8.1#配置nginx（检查）/usr/local/develop/anginx/webserver/nginx/sbin/nginx -t#nginx管理命令/usr/local/develop/anginx/webserver/nginx/sbin/nginx # 启动 Nginx/usr/local/develop/anginx/webserver/nginx/sbin/nginx -s stop # 停止 Nginx/usr/local/develop/anginx/webserver/nginx/sbin/nginx -s reload # 重新载入配置文件/usr/local/develop/anginx/webserver/nginx/sbin/nginx -s reopen # 重启 Nginx
3.1.4.nginx基础配置
vi nginx.conf#user nobody;worker_processes 1;#error_log logs/error.log;#error_log logs/error.log notice;#error_log logs/error.log info;pid logs/nginx.pid;events { worker_connections 1024;}http { include mime.types; default_type application/octet-stream; log_format main '$remote_addr - $remote_user [$time_local] "$request" ' '$status $body_bytes_sent "$http_referer" ' '"$http_user_agent" "$http_x_forwarded_for"'; access_log logs/access.log main; sendfile on; #tcp_nopush on; #keepalive_timeout 0; keepalive_timeout 65; #gzip on; #添加tomcat列表，真实应用服务器都放在这 upstream tomcat_pool{ #server tomcat地址:端口号 weight表示权值，权值越大，被分配的几率越大; server 192.168.80.22:8080 weight=4 max_fails=2 fail_timeout=30s; server 192.168.80.22:8081 weight=4 max_fails=2 fail_timeout=30s; } server { listen 80; server_name tomcat_pool; #charset koi8-r; #access_log logs/host.access.log main; location / { #root html; #index index.html index.htm; proxy_pass http://tomcat_pool; #转向tomcat处理 proxy_set_header Host $host; proxy_set_header X-Real-IP $remote_addr; proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for; } #error_page 404 /404.html; # redirect server error pages to the static page /50x.html # error_page 500 502 503 504 /50x.html; location = /50x.html { root html; }}3.2.备节点（192.168.80.21）
说明：安装方式同nginx主节点。
4.安装keepalived
4.1.主节点（192.168.80.22）
#安装keepalivedyum install keepalived -y#启动keepalived服务/etc/init.d/keepalived start-------------------------------------------[root@hadoop02 anginx]# /etc/init.d/keepalived start正在启动 keepalived： [确定][root@hadoop02 anginx]# ps -ef |grep keepalivedroot 15723 1 0 00:59 ? 00:00:00 /usr/sbin/keepalived -Droot 15724 15723 0 00:59 ? 00:00:00 /usr/sbin/keepalived -Droot 15725 15723 0 00:59 ? 00:00:00 /usr/sbin/keepalived -Droot 15731 15622 0 00:59 pts/1 00:00:00 grep keepalived[root@hadoop02 anginx]##设置开机自启动echo "/etc/init.d/keepalived start" >>/etc/rc.local#关闭keepalived服务/etc/init.d/keepalived stop#编辑keepalived配置文件vi /etc/keepalived/keepalived.conf-----------------------------------------------------------! Configuration File for keepalivedglobal_defs { notification_email { acassen@firewall.loc failover@firewall.loc sysadmin@firewall.loc } notification_email_from Alexandre.Cassen@firewall.loc smtp_server 192.168.200.1 smtp_connect_timeout 30 router_id lb01}vrrp_instance VI_1 { state MASTER interface eth1 virtual_router_id 55 priority 150 advert_int 1 authentication { auth_type PASS auth_pass server123 } virtual_ipaddress { 192.168.80.100 dev eth1 label eth1:1 }}关于配置说明：
【router_id】 是路由标识，在一个局域网里面应该是唯一的
【vrrp_instance VI_1】{...}这是一个VRRP实例，里面定义了keepalived的主备状态、接口、优先级、认证和IP信息
【state】 定义了VRRP的角色
【interface】定义使用的接口，这里我的服务器用的网卡都是eth1
【virtual_router_id】是虚拟路由ID标识，一组的keepalived配置中主备都是设置一致
【priority】是优先级，数字越大，优先级越大，
【auth_type】是认证方式
【auth_pass】是认证的密码
【virtual_ipaddress】 ｛...｝定义虚拟IP地址，可以配置多个IP地址，这里我定义为192.168.80.100，绑定了eth1的网络接口，虚拟接口eth1:1
4.2.备节点（192.168.80.21）
#安装keepalivedyum install keepalived -y#启动keepalived服务/etc/init.d/keepalived start-------------------------------------------[root@hadoop02 anginx]# /etc/init.d/keepalived start正在启动 keepalived： [确定][root@hadoop02 anginx]# ps -ef |grep keepalivedroot 15723 1 0 00:59 ? 00:00:00 /usr/sbin/keepalived -Droot 15724 15723 0 00:59 ? 00:00:00 /usr/sbin/keepalived -Droot 15725 15723 0 00:59 ? 00:00:00 /usr/sbin/keepalived -Droot 15731 15622 0 00:59 pts/1 00:00:00 grep keepalived[root@hadoop02 anginx]##设置开机自启动echo "/etc/init.d/keepalived start" >>/etc/rc.local#关闭keepalived服务/etc/init.d/keepalived stop#编辑keepalived配置文件vi /etc/keepalived/keepalived.conf-----------------------------------------------------------------! Configuration File for keepalivedglobal_defs { notification_email { acassen@firewall.loc failover@firewall.loc sysadmin@firewall.loc } notification_email_from Alexandre.Cassen@firewall.loc smtp_server 192.168.200.1 smtp_connect_timeout 30 router_id lb02}vrrp_instance VI_1 { state BACKUP interface eth1 virtual_router_id 55 priority 100 advert_int 1 authentication { auth_type PASS auth_pass server123 } virtual_ipaddress { 192.168.80.100 dev eth1 label eth1:1 }}5.测试
5.1.启动主备节点的keepalived服务
#在节点一执行（192.168.80.22）/etc/init.d/keepalived start-------------------------------------[root@hadoop02 anginx]# ps -ef |grep keepalivedroot 15788 1 0 01:09 ? 00:00:00 /usr/sbin/keepalived -Droot 15790 15788 0 01:09 ? 00:00:00 /usr/sbin/keepalived -Droot 15791 15788 0 01:09 ? 00:00:00 /usr/sbin/keepalived -Droot 15807 15622 0 01:33 pts/1 00:00:00 grep keepalived[root@hadoop02 anginx]##在节点二执行（192.168.80.21）/etc/init.d/keepalived start---------------------------------------[root@hadoop01 ~]# ps -ef |grep keepalivedroot 11542 1 0 01:30 ? 00:00:00 /usr/sbin/keepalived -Droot 11544 1154 0 01:30 ? 00:00:00 /usr/sbin/keepalived -Droot 11545 11542 0 01:30 ? 00:00:00 /usr/sbin/keepalived -Droot 11550 11512 0 01:33 pts/1 00:00:00 grep keepalived[root@hadoop01 ~]#
5.2.通过虚ip访问服务
http://192.168.80.100/session-redis-demo/
5.3.停止主节点keepalived服务
#在节点一执行（192.168.80.22）/etc/init.d/keepalived stop#观察备节点变化ip addr-------------------------------------------[root@hadoop01 ~]# ip addr1: 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 inet6 ::1/128 scope host valid_lft forever preferred_lft forever2: eth1: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP qlen 1000 link/ether 00:50:56:38:e5:46 brd ff:ff:ff:ff:ff:ff inet 192.168.80.21/24 brd 192.168.80.255 scope global eth1 inet 192.168.80.100/32 scope global eth1:1 inet6 fe80::250:56ff:fe38:e546/64 scope link valid_lft forever preferred_lft forever[root@hadoop01 ~]#
5.4.继续通过虚ip访问服务
http://192.168.80.100/session-redis-demo/
6.keepalived+nginx整合
说明：编写nginx守护脚本，如果nginx服务出现故障，则停止当前节点的keepalived服务。自动切换到备用节点。
6.1.编写nginx守护脚本
vi nginx_check.sh--------------------------------------#!/bin/bashwhile truedoif [ $(netstat -tlnp|grep nginx|wc -l) -ne 1 ]then /etc/init.d/keepalived stopfisleep 2done#给脚本授权chmod u+x nginx_check.sh#执行脚本nohup /usr/local/develop/anginx/shell/nginx_check.sh &
6.2.停止主节点nginx服务
#停止主节点nginx服务/usr/local/develop/anginx/webserver/nginx/sbin/nginx -s stop#查找进程[root@hadoop02 ~]# ps -ef |grep nginxroot 15915 1 0 01:51 ? 00:00:00 /bin/bash /usr/local/develop/anginx/shell/nginx_check.shroot 16516 15753 0 01:54 pts/5 00:00:00 grep nginx[root@hadoop02 ~]##观察备用节点变化【服务正常】ip addr--------------------------------------[root@hadoop01 shell]# ip addr1: 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 inet6 ::1/128 scope host valid_lft forever preferred_lft forever2: eth1: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP qlen 1000 link/ether 00:50:56:38:e5:46 brd ff:ff:ff:ff:ff:ff inet 192.168.80.21/24 brd 192.168.80.255 scope global eth1 inet 192.168.80.100/32 scope global eth1:1 inet6 fe80::250:56ff:fe38:e546/64 scope link valid_lft forever preferred_lft forever[root@hadoop01 shell]##再次重新启动主节点nginx和keepalived服务/usr/local/develop/anginx/webserver/nginx/sbin/nginx/etc/init.d/keepalived start