nginx+keepalived 高可用方案

=>软件以及环境介绍
	操作系统 centos6.5
	nginx 1.5.7
	keepalived 1.2.9
	挂载安装光盘里面的文件到系统中
	虚拟机IP 192.168.1.106   192.168.1.108
	

=>开启网络端口(防止后续端口不能用问题)
	A、vi /etc/selinux/config
	B、设置 SELINUX=disabled 保存
	C、执行  setenforce 0
	
=>设置IPTABLES
	A、vi /etc/sysconfig/iptables
	B、-A INPUT -m state --state NEW -m tcp -p tcp --dport 80:9000 -j ACCEPT
	C、/etc/init.d/iptables restart
	
=>安装nginx（以192.168.1.106为例）
	(root 用户)
	1、 tar xvzf  nginx-1.5.7.tar.gz
	查找openssl是否安装的路径
	whereis openssl
	openssl: /usr/bin/openssl /usr/lib/openssl /usr/include/openssl /usr/share/man/man1/openssl.1ssl.gz

	cd nginx-1.5.7
	./configure --prefix=/opt/nginx --with-openssl=/usr/include/openssl/ --sbin-path=/opt/nginx/nginx

	报如下错误：
	./configure: error: the HTTP rewrite module requires the PCRE library.
	You can either disable the module by using --without-http_rewrite_module
	option, or install the PCRE library into the system, or build the PCRE library
	statically from the source with nginx by using --with-pcre=<path> option.
		make
		make install
	2、 安装pcre-8.30
	rpm -ivh pcre-7.8-6.el6.x86_64.rpm 
	rpm -ivh pcre-devel-7.8-6.el6.x86_64.rpm
	(最新下载地址   ftp://ftp.csx.cam.ac.uk/pub/software/programming/pcre/放到
	tar xvzf  pcre-8.30.tar.gz ，光盘中Packages中有)
	3、 重新安装Nginx
	4、 cd /opt/nginx 
	5、运行nginx ./nginx
	6、
	6、 在浏览器中输入http://127.0.0.1
	显示welcome to nginx 安装成功

=>安装keepalived
	前言
	最近因业务扩展，需要将当前的apache 转为nginx(web), 再在web前端放置nginx(负载均衡)。同时结合keepalived 对前端nginx实现HA。
	nginx进程基于于Master+Slave(worker)多进程模型，自 身具有非常稳定的子进程管理功能。在Master进程分配模式下，Master进程永远不进行业务处理，
	只是进行任务分发，从而达到Master进程的存 活高可靠性，Slave(worker)进程所有的业务信号都 由主进程发出，Slave(worker)进程所有的超时任务都会
	被Master中止，属于非阻塞式任务模型。
	Keepalived是Linux下面实现VRRP 备份路由的高可靠性运行件。基于Keepalived设计的服务模式能够真正做到主服务器和备份服务器故障时IP瞬间无缝交接。
	二者结合，可以构架出比较稳定的软件lb方案。

	A、tar xvzf keepalived-1.2.9.tar.gz
	B、cd keepalived-1.2.9
	C、./configure	
		Keepalived configuration
		------------------------
		Keepalived version       : 1.2.9
		Compiler                 : gcc
		Compiler flags           : -g -O2
		Extra Lib                : -lssl -lcrypto -lcrypt 
		Use IPVS Framework       : Yes
		IPVS sync daemon support : Yes
		IPVS use libnl           : No
		Use VRRP Framework       : Yes
		Use VRRP VMAC            : Yes
		SNMP support             : No
		SHA1 support             : No
		Use Debug flags          : No
	D、例如出现下面情况，将不支持lvs！
		Keepalived configuration
		------------------------
		Keepalived version       : 1.1.15
		Compiler                 : gcc
		Compiler flags           : -g -O2
		Extra Lib                : -lpopt -lssl -lcrypto
		Use IPVS Framework       : No
		IPVS sync daemon support : No
		Use VRRP Framework       : Yes
		Use LinkWatch            : No
		Use Debug flags          : No
		解决办法，指定kernel目录：
		./configure --with-kernel-dir=/usr/src/kernels/2.6.32-431.el6.x86_64/
		./configure --with-kernel-dir=/usr/src/kernels/2.6.18-164.el5-i686/（rhel5.4_32平台）
	E、make && make install

=>nginx+keepalived高可用性负载均衡
	前言
	最近因业务扩展，需要将当前的apache 转为nginx(web), 再在web前端放置nginx(负载均衡)。同时结合keepalived 对前端nginx实现HA。
	nginx进程基于于Master+Slave(worker)多进程模型，自 身具有非常稳定的子进程管理功能。在Master进程分配模式下，Master进程永远不进行业务处理，
	只是进行任务分发，从而达到Master进程的存 活高可靠性，Slave(worker)进程所有的业务信号都 由主进程发出，Slave(worker)进程所有的超时任务都会
	被Master中止，属于非阻塞式任务模型。
	Keepalived是Linux下面实现VRRP 备份路由的高可靠性运行件。基于Keepalived设计的服务模式能够真正做到主服务器和备份服务器故障时IP瞬间无缝交接。
	二者结合，可以构架出比较稳定的软件lb方案。

	nginx master（主nginx服务器） 192.168.1.106

	nginx backup（备nginx服务器） 192.168.1.108

	vip（被切换的虚拟IP） 192.168.1.107

	A、创建目录 mkdir /etc/keepalived
		cd /etc/keepalived
		编写nginx脚本（当nginx死掉的时候，尝试启动nginx，如果尝试失败，
			则杀死keepalived进程，备份服务器上面发现主服务器keepalived进程死掉了之后，就会启动nginx,切换虚拟IP
			）
			vi nginx_pid.sh
			#!/bin/bash
			A=`ps -C nginx --no-header |wc -l`
			if [ $A -eq 0 ];then
				/opt/nginx/nginx
				sleep 3
				if [ `ps -C nginx --no-header |wc -l` -eq 0 ];then
					 killall keepalived
				fi
			fi

		保存到/etc/keepalived下面
		设置脚本权限 chmod +x /etc/keepalived/nginx_pid.sh

	B、keeaplived 配置(默认keepalived启动的时候加载的路径/etc/keepalived/keepalived.conf)
		vi /etc/keepalived/keepalived.conf
		主机（192.168.1.106）的配置文件
			 global_defs {
		     	    notification_email {
			      user@example.com
			    }

			   notification_email_from mail@example.org
			   smtp_server 192.168.200.1
			   smtp_connect_timeout 30
                           router_id LVS_DEVEL
                        }
                        vrrp_script chk_nginx {
                                script "/etc/keepalived/nginx_pid.sh"
                                interval 2
                                weight 2
                        }
                        vrrp_instance VI_1 {
                            state MASTER
                            interface eth0
                            virtual_router_id 51
                            priority 101  #备份机的权重要低于101
                            advert_int 1
                            authentication {
                                auth_type PASS
                                auth_pass 1111
                            }
                            virtual_ipaddress {
                                192.168.1.107
                            }

                            track_script {
                                chk_nginx
                            }
                        }
		备份机（192.168.1.108）配置文件
		 	global_defs {
				
                           router_id LVS_DEVEL
                        }
                        vrrp_script chk_nginx {
                                script "/etc/keepalived/nginx_pid.sh"
                                interval 2
                                weight 2
                        }
                        vrrp_instance VI_1 {
                            state BACKUP
                            interface eth0
                            virtual_router_id 51
                            priority 100  #备份机的权重要低于主机
                            advert_int 1
                            authentication {
                                auth_type PASS
                                auth_pass 1111
                            }
                            virtual_ipaddress {
                                192.168.1.107
                            }

                            track_script {
                                chk_nginx
                            }
                        }

                                     
	C、 cp /usr/local/sbin/keepalived /usr/sbin/
	    cp /usr/local/etc/sysconfig/keepalived /etc/sysconfig/
	    cp /usr/local/etc/rc.d/init.d/keepalived /etc/init.d/

	D、启动keepalived
		keepalived
		或者指定配置文件启动 keepalived –f /usr/local/etc/keepalived/keepalived.conf 
	E、查看启动日志tail -f /var/log/message
		[root@localhost keepalived]# tail -f /var/log/messages 
		Dec 14 11:51:33 localhost Keepalived_healthcheckers[9221]: Registering Kernel netlink command channel
		Dec 14 11:51:33 localhost Keepalived_healthcheckers[9221]: Opening file '/etc/keepalived/keepalived.conf'.
		Dec 14 11:51:33 localhost Keepalived_vrrp[9222]: Registering gratuitous ARP shared channel
		Dec 14 11:51:33 localhost Keepalived_vrrp[9222]: Opening file '/etc/keepalived/keepalived.conf'.
		Dec 14 11:51:33 localhost Keepalived_vrrp[9222]: Configuration is using : 64084 Bytes
		Dec 14 11:51:33 localhost Keepalived_vrrp[9222]: Using LinkWatch kernel netlink reflector...
		Dec 14 11:51:33 localhost Keepalived_healthcheckers[9221]: Configuration is using : 5933 Bytes
		Dec 14 11:51:33 localhost Keepalived_healthcheckers[9221]: Using LinkWatch kernel netlink reflector...
		Dec 14 11:51:34 localhost Keepalived_vrrp[9222]: VRRP_Instance(VI_1) Transition to MASTER STATE
		Dec 14 11:51:35 localhost Keepalived_vrrp[9222]: VRRP_Instance(VI_1) Entering MASTER STATE
	F、查看 虚拟IP  
	   ip a

=>测试	
	A、访问192.168.1.107 
		查看两台nginx访问日志发现是在192.168.1.106虚拟机上面
		tail -f /opt/nginx/logs/access.log
	A、杀掉192.168.1.106 上面的nginx 
		/opt/nginx/nginx -s stop
		你会发现192.168.1.106上面的nginx自动beikeepalived重启了
	C、杀掉192.168.1.106上面的keepalived
	 killall keepalived	
	 再访问192.168.1.107
	 查看两台nginx的日志 
	 发现访问到192.168.1.108 虚拟机上面了
	D、启动192.168.1.106上面的keepalived 又会切换回来
	
=>vritualbox拷贝虚拟机(由于图像界面clone选项导致uuid重复,故采用 VBoxManage )
	先要把虚拟机关掉，然后执行克隆