nginx+keepalived实现nginx双主高可用的负载均衡
一、前言：在互联网上面，网站为用户提供原始的内容访问，同时为用户提供交互操作。提供稳定可靠的服务，可以给用户带来良好的体验，保证用户的正常访问使用，在网站的可靠性方面，有很多的技术可以来提供，这类技术可以分为：
高可用：保证服务的可靠，稳定，实现故障的屏蔽，避免了单点故障。
高性能：多台服务器连接起来，处理一个复杂的计算问题。
负载均衡：将用户请求引导到后端多台服务器，实现服务器请求的负载。
我们将这类技术称之为集群负载均衡，可以提供负载均衡和高可用的有硬件和软件，软件方面有haproxy，lvs，keepalived，nginx，heartbeat，corosync等等，而这里我们采用的是nginx-keepalived来构建。
Nginx有很强的代理功能，但是一台nginx 就形成了单点，现在使用keepalived来解决这个问题，keepalived可以实现故障转移切换，实现后端的健康检查，前端的高可用，使网站故障记录大大降低，避免了单点故障造成网站无法访问的问题，确保了网站业务的正常运行。
二、Nginx+keepalived有两种配置方案：
2.1、Nginx+keepalived 主从配置
这种方案，使用一个vip地址，前端使用2台机器，一台做主，一台做备，但同时只有一台机器工作，另一台备份机器在主机器不出现故障的时候，永远处于浪费状态，对于服务器不多的网站，该方案不经济实惠，所以本次不予采用。
2.2、Nginx+keepalived 双主配置
这种方案，使用两个vip地址，前端使用2台机器，互为主备，同时有两台机器工作，当其中一台机器出现故障，两台机器的请求转移到一台机器负担，非常适合于当前架构环境，故本次采用此方案对网站进行高可用架构。
三、Nginx+keepalived 主从配置
3.1、Nginx+keepalived 主从配置详情请见http://kling.blog.运维网.com/3320545/1240359
这里不做重点介绍。
四、Ningx+Keepalived 双主配置
4.1、拓扑结构
http://blog.运维网.com/attachment/201307/215431711.png
4.2、测试环境如下：
系统：Ceentos 6.4 64位
前端node1服务器：
DIP: 192.168.122.2
VIP: 192.168.122.22
前端node2服务器：
DIP: 192.168.122.3
VIP：192.168.122.23
后端服务器：
web server01：192.168.122.4
web server02：192.168.122.5
web server03：192.168.122.6
4.3、软件安装
分别在两台前端服务器上安装nginx+keepalived，使用脚本如下：
#!/bin/bash
# author: kuangl
# mail: kuangl@orient-media.com
# description: The installation of Nginx files.
# -------------------------------------------------------- #
## Nginx_install
# -------------------------------------------------------- #
# Nginx installation
#CURRENT_PATH=$(pwd)
for i in $(rpm -q gcc gcc-c++ kernel-devel openssl-devel zlib-devel popt-devel popt-static libnl-devel wget make |grep 'not installed' | awk '{print $2}')
do
yum -y install $i
done
[ -d /root/software ]
[ "$?" != 0 ] && mkdir /root/software
cd /root/software
[ !-e pcre-8.33.tar.gz ] && wget ftp://ftp.csx.cam.ac.uk/pub/software/programming/pcre/pcre-8.33.tar.gz
tar -zxvf pcre-8.33.tar.gz
cd pcre-8.33
./configure
make && make install
echo $? || [ $? != 0] || echo" installation pcrefailed" || exit 1
cd /root/software
[ ! -e nginx-1.2.9.tar.gz ] && wget http://nginx.org/download/nginx-1.2.9.tar.gz
tar -zxvf nginx-1.2.9.tar.gz
cd nginx-1.2.9
./configure--prefix=/usr/local/nginx --with-http_ssl_module --with-http_sub_module --with-http_stub_status_module--with-http_gzip_static_module
make && make install
echo $? || [ $? != 0] || echo" installationnginxfailed" || exit 1
# -------------------------------------------------------- #
## Keepalived_intsall
# -------------------------------------------------------- #
# Keepalived installation
cd /root/softwarae
[ ! -e keepalived-1.2.4.tar.gz ] &&wget http://www.keepalived.org/software/keepalived-1.2.4.tar.gz
tar -zxvf keepalived-1.2.4.tar.gz
cd keepalived-1.2.4
ln -s /usr/src/kernels/$(uname -r) /usr/src/kernels/linux
./configure --prefix=/usr--bindir=/usr/bin--sbindir=/usr/bin--libexecdir=/usr/libexec --localstatedir=/var --libdir=/lib64--infodir=/usr/share/info--sysconfdir=/etc --mandir=/usr/local/share/man --with-kernel-dir=/usr/src/kernels/linux
make && make install
echo $? || [ $? != 0] || print " installation keepalivedfailed" || exit 1
chkconfig --add keepalived
chkconfig --level 345 keepalived on 4.4、在后端服务器上安装apached
后端node4
# yum-y install httpd
# echo "this is 192.168.122.4" > /var/www/htmlindex.html
# service httpd start
# curl192.168.122.4
this is 192.168.122.4 后端node5
# yum-y install httpd
# echo "this is 192.168.122.5" > /var/www/htmlindex.html
# service httpd start
# curl192.168.122.5
this is 192.168.122.5 后端node6
# yum-y install httpd
# echo "this is 192.168.122.6" > /var/www/htmlindex.html
# service httpd start
# curl192.168.122.6
this is 192.168.122.6 4.5、node2、node3上配置nginx
# vim /usr/local/nginx/conf/nginx.conf
upstream web1 ##定义负载均衡组为web1
{
ip_hash;
server 192.168.122.4:80;
server 192.168.122.5:80;
server 192.168.122.6:80;
}
server {
listen 80;
server_namedev.test01.com;
location /
{
root /home/kuangl/;
index index.html index.htm;
proxy_set_header Host $host;
proxy_set_header X-Forwarded-For $remote_addr;
proxy_pass http://web1;
}
} 4.6、在node2上配置keepalived
# vim /etc/keepalived/keepalived.conf
! Configuration File for keepalived
global_defs {
notification_email {
404060945@qq.com
}
notification_email_from root@localhost
smtp_server 127.0.0.1
smtp_connect_timeout 30
router_id LVS_DEVEL
}
vrrp_script chk_haproxy {
script "/etc/keepalived/chk_nginx.sh"
interval 2
weight 2
}
vrrp_instance VI_1 {
state MASTER
interface eth0
virtual_router_id 200
priority 250
advert_int 1
authentication {
auth_type PASS
auth_pass kuanglnginx
}
track_script {
chk_nginx
}
virtual_ipaddress {
192.168.122.22
}
}
vrrp_instance VI_2 {
state BACKUP
interface eth0
virtual_router_id 251
priority 100
advert_int 1
authentication {
auth_type PASS
auth_pass kuangl
}
track_script {
chk_nginx
}
virtual_ipaddress {
192.168.122.23
}
} 4.7、在node3上配置keepalived
! Configuration File for keepalived
global_defs {
notification_email {
404060945@qq.com
}
notification_email_from root@localhost
smtp_server 127.0.0.1
smtp_connect_timeout 30
router_id LVS_DEVEL
}
vrrp_script chk_haproxy {
script "/etc/keepalived/chk_nginx.sh"
interval 2
weight 2
}
vrrp_instance VI_1 {
state BACKUP
interface eth0
virtual_router_id 200
priority 100
advert_int 1
authentication {
auth_type PASS
auth_pass kuanglnginx
}
track_script {
chk_nginx
}
virtual_ipaddress {
192.168.122.22
}
}
vrrp_instance VI_2 {
state MASTER
interface eth0
virtual_router_id 251
priority 250
advert_int 1
authentication {
auth_type PASS
auth_pass kuangl
}
track_script {
chk_nginx
}
virtual_ipaddress {
192.168.122.23
}
} 4.8、在两台双主服务器上添加自动检测脚本
#!/bin/bash
# description:
# 定时查看nginx是否存在，如果不存在则启动nginx
# 如果启动失败，则停止keepalived
status=$(ps -C nginx --no-heading|wc -l)
if [ "${status}" = "0" ]; then
/usr/local/nginx/sbin/nginx
status2=$(ps -C nginx --no-heading|wc -l)
if [ "${status2}" = "0"]; then
/etc/init.d/keepalived stop
fi
fi 4.9、开启nginx、keepalived服务
# service keepalived start
# /usr/local/nginx/sbin/nginx
# service keepalived start
# /usr/local/nginx/sbin/nginx 4.10、用 ip a 查看VIP
http://blog.运维网.com/attachment/201307/222250821.png
http://blog.运维网.com/attachment/201307/222252598.png
4.11、测试访问
$ curl http://192.168.122.22
this is 192.168.122.6
$ curl http://192.168.122.22
this is 192.168.122.4
$ curl http://192.168.122.22
this is 192.168.122.5
$ curl http://192.168.122.23
this is 192.168.122.6
$ curl http://192.168.122.23
this is 192.168.122.4
$ curl http://192.168.122.23
this is 192.168.122.5 五、后端用rsync做数据同步
node5-node6上配置进程模式，以node5为例
# yum -y install rsync
# vim /etc/rsynsd.conf
uid = root
gid = root
use chroot = no
max connections = 5
pid file = /var/run/rsyncd.pid
lock file = /var/run/rsync.lock
log file = /var/log/rsyncd.log
path=/home/kuangl/
comment = update
ignore errors
read only = no
list = no
hosts allow = 192.168.122.0/24
auth users = root
uid = root
gid = root
secrets file = /etc/rsyncd.secrets
# vim /etc/rsyncd.secrets
root:123456
# chmod 0600 /etc/rsyncd.secrets
# ll /etc/rsyncd.secrets
-rw-------. 1 root root 12 Jul 20 19:41 /etc/rsyncd.secrets
# rsync --daemon
# echo "rsync --daemon" >> /etc/rc.local node4上配置命令模式：
# yum -y install rsync
# vim /etc/rsyncd.secrets
123456
# chmod 0600 /etc/rsyncd.secrets
root@node4 kuangl]# rsync -vzrtopg --delete --progress --password-file=/etc/rsyncd.secretsrsync+inotify root@192.168.122.5::web01
sending incremental file list
rsync+inotify/
rsync+inotify/inotify-tools-3.14.tar.gz
358772 100% 1.85MB/s 0:00:00 (xfer#1, to-check=2/4)
rsync+inotify/rsync+inotify_client.sh
617 100% 3.11kB/s 0:00:00 (xfer#2, to-check=1/4)
rsync+inotify/rsync+inotify_server.sh
900 100% 4.03kB/s 0:00:00 (xfer#3, to-check=0/4)
sent 360679 bytesreceived 69 bytes240498.67 bytes/sec
total size is 360289speedup is 1.00 查看结果
# cd /home/kuangl/
# ll
total 8
-rw-r--r--. 1 root root 22 Jul 20 15:16 index.html
drwxr-xr-x. 2 root root 4096 Nov 112012 rsync+inotify
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