经过以前做完的产品，受前公司几位前辈技术大拿指点，来自己动手实现并总结一下web端的负载解决方法，高手请略过，个人认知有限，请各位指正错误。
下面是结构图：
我的系统环境是Fedora22(适用readhat,centos)
2台物理机分别用于nginx的master和slaver
192.168.10.244
192.168.10.245
0.准备keepalived,nginx,
可以使用wget下载，也可直接去官网下载，这里我下载的版本是：
keepalived-1.2.19.tar.gz (官方下载地址：http://www.keepalived.org/download.html)
nginx-1.9.3.tar.gz (官方下载地址：http://nginx.org/en/download.html)
压缩包授权
chmod keepalived-1.2..tar.gz
chmod nginx-1.9..tar.gz
解压到相应的目录(随便哪个目录，注意这里不是安装目录，我的是/home/ops/tools/)
tar -zxvf keepalived-1.2..tar.gz
tar -zxvf nginx-1.9..tar.gz
1.安装nginx（nginx依赖其它组件，因此需要先安装依赖，官网文档有详细说明）
进入解压后的nginx所在目录：
cd /usr/local/nginx/nginx-1.9.
检查nginx依赖是否安装：
./configure
出现：
checking for C compiler ... not found ./configure : error: C compiler cc is not found
缺少gcc依赖，安装gcc,执行：
dnf -y install gcc
安装完之后再次检查依赖是否齐全：
./configure
出现：
./configure: error :the HTTP rewrite module requires the PCRE library . 后面巴拉巴拉一片
缺少pcre库依赖，安装pcre-devel
dnf -y install pcre-devel
安装完之后再次检查依赖是否齐全命令同上，出现：
./configure: error: the HTTP gzip module requires the zlib library.
You can either disable the module by using --without-http_gzip_module
option, or install the zlib library into the system, or build the zlib library
statically from the source with nginx by using --with-zlib=<path> option.
依次同上，再次安装zlib
dnf -y install zlib-devel
安装完,出现如下类似日志，说明nginx依赖安装成功(http://nginx.org/en/docs/configure.html，最新版本的doc文档上没有提到openssl可以不安装，原因不明，烦请知道的大哥告知一声)。
Configuration summary
+ using system PCRE library
+ OpenSSL library is not used
+ using builtin md5 code
+ sha1 library is not found
+ using system zlib library
nginx path prefix: "/usr/local/nginx"
nginx binary file: "/usr/local/nginx/sbin/nginx"
nginx configuration prefix: "/usr/local/nginx/conf"
nginx configuration file: "/usr/local/nginx/conf/nginx.conf"
nginx pid file: "/usr/local/nginx/logs/nginx.pid"
nginx error log file: "/usr/local/nginx/logs/error.log"
nginx http access log file: "/usr/local/nginx/logs/access.log"
nginx http client request body temporary files: "client_body_temp"
nginx http proxy temporary files: "proxy_temp"
nginx http fastcgi temporary files: "fastcgi_temp"
nginx http uwsgi temporary files: "uwsgi_temp"
nginx http scgi temporary files: "scgi_temp"
OK，此时开始编译安装nginx，配置nginx的安装目录，个人习惯将其所有配置都安装在固定的目录下/usr/local/nginx,目录不存在时，安装中自动创建(官网上根据职责安装到不同的目录),分别执行:
./configure --prefix=/usr/local/nginx/
make && make install
configure的作用不知道的烦请自行查阅，安装完成后出现如下类似界面，说明安装成功，此时可以删除下载和解压的nginx源码包了.
我习惯用源码安装
官网推荐源码安装的例子有这么一段:
./configure
--sbin-path=/usr/local/nginx/nginx
--conf-path=/usr/local/nginx/nginx.conf
--pid-path=/usr/local/nginx/nginx.pid
--with-http_ssl_module
--with-pcre=../pcre-8.40
--with-zlib=../zlib-1.2.
所以我就直接拷贝下来,进入源码解压目录执行:
./configure --sbin-path=/usr/local/nginx/nginx --conf-path=/usr/local/nginx/nginx-1.13./nginx.conf --pid-path=/usr/local/nginx/nginx-1.13./nginx.pid --with-http_ssl_module --with-pcre=../pcre-8.40 --with-zlib=../zlib-1.2. --with-openssl=../openssl
进入nginx安装目录，启动nginx测试一下
cd /usr/local/nginx/sbin
./nginx
查看一下进程:
ps -aux | grep nginx
外部浏览器访问出现如下图，表示nginx启动成功
2.安装keepalived
进入解压后的keepalived的目录，同上先检查依赖是否安装
./configure
若出现:
configure: error:
!!! OpenSSL is not properly installed on your system. !!!!!! Can not include OpenSSL headers files. !!!
安装openssl依赖
dnf -y install openssl-devel
再次检查依赖，若出现如下类似说明依赖安装成功
Keepalived configuration
------------------------
Keepalived version : 1.2.
Compiler : gcc
Compiler flags : -g -O2
Extra Lib : -lssl -lcrypto -lcrypt
Use IPVS Framework : Yes
IPVS sync daemon support : Yes
IPVS use libnl : No
fwmark socket support : Yes
Use VRRP Framework : Yes
Use VRRP VMAC : Yes
SNMP support : No
SHA1 support : No
Use Debug flags : No
OK,此时可以正式安装keepalived了，个人安装在/usr/local/keepalived目录
./configure --prefix=/usr/local/keepalived
make && make install
安装成功后进入安装后的目录，检测
cd /usr/local/keepalived/sbin
./keepalived
查看是否启动成功
ps -aux | grep keepalived
另一台机器以同样的方式安装nginx和keepalived
3.配置keepalived和nginx（测试时可以先略过这一步）
进入目录/usr/local/keepalived/sbin/,查看keepalived的启动配置参数
cd /usr/local/keepalived/sbin
./keepalived --help
注：该help参数可以在/usr/local/keepalived/etc/sysconfig/keepalived这个文件中查看）
keepalived启动时默认加载/etc/keepalived/keepalived.conf。此处个人遇到很大的坑，以为keepalived跟nginx一样安装到指定目录后会从这个安装后的目录去加载配置文件，没想到启动后日志一直停留在start...使用 ip a 查看虚拟IP也绑定不了。最后没办法只好在etc下新建keepalived目录，把keepalived.conf拷过去才解决。
mkdir /etc/keepalived
cp /usr/local/keepalived/etc/keepalived/keepalived.conf /etc/keepalived
我的2台nginx配置文件nginx.conf部分配置片段如下:(这里我在118的机器上起了4个tomcat实例，nginx不配负载方式默认是轮询),用作测试
# blentle add
upstream www.test.dev {
server 192.168.10.118:;
server 192.168.10.118:;
server 192.168.10.118:;
server 192.168.10.118:;
} server {
listen ;
server_name 127.0.0.1;
location / {
index index.php index.html index.jsp;
proxy_pass http://www.test.dev;
proxy_set_header X-Real-IP $remote_addr;
proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
} }
4.配置keepalived，实现nginx负载
（1）主从(master-slaver)
所谓主从即master的nginx正常提供服务时，永远轮不到slaver的nginx来提供服务。只有当master挂掉时，slaver的nginx才接管虚拟IP，提供正常服务。貌似有点浪费服务器。
（a）配置master(192.168.10.244)
vi /etc/keepalived/keepalived.conf
将以下内容替换keepalived.conf里面的内容
! Configuration File for keepalived
global_defs {
notification_email {
admin@milipp.com
}
notification_email_from dev@milipp.com
smtp_server mail.milipp.com
smtp_connect_timeout
router_id LVS_DEVEL
}
11 vrrp_script chk_nginx {
12 script "/home/ops/scripts/monitor-nginx.sh" #这个即使监控nginx宕机的脚本实现自动切换
13 interval 2
14 weight -5
15 fall 3
16 rise 2
17 }
vrrp_instance VI_1 {
state MASTER
interface eth0 #主nginx ip对应的网卡名,使用ifconfig查看
mcast_src_ip 192.168.10.244 #主nginx的ip
virtual_router_id #虚拟路由id，主从必须一致
priority #优先级，主比从大
advert_int
authentication {
auth_type PASS
auth_pass
}
virtual_ipaddress {
192.168.10.246 #虚拟ip,主从必须一致，可以陪配置多个
}
track_script {
chk_nginx #上面配的监控nginx的脚本
}
}
(b).配置slaver(192.168.10.245)
vi /etc/keepalived/keepalived.conf
将以下内容替换keepalived.conf里面的内容
! Configuration File for keepalived
global_defs {
notification_email {
renhuan@milipp.com
}
notification_email_from xuyongming@milipp.com
smtp_server mail.example.com
smtp_connect_timeout
router_id LVS_DEVEL
}
vrrp_script chk_nginx {
script "/home/ops/scripts/monitor_nginx.sh"
interval
weight -
fall
rise
}
vrrp_instance VI_1 {
state BACKUP
interface enp3s0
mcast_src_ip 192.168.10.245
virtual_router_id
priority
advert_int
authentication {
auth_type PASS
auth_pass
}
virtual_ipaddress {
192.168.10.246
}
track_script {
chk_nginx
}
}
监控脚本/home/ops/scripts/monitor_nginx.sh的内容:
#!/bin/bash
counter=$(ps -C nginx --no-heading|wc -l)
if [ "${counter}" = "" ]; then
/usr/local/nginx/sbin/nginx
sleep
counter=$(ps -C nginx --no-heading|wc -l)
if [ "${counter}" = "" ]; then
/usr/local/keepalived/sbin/keepalived stop
fi
fi
即当nginx挂掉后，停掉keepalived
测试:
分别启动两台nginx和两台keepalived，使用虚拟ip 192.168.10.246访问。
在244上执行：
ip a
得到结果：
虚拟ip绑定到244上，以同样的方式查看245，结果245没有绑定虚拟ip
此时停掉245的keepalived或者nginx,使用虚拟ip 246访问，没有问题，查看绑定情况,发现245绑定了虚拟ip。至此测试成功。
（2）主主(master master)
TODO: