Linux巩固记录（9） keepalived+nginx搭建高可用负载分发环境

环境准备（继续服用hadoop节点）

slave1 192.168.2.201（CentOs 7）

slave2 192.168.2.202（CentOs 7）

slave1 和 slave2 上都安装nginx+keepalived

web 192.168.2.100 再iis上启动了9011/9012/9013三个端口的web应用

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1.首先在slave节点上安装nginx（slave节点安装相同，需要修改的地方我会注释出来）或者通过 rpm -Uvh http://nginx.org/packages/centos/7/noarch/RPMS/nginx-release-centos-7-0.el7.ngx.noarch.rpm 后yum -y install nginx进行安装，免除编译

#安装编译nginx需要的相关依赖
yum -y install pcre-devel openssl-devel perl-ExtUtils-Embed

cd /usr/local/src

#获取nginx
wget http://nginx.org/download/nginx-1.5.3.tar.gz


#解压
tar -zxvf nginx-1.5.3.tar.gz

cd nginx-1.5.3

#创建www组下www用户
useradd -s /sbin/nologin -M www

#配置路径及参数（注意最后那部分标红色的参数）
./configure --prefix=/usr/local/nginx --user=www --group=www --with-http_ssl_module --with-http_gzip_static_module --without-http_uwsgi_module --without-http_scgi_module --without-http_upstream_ip_hash_module --with-http_perl_module --with-pcre --with-ld-opt="-Wl,-E" 

#编译及安装 
make && make install

#测试用默认配置文件是否成功
[root@slave1 nginx-1.5.3]# /usr/local/nginx/sbin/nginx -t
nginx: the configuration file /usr/local/nginx/conf/nginx.conf syntax is ok
nginx: configuration file /usr/local/nginx/conf/nginx.conf test is successful

#修改nginx配置文件
vi /usr/local/nginx/conf/nginx.conf

user www www;
worker_processes 8;
error_log logs/error.log;
pid logs/nginx.pid;

events {
    worker_connections 1024;
}

http {
    include mime.types;
    default_type application/octet-stream;
    sendfile on;
    tcp_nopush on;
    keepalive_timeout 65;
    gzip on;

    upstream web_server_pool {
        #ip_hash; #如果需要保持session一致，需要开启这个选项，可以保证同一台机器每次访问都分配到同一服务器
        server 192.168.2.100:9011 weight=4 max_fails=2 fail_timeout=30s;
        server 192.168.2.100:9012 weight=4 max_fails=2 fail_timeout=30s;
        server 192.168.2.100:9013 weight=4 max_fails=2 fail_timeout=30s;
    }

    server {
        listen 80;
        server_name slave1; # node2 改为slave2 或者ip地址
        location / {
            root html;
            index index.html index.htm;
            proxy_pass http://web_server_pool;
            proxy_set_header Host $host;
            proxy_set_header X-Real-IP $remote_addr;
            proxy_set_header X-Forwarded-For $remote_addr;
        }
        error_page 500 502 503 504 /50x.html;
        location = /50x.html {
            root html;
        }
    }
}

#启动nginx
/usr/local/nginx/sbin/nginx #默认会加载其上级目录conf中的nginx.conf

#如果加载其他路径的配置文件按照如下方式进行
/usr/local/nginx/sbin/nginx -c /usr/local/nginx/conf/nginx.conf

#检查运行情况
[root@slave1 nginx-1.5.3]# ps -ef | grep nginx
root       5112      1  0 21:34 ?        00:00:00 nginx: master process /usr/local/nginx/sbin/nginx -c /usr/local/nginx/conf/nginx.conf
www        5113   5112  0 21:34 ?        00:00:00 nginx: worker process
www        5114   5112  0 21:34 ?        00:00:00 nginx: worker process
www        5115   5112  0 21:34 ?        00:00:00 nginx: worker process
www        5116   5112  0 21:34 ?        00:00:00 nginx: worker process
www        5117   5112  0 21:34 ?        00:00:00 nginx: worker process
www        5118   5112  0 21:34 ?        00:00:00 nginx: worker process
www        5119   5112  0 21:34 ?        00:00:00 nginx: worker process
www        5120   5112  0 21:34 ?        00:00:00 nginx: worker process
root       5317   2537  0 21:53 pts/0    00:00:00 grep --color=auto nginx

输入slave1的IP地址 http://192.168.2.201/ 进行访问，结果如下（默认为轮训，请多次刷新浏览器）

salve2方法类似，注意配置文件中红色部分，修改为salve2即可

===========================================================================================================================================================================================================

2.安装keepalived

yum -y install keepalived

顺便提下：最初我采用和nginx一样的下载源码编译方式安装，一直没通过，甚至还修改了Makefile也不行，C语言丢了好多年了，就没继续折腾了

#编辑配置文件
vi /etc/keepalived/keepalived.conf

global_defs {
    notification_email { #指定keepalived在发生事情的时候，发送邮件告知，可以有多个地址，每行一个。
        changw.xiao@qq.com
    }
    notification_email_from changw.xiao@qq.com #指定发件人
    smtp_server smtp.qq.com #发送email的smtp地址
    smtp_connect_timeout 30 #超时时间
    router_id NODEA #运行keepalived的机器的一个标识,多个节点标识可以相同，也可以不同
    vrrp_skip_check_adv_addr 
    vrrp_strict       #严格执行VRRP协议规范，此模式不支持节点单播
    vrrp_garp_interval 0
    vrrp_gna_interval 0
}

vrrp_script chk_http_port {
    script "/usr/local/chk_nginx_pid.sh"  #这用于keepalived检测nginx是否还在运行
    interval 2
    weight 2
}

vrrp_instance VI_1 {
    state MASTER   #主节点用master，其他都用backup
    interface ens33    #网卡名称
    virtual_router_id 50 #所有节点参数要一致
    priority 100   #权重，值越大，优先分派
    advert_int 1
    authentication {
        auth_type PASS
        auth_pass 1111
    }
    track_script {
        chk_http_port
    }
    virtual_ipaddress {
        192.168.2.199/24    #虚拟ip，暴露给调用方使用的，调用方就通过这个ip获取服务，不会关心nginx和具体服务地址
    }
}

同时我把backup节点配置信息也一并贴出来

global_defs {
   router_id NODEB
}

vrrp_script chk_http_port {
    script "/usr/local/chk_nginx_pid.sh"
    interval 2
    weight 2
}

vrrp_instance VI_1 {
    state BACKUP
    interface ens33
    virtual_router_id 50
    priority 90 
    advert_int 1
    authentication {
        auth_type PASS
        auth_pass 1111
    }
   track_script {
       chk_http_port
   }

    virtual_ipaddress {
        192.168.2.199/24
    }
}

backup节点配置文件中少了邮件通知配置，不过邮件通知配置是错误的，没生效，具体日后研究了贴配置

配置文件中有一个shell脚本用于检测nginx是否启动

vi /usr/local/chk_nginx_pid.sh

#!/bin/bash
if [ "$(ps -ef | grep "nginx: master process"| grep -v grep )" == "" ]
then 
    systemclt start nginx.service  #尝试重启（通过编译方式安装的貌似不生效）
    sleep 5   
  if [ "$(ps -ef | grep "nginx: master process"| grep -v grep )" == "" ] 
  then  
    killall keepalived  #关掉keepalived，以便进行切换VIP指向
  fi 
fi

记得修改shell权限

chmod 775 /usr/local/chk_nginx_pid.sh

启动keepalived

keepalived -D -f /etc/keepalived/keepalived.conf

[root@slave1 nginx-1.5.3]# ps -ef |grep keepalived
root       5635      1  0 22:20 ?        00:00:00 keepalived -D -f /etc/keepalived/keepalived.conf
root       5636   5635  0 22:20 ?        00:00:00 keepalived -D -f /etc/keepalived/keepalived.conf
root       5637   5635  0 22:20 ?        00:00:00 keepalived -D -f /etc/keepalived/keepalived.conf
root       5972   5637  0 22:22 ?        00:00:00 keepalived -D -f /etc/keepalived/keepalived.conf
root       5980   2537  0 22:22 pts/0    00:00:00 grep --color=auto keepalived
[root@slave1 nginx-1.5.3]#

同样的方式在salve2上配置，注意配置文件红色标记的地方

在浏览器输入虚拟ip 192.168.2.199 进行访问

此时通过ip addr 命令进行ip查询

slave1

slave2

keepalived + nginx就是为了实现高可用，如果任意一台nginx或者keepalived挂掉之后，只要环境中还有一台机器正在执行，用户都应该能对应用进行访问

下面模拟环境发生故障

根据keepalived里面配置的检测nginx的脚本，如果检测到nginx挂掉后，应该会尝试重启，如果重启不成功，就会关掉该服务器上对应的keepalived，这样就会进行VIP切换

1.由于现在slave1为VIP指向地址，现在关闭掉slave1上的nginx

[root@slave1 nginx-1.5.3]# date
Tue Sep 12 22:36:30 CST 2017
[root@slave1 nginx-1.5.3]# ps -ef | grep nginx
root       5371      1  0 21:59 ?        00:00:00 nginx: master process /usr/local/nginx/sbin/nginx -c /usr/local/nginx/conf/nginx.conf
www        5372   5371  0 21:59 ?        00:00:00 nginx: worker process
www        5373   5371  0 21:59 ?        00:00:00 nginx: worker process
www        5374   5371  0 21:59 ?        00:00:00 nginx: worker process
www        5375   5371  0 21:59 ?        00:00:00 nginx: worker process
www        5376   5371  0 21:59 ?        00:00:00 nginx: worker process
www        5377   5371  0 21:59 ?        00:00:00 nginx: worker process
www        5378   5371  0 21:59 ?        00:00:00 nginx: worker process
www        5379   5371  0 21:59 ?        00:00:00 nginx: worker process
root       9142   9141  0 22:36 ?        00:00:00 sh -c /usr/local/chk_nginx_pid.sh
root       9143   9142  0 22:36 ?        00:00:00 vi /usr/local/chk_nginx_pid.sh
root       9149   2537  0 22:36 pts/0    00:00:00 grep --color=auto nginx
[root@slave1 nginx-1.5.3]# kill -quit 5371
[root@slave1 nginx-1.5.3]#

在查看slave1上的ip信息（没有了199）