Nginx 負載均衡（主備）+Keepalived

Nginx負載均衡器的優點:

實現看彈性化操作的架構，壓力增大的時候可以臨時添加后端Web服務器；

upstream具有負載均衡能力 (默認使用輪詢) ，可以自動判斷下面的機器，并且自動踢出不能正常提供服務的機器；

Keepalvied加Nginx監測腳本可保證單個nginx負載均衡器的有效性,避免單點故障

IP地址

nginx( 主LB ):192.168.1 5.132

nginx( 備LB ):192.168.15.133

VIP 地址 :192.168.15.135

Real 的 IP:192.168.1 5.128

Real 2 的 IP:192.168.1 5.130

部署整個環境用到的軟件為 :

zlib-1.2.8.tar.gz

① 2 臺 Web 主機（Ubuntu）上部署環境 ， 安裝 Nginx+PHP-FPM+MySQL

② 分別在二臺 Nginx 負載均衡器上安裝 Nginx 及配置

安裝GCC編譯器等工具：

yum install -y gcc gcc-c++ autoconf automake libtool make openssl openssl-devel

安裝 Nginx:

wget http://exim.mirror.fr/pcre/pcre-8.38.tar.gz

tar -zxvf pcre-8.38.tar.gz

cd pcre-8.38

./configure

make && make install

wget http://zlib.net/zlib-1.2.8.tar.gz

tar -zxvf zlib-1.2.8.tar.gz

cd zlib-1.2.8

./configure

make && make install

wget http://nginx.org/download/nginx-1.6.3.tar.gz

./configure --prefix=/usr/local/nginx

--sbin-path=/usr/local/nginx/sbin/nginx

--conf-path=/usr/local/nginx/conf/nginx.conf

--pid-path=/usr/local/nginx/logs/nginx.pid \

--with-http_ssl_module \

--with-http_stub_status_module \

--with-http_gzip_static_module \ 

make && make install 

注：查詢"./configure --help"相關模塊，按需求指定啟用

Nginx.conf 配置文件 ， 二個 nginx 負載均衡器的文件一樣

user  www-data www-data;
worker_processes  1;
error_log  /usr/local/nginx/logs/error.log notice;
pid        /usr/local/nginx/logs/nginx.pid;
worker_rlimit_nofile 51200;
events {
    use epoll;
    worker_connections  51200;
}
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;
    server_names_hash_bucket_size 128;
    client_header_buffer_size 32k;
    large_client_header_buffers 4 32k;
    client_max_body_size 8m;
    sendfile        on;
    tcp_nopush     on;
    server_tokens off;
    keepalive_timeout  60;
    fastcgi_connect_timeout 300;
    fastcgi_send_timeout 300;
    fastcgi_read_timeout 300;
    fastcgi_buffer_size 64k;
    fastcgi_buffers 4 64k;
    fastcgi_busy_buffers_size 128k;
    fastcgi_temp_file_write_size 128k;
    gzip  on;
    upstream backend
    {
    server 192.168.15.128;
    server 192.168.15.130;
    }
    server {
        listen       80;
        server_name  192.168.15.135;
        location / {
            root   html;
            index  index.php index.html index.htm;
            proxy_redirect off;
            proxy_set_header Host $host;
            proxy_set_header X-Real-IP $remote_addr;
            #后端的Web服務器可以通過X-Forwarded-For獲取用戶真實IP
            proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
            proxy_pass http://backend;
        }
        error_page   500 502 503 504  /50x.html;
        location = /50x.html {
            root   html;
        }

        location /nginx_status {
            stub_status on; 
            auth_basic "NginxStatus";
            auth_basic_user_file /usr/local/nginx/htpasswd;
            #allow 127.0.0.1;
            #deny all;
        }
        location ~* \.(ini|docx|txt|doc|pdf)$ {
        #禁止訪問文檔性文件
        root /usr/share/nginx/html;
        deny all;
        }
        location ~ .*\.(gif|jpg|jpeg|png|bmp|swf|js|html|htm|css)$ {
        root /home/image;
        proxy_store on;
        proxy_store_access user:rw group:rw all:rw;
        proxy_temp_path /home/image;
        if ( !-e $request_filename) {
           proxy_pass  http://backend;
        }
    }
}
}

③ 在二臺 Nginx 上安裝及配置 keepali ved：

wget http://www.keepalived.org/software/keepalived-1.2.15.tar.gz

tar -zxvf keepalived-1.2.15.tar.gz

cd keepalived-1.2.15

./configure --sysconf=/etc/  --with-kernel-dir=/usr/src/kernels/2.6.32-573.8.1.el6.x86_64

make && make install

ln -s /usr/local/sbin/keepalived  /sbin/  

#這一步很重要，不執行ln -s會報錯“Starting keepalived: /bin/bash: keepalived: command not found”

service keepalived start

二臺 Nginx 上 keepalived.conf 配置文件如下 ， 配置完成后分別 service keepalived start 啟動 ? 檢驗 keepalived配置 是否成功

主：

global_defs {
   notification_email {
     test@163.com
   }
   notification_email_from keepalived@localhost 
   smtp_server 127.0.0.1
   smtp_connect_timeout 30
   router_id LVS_MASTER
}
vrrp_script chk_http_port {
script "/usr/local/src/check_nginx_pid.sh"
interval 2                           #（檢測腳本執行的間隔）
weight 2
}
vrrp_instance VI_1 {
    state MASTER
    interface bond0
    virtual_router_id 51
    priority 100
    advert_int 1
    authentication {
        auth_type PASS
        auth_pass 1111
}
track_script {
chk_http_port            #（調用檢測腳本）
}
    virtual_ipaddress {
        192.168.15.135
    }
}

備： 

global_defs {
   notification_email {
     test@163.com
   }
   notification_email_from keepalived@localhost 
   smtp_server 127.0.0.1
   smtp_connect_timeout 30
   router_id LVS_BACKUP
}
vrrp_script chk_http_port {
script "/usr/local/src/check_nginx_pid.sh"
interval 2                           #（檢測腳本執行的間隔）
weight 2
}
vrrp_instance VI_1 {
    state BACKUP
    interface bond0
    virtual_router_id 51
    priority 66
    advert_int 1
    authentication {
        auth_type PASS
        auth_pass 1111
}
track_script {
chk_http_port            #（調用檢測腳本）
}
    virtual_ipaddress {
        192.168.15.135
    }
}

以下是針對nginx狀態進行檢測的腳本，第一次nginx服務死掉時，會重新啟動，如果Nginx服務無法正常啟動，則殺掉keepalived進程

vim  /usr/local/src/check_nginx_pid.sh

#!/bin/bash
A=`ps -C nginx --no-header |wc -l`        
if [ $A -eq 0 ];then                            
      /usr/local/nginx/sbin/nginx        
      if [ `ps -C nginx --no-header |wc -l` -eq 0 ];then  
              killall keepalived                    
      fi
fi

Ok，開始nginx 負載均衡測試， 停掉其中一臺的任何服務， 不影響整個系統的運作 ?

注：兩臺LBServer也可分別添加一個VIP①②（Keepalived心跳監控，服務不可用或者宕機，VIP①被備LBServer接管），外部使用智能DNS輪詢兩個VIP①②， 提高硬件資源利用率 。