Nginx+keepalive

2024-06-28 14:32:57

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1 規劃和準備

兩臺相同配置的web
用途	ip
MASTER	192.168.1.100
BACKUP	192.1681.101

2 安裝

兩臺接入服務器分別安裝NginX和keepalived:

準備依賴包：

yum -y install gcc pcre-devel zlib-devel openssl-develyum -y install popt-devel

下載

wget http://nginx.org/download/nginx-1.2.4.tar.gz wget http://www.keepalived.org/software/keepalived-1.2.7.tar.gz

安裝NginX

安裝keepalive

tar zxvf keepalived-1.2.7.tar.gzcd keepalived-1.2.7./configuremake make installcp /usr/local/etc/rc.d/init.d/keepalived /etc/rc.d/init.d/cp /usr/local/etc/sysconfig/keepalived /etc/sysconfig/mkdir /etc/keepalivedcp /usr/local/etc/keepalived/keepalived.conf /etc/keepalived/cp /usr/local/sbin/keepalived /usr/sbin/

加入啟動服務

echo "/usr/local/nginx/sbin/nginx" >> /etc/rc.localecho "/etc/init.d/keepalived start" >> /etc/rc.local

3 配置

3.1 配置NginX

　　兩臺接入服務器的NginX的配置完全一樣,主要是配置/usr/local/nginx/conf/nginx.conf的http。其中多域名指向是通過虛擬主機（配置http下面的server）實現；同一域名的不同虛擬目錄通過每個server下面的不同location實現；到后端的服務器在http下面配置upstream,然后在server或location中通過PRoxypass引用。要實現前面規劃的接入方式，http的配置如下：

http {    include       mime.types;    default_type  application/octet-stream;    sendfile        on;    upstream dev.hysec.com {        server 50.1.1.21:80;    }    upstream opslinux.com {      ip_hash;      server 192.168.1.102:80      server 192.168.1.103:80      server 192.168.1.104:80    }    server {        listen       80;        server_name  opslinux.com;        location / {            proxy_pass http://opslinux.com;        }}

驗證方法：

首先用IP訪問前表中各個應用服務器的url

再用域名和路徑訪問前表中各個應用系統的域名/虛擬路徑

3.2 配置keepalived

按照上面的安裝方法，keepalived的配置文件在/etc/keepalived/keepalived.conf。主、從服務器的配置相關聯但有所不同。如下：

Master:! Configuration File for keepalivedglobal_defs {  router_id NGINX_DEVEL}vrrp_instance VI_1 {    state MASTER    interface eth0    virtual_router_id 51    priority 101    advert_int 1    authentication {        auth_type PASS        auth_pass 1111    }    virtual_ipaddress {       192.168.1.100    }}Backup:! Configuration File for keepalivedglobal_defs {  router_id NGINX_DEVEL}vrrp_instance VI_1 {    state BACKUP    interface eth0    virtual_router_id 51    priority 99    advert_int 1    authentication {        auth_type PASS        auth_pass 1111    }    virtual_ipaddress {       192.168.1.100    }}

驗證：

先后在主、從服務器上啟動keepalived: /etc/init.d/keepalived start

在主服務器上查看是否已經綁定了虛擬IP： ip addr

停止主服務器上的keepalived: /etc/init.d/keepalived stop 然后在從服務器上查看是否已經綁定了虛擬IP：

啟動主服務器上的keepalived，看看主服務器能否重新接管虛擬IP

3.3 讓keepalived監控NginX的狀態

經過前面的配置，如果主服務器的keepalived停止服務，從服務器會自動接管VIP對外服務；一旦主服務器的keepalived恢復，會重新接管VIP。但這并不是我們需要的，我們需要的是當NginX停止服務的時候能夠自動切換。

keepalived支持配置監控腳本，我們可以通過腳本監控NginX的狀態，如果狀態不正常則進行一系列的操作，最終仍不能恢復NginX則殺掉keepalived，使得從服務器能夠接管服務。

如何監控NginX的狀態

最簡單的做法是監控NginX進程，更靠譜的做法是檢查NginX端口，最靠譜的做法是檢查多個url能否獲取到頁面。

如何嘗試恢復服務

如果發現NginX不正常，重啟之。等待3秒再次校驗，仍然失敗則不再嘗試。

根據上述策略很容易寫出監控腳本。這里使用nmap檢查nginx端口來判斷nginx的狀態，記得要首先安裝nmap。監控腳本如下:

#!/bin/bash# check nginx server statusNGINX=/usr/local/nginx/sbin/nginxPORT=8080nmap localhost -p $PORT | grep "$PORT/tcp open"#echo $?if [ $? -ne 0 ];then    $NGINX -s stop    $NGINX    sleep 3    nmap localhost -p $PORT | grep "$PORT/tcp open"    [ $? -ne 0 ] && /etc/init.d/keepalived stopfi

不要忘了設置腳本的執行權限，否則不起作用。

假設上述腳本放在/opt/chk_nginx.sh，則keepalived.conf中增加如下配置：

主keepalivedvrrp_script chk_http_port {    script "/opt/chk_nginx.sh"    interval 1    weight -2}track_script {    chk_http_port}例子：! Configuration File for keepalivedglobal_defs {   router_id NGINX_UPSTEAM}vrrp_script chk_http_port {    script "/opt/chk_nginx.sh"    interval 1    weight -2}vrrp_instance VI_1 {    state MASTER    interface eth0    virtual_router_id 51    priority 100    advert_int 1    authentication {        auth_type PASS        auth_pass 1111    }    virtual_ipaddress {        192.168.1.100    }    track_script {    chk_http_port    }}

更進一步，為了避免啟動keepalived之前沒有啟動nginx , 可以在/etc/init.d/keepalived的start中首先啟動nginx:

start() {    /usr/local/nginx/sbin/nginx    sleep 3    echo -n $"Starting $prog: "    daemon keepalived ${KEEPALIVED_OPTIONS}    RETVAL=$?    echo    [ $RETVAL -eq 0 ] && touch /var/lock/subsys/$prog}