兩臺相同配置的web | |
用途 | ip |
MASTER | 192.168.1.100 |
BACKUP | 192.1681.101 |
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
3.1 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}
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