monit用 Monit 監(jiān)測 linux 服務(wù)器
Monit 是一個用來監(jiān)測系統(tǒng)狀態(tài)的工具，不但可以用來監(jiān)視進程、服務(wù)、文件、目錄、文件系統(tǒng)，還可以在服務(wù) down 掉的時候自動重啟服務(wù)或者當某個進程占用過多的資源的時候自動停掉進程，并且支持 Email 報警功能、遠程服務(wù)器監(jiān)測、web 管理界面等，功能很多很強大。VPSee 用 monit 來監(jiān)測多個 VPS 和獨立服務(wù)器，如果某個 VPS down 了、某個服務(wù)器資源緊張，就能第一時間知道，而且某個服務(wù)停了的話可以自動重啟服務(wù)。
安裝 monit
在 CentOS 下安裝和配置文件：
# wget http://packages.sw.be/rpmforge-release/rpmforge-release-0.3.6-1.el5.rf.i386.rpm
# rpm -Uvh rpmforge-release-0.3.6-1.el5.rf.i386.rpm
# yum install monit
# vi /etc/monit.conf
配置 monit
修改 monit 的配置文件，/etc/monit.conf（CentOS）或者 /etc/monit/monitrc（Debian），每隔120秒檢查一次系統(tǒng)，如果 httpd/mysql/sshd 服務(wù)停掉了就重新啟動相應(yīng)服務(wù)。對于 httpd 服務(wù)器，當發(fā)現(xiàn) CPU/MEM 占用過大、loadavg 太高時就執(zhí)行相應(yīng)的報警、重啟服務(wù)指令。如果使用 Email 報警功能，需要配置 Email 地址、郵件服務(wù)器等信息：
set daemon 120
check process sshd with pidfile /var/run/sshd.pid
start program “/etc/init.d/sshd start”
stop program “/etc/init.d/sshd stop”
if failed port 22 protocol ssh then restart
if 5 restarts within 5 cycles then timeout
check process mysql with pidfile /var/run/mysqld/mysqld.pid
group database
start program = “/etc/init.d/mysqld start”
stop program = “/etc/init.d/mysqld stop”
if failed host 127.0.0.1 port 3306 then restart
if 5 restarts within 5 cycles then timeout
check process nginx with pidfile /var/run/nginx.pid
start program = “/etc/init.d/nginx start”
stop program = “/etc/init.d/nginx stop”
if failed host www.yanghengfei.com port 80 protocol http
then restart
check process php_cgi with pidfile /var/run/php_cgi.pid
start program = “/etc/init.d/php_cgi start”
stop program = “/etc/init.d/php_cgi stop”
if failed host 127.0.0.1 port 9000 then restart
if 5 restarts within 5 cycles then timeout
check process apache with pidfile /var/run/httpd.pid
group www
start program = “/etc/init.d/httpd start”
stop program = “/etc/init.d/httpd stop”
if failed host www.yanghengfei.com port 8080 protocol http
then restart
if cpu is greater than 80% for 2 cycles then alert
if cpu > 80% for 5 cycles then restart
if totalmem > 512 MB for 5 cycles then restart
if children > 200 then restart
if loadavg(5min) greater than 10 for 8 cycles then stop
if 3 restarts within 5 cycles then timeout
更多詳細信息可以參考配置文件，里面注釋寫得很詳細。
啟動 monit
在 CentOS 下啟動并加入到系統(tǒng)啟動腳本：
# /etc/init.d/monit start
# /sbin/chkconfig monit on
