Web server Load Balance Pen

Install Pen to configure Load Balance server. Pen is a light weight simple load balancer. This example shows to configure on the environment like follows.
        (1)  gw.horoppa.net         [10.0.0.50]  -  Pen Server
        (2)  www01.horoppa.net   [10.0.0.51]  -  Web Server#1
        (3)  www02.horoppa.net   [10.0.0.52]  -  Web Server#2
[1] Install and Configure Pen

[root@gw ~]#  yum --enablerepo=epel -y install pen     # install from EPEL [root@gw ~]#  vi /etc/pen.conf # create new # log file LOGFILE=/var/log/pen.log # output file of status WEBFILE=/var/www/pen/webstats.html # control port CONTROL=127.0.0.1:10080 # max connections MAX_CONNECTIONS=500 # listen port PORT=80 # number of backend servers BACKEND=2 # IP address of a backend SERVER1=10.0.0.51:80 # IP address of a backend SERVER2=10.0.0.52:80 [root@gw ~]#  vi /etc/rc.d/init.d/pend # create init script # this is an example #!/bin/bash # pend: Start/Stop Pend # chkconfig: - 90 10 # description: Pen is a light weight simple load balancer. # pidfile: /var/run/pen.pid . /etc/rc.d/init.d/functions . /etc/sysconfig/network . /etc/pen.conf LOCKFILE="/var/lock/subsys/pen" PID=/var/run/pen.pid PROG=/usr/bin/pen RETVAL=0 start() { echo -n $"Starting Pend: " SERVER=`grep "^SERVER" /etc/pen.conf | cut -d= -f2` daemon $PROG -w $WEBFILE -x $MAX_CONNECTIONS -p $PID -l $LOGFILE -C $CONTROL -S $BACKEND -r $PORT $SERVER RETVAL=$? echo [ $RETVAL -eq 0 ] && touch $LOCKFILE return $RETVAL } stop() { echo -n $"Stopping Pend: " killproc $PROG RETVAL=$? echo [ $RETVAL -eq 0 ] && rm -f $PID $LOCKFILE return $RETVAL } case "$1" in start) start ;; stop) stop ;; status) status pend ;; restart) stop start ;; *) echo $"Usage: $0 {start|stop|status|restart}" exit 1 esac exit $? [root@gw ~]#  vi /etc/logrotate.d/pen # setting of logrotation # this is an example /var/log/pen.log { daily copytruncate compress notifempty missingok postrotate /etc/rc.d/init.d/pend restart 2>&1 > /dev/null || true endscript } [root@gw ~]#  chmod 755 /etc/rc.d/init.d/pend  [root@gw ~]#  /etc/rc.d/init.d/pend start  Starting Pend: [ OK ] [root@gw ~]#  chkconfig --add pend  [root@gw ~]#  chkconfig pend on

[2]	Access to the URL you set and make sure backend server answers normally like follows.

[3]	Shutdown other httpd manually and make sure another httpd answers normally like follows.

[4]	Configure the tool that it's possible to watch Pen's status.

[root@gw ~]#  cp /usr/share/doc/pen-*/penstats /var/www/pen  [root@gw ~]#  vi /var/www/pen/penstats # line 4: change PIDFILE= /var/run/pen.pid # line 5: change WEBFILE= /var/www/pen/webstats.html [root@gw ~]#  vi /etc/httpd/conf.d/pen.conf # change Alias  /pen/ /var/www/pen/ <Directory /var/www/pen/>    DirectoryIndex penctl.cgi    Options ExecCGI    order deny,allow    deny from all    allow from 127.0.0.1  10.0.0.0/24     # IP address you permit </Directory> [root@gw ~]#  /etc/rc.d/init.d/httpd restart  Stopping httpd:  [ OK ] Starting httpd:  [ OK ] [root@gw ~]#  chmod 755 /var/www/pen/penstats  [root@gw ~]#  /var/www/pen/penstats > /dev/null     # run [root@gw ~]#  crontab -e # update by 5 minutes */5 * * * * /var/www/pen/penstats > /dev/null

[5]	Access to "http://(pen's hostname or IP address):(httpd listen port)/pen/webstats.html" and make sure following site is shown normally.