Pen - Load Balance2011/06/05

	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.srv.world [10.0.0.50] - Pen Server (2) www01.srv.world [10.0.0.51] - Web Server#1 (3) www02.srv.world [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

# 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

# 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.

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