Howto use standalone engine in clustering! (The linux answer I found)

Kevin nnoydb at excite.com
Wed Mar 10 17:54:28 EST 2004



Okay, here is my solution it is messy but gets the job done.

Create a user with very little access for my purposes I will call it 'clustergui'. 

Manually execute vncserver and set the vnc password to something very secure!

Create a init.d script (or use the one below) to initialize a vncserver secession (protected by local firewall) for user 'clustergui'.  

Add 127.0.0.1 aka locahost to your system xhost (this gives 127.0.0.1 aka localhost the right to mount the gui you just created).

Execute the program like so:

rrprogram -display 127.0.0.1:<display#> 

Note: You can set the DISPLAY environment varaible to 127.0.0.1:<display#> for entire cluster.

Because the firewall is protecting the VNC secession (preventing anyone from connecting) the secession will utilize little processor.  I also configured the ~/.vnc/xstartup to use 'twm' as the window manager (significantly lowering the memory foot-print).  Using it in this manner allows ALL GUI applications to have a X secession (not just RR standalones).  In fact I am now using matlab with bitmap function (which require X) on my cluster.

I am also using this method for my cron/console (dual mode) execution.

The scripts I used to create the secession is below.

Hope this is helpful,

Kevin



#!/bin/bash
#
# chkconfig: - 91 35
# description: Starts and stops vncserver. \
#              used to provide remote X administration services.

# Source function library.
. /etc/init.d/functions

# Source networking configuration.
. /etc/sysconfig/network

# Check that networking is up.
[ ${NETWORKING} = "no" ] && exit 0

VNCSERVERS=""
[ -f /etc/sysconfig/vncservers ] && . /etc/sysconfig/vncservers

prog=$"VNC server"

start() {
    echo -n $"Starting $prog: "
    ulimit -S -c 0 >/dev/null 2>&1
    RETVAL=0
    for display in ${VNCSERVERS}
    do
        echo -n "${display} "
        unset BASH_ENV ENV
        initlog $INITLOG_ARGS -c \
            "su ${display##*:} -l -c \"cd ~${display##*:} && [ -f .vnc/passwd ] && vncserver :${display%%:*}\""
        RETVAL=$?
        [ "$RETVAL" -ne 0 ] && break
    done
    [ "$RETVAL" -eq 0 ] && success $"vncserver startup" || \
        failure $"vncserver start"
    echo
    [ "$RETVAL" -eq 0 ] && touch /var/lock/subsys/vncserver
}

stop() {
    echo -n $"Shutting down $prog: "
    for display in ${VNCSERVERS}
    do
        echo -n "${display} "
        unset BASH_ENV ENV
        initlog $INITLOG_ARGS -c \
            "su ${display##*:} -c \"vncserver -kill :${display%%:*}\" >/dev/null 2>&1"
    done
    RETVAL=$?
    [ "$RETVAL" -eq 0 ] && success $"vncserver shutdown" || \
        failure $"vncserver shutdown"
    echo
    [ "$RETVAL" -eq 0 ] && rm -f /var/lock/subsys/vncserver
}

# See how we were called.
case "$1" in
  start)
        start
        ;;
  stop)
        stop
        ;;
  restart|reload)
        stop
        sleep 1
        start
        ;;
  condrestart)
        if [ -f /var/lock/subsys/vncserver ]; then
            stop
            start
        fi
        ;;
  status)
        status Xvnc
        ;;
  *)
        echo $"Usage: $0 {start|stop|restart|condrestart|status}"
        exit 1
esac

--------------------
Contents of /etc/sysconfig/vncservers:

# The VNCSERVERS variable is a list of display:user pairs.
#
# Uncomment the line below to start a VNC server on display :1
# as my 'myusername' (adjust this to your own).  You will also
# need to set a VNC password; run 'man vncpasswd' to see how
# to do that.  
#
# DO NOT RUN THIS SERVICE if your local area network is
# untrusted!  For a secure way of using VNC, see
# URL:http://www.uk.research.att.com/vnc/sshvnc.html.

# VNCSERVERS="1:myusername"
VNCSERVERS="100:clustergui"

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