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A while ago I wrote a post about sysfence. http://www.computersolutions.cn/blog/2010/12/debian-system-load-monitoring/

As it really was a while ago, I’ll recap quickly.

Sysfence is a small, light system monitoring app that has a nice heavy hand. If load goes over user defined limits, it will kill processes specified in its config (with extreme prejudice), and only start them up again once load is back under a certain level.

Got that?

Ok.

sysfence is rather good at what it does, fits my needs, so I’ve continued to use it over the years. One of the things I never got around to doing was making a startup script for it – this is mostly as it works as advertised – i’ve had zero issues!

That said, someone finally called my bluff and asked me for my startup script, which of course, I didn’t have, so I made one this morning.

The script is debian biased, and depends on where you installed sysfence.

You’ll need 3 files as below. Change settings to your needs.

1) Basic settings for sysfence

/etc/default/sysfence


SYSFENCE_ENABLE=true #Are we enabled (er, yes!)
DAEMON_OPTS=" /etc/sysfence/sysfence.conf" #Where is our ruleset
MAILTO="root" #Who to call in case of issues.

2) Config file for sysfence

/etc/sysfence/sysfence.conf


#[Your sysfence watch rules goes here]
#My example below

rule "Apache" {
la1 >= 6.00 or la5 >= 3.5
}
run '/usr/sbin/apache2ctl stop; sleep 120; /usr/sbin/apache2ctl start'
rule "warning" { la1 >= 6.00 } run once 'echo "Load High: $HOSTNAME" | mail $MAILTO'

3) Debian Startup script


#!/bin/sh
### BEGIN INIT INFO
# Provides: sysfence
# Required-Start: $local_fs $remote_fs
# Required-Stop: $local_fs $remote_fs
# Should-Start: $network
# Should-Stop: $network
# Default-Start: 2 3 4 5
# Default-Stop: 0 1 6
# Short-Description: Daemonized version of sysfence
# Description: Starts the sysfence daemon
# /etc/default/sysfence.
### END INIT INFO
# Author: L. Sheed

#The complete default command that is being run is:
#sysfence " /etc/sysfence/sysfence.conf"
#obviously this will change with your variables,
#but the entire command is here for testing
# uses /etc/default/sysfence

NAME="sysfence"
SYSFENCE_ENABLE=false
DESC="sysfence Daemon"

DAEMON=`which sysfence`
DAEMON1="sffetch"
DAEMON2="sfwatch"
LOGFILE="/var/log/sysfence.log"

test -x $DAEMON || exit 0

if [ ! -e "${LOGFILE}" ]
then
touch "${LOGFILE}"
chmod 640 "${LOGFILE}"
chown root:adm "${LOGFILE}"
fi

. /lib/lsb/init-functions

if [ -f /etc/default/$NAME ]; then
. /etc/default/$NAME
case "x$SYSFENCE_ENABLE" in
xtrue|x1|xyes)
SYSFENCE_ENABLE=true
;;
*)
SYSFENCE_ENABLE=false
exit 1;
;;
esac
fi

case "$1" in
start)
PID=`ps aux | grep "$DAEMON1 " | grep -v grep | awk '{print $2}'`
if [ "x$PID" != "x" ]; then
echo `date` " * $NAME appears to be already running!" | tee -a $LOGFILE
exit
fi
if $SYSFENCE_ENABLE; then
echo "Starting $DESC"
log_daemon_msg "Starting $DESC" "$NAME"
$DAEMON $DAEMON_OPTS

PID=`ps aux | grep "$DAEMON1 " | grep -v grep | awk '{print $2}'`
echo " * $NAME PID is $PID"
echo "Watching:"
ps -ef | grep "$DAEMON2 " | grep "$PID"
else
log_warning_msg "Not starting $DESC $NAME, disabled via /etc/default/$NAME"
fi
;;

stop)
if $SYSFENCE_ENABLE; then
PID=`ps aux | grep "$DAEMON1 " | grep -v grep | awk '{print $2}'`
if [ "x$PID" = "x" ]; then
echo " * $NAME is not running"
else
echo " Stopping $NAME"
log_daemon_msg "Stopping $DESC" "$NAME"
kill $PID
fi
fi
;;

status)
PID=`ps aux | grep "$DAEMON1 " | grep -v grep | awk '{print $2}'`
if [ "x$PID" = "x" ]; then
echo " * $NAME is not running"
else
echo " * $NAME PID is $PID"
echo "Watching:"
ps -ef | grep "$DAEMON2 " | grep "$PID"
fi
;;

*)
N=/etc/init.d/$NAME
echo "Usage: $N {start|stop|status}" >&2
exit 1
;;
esac

exit 0;

You can download the init script here – sysfence init script for debian

Yikes, I almost forgot the other bit of this post. Tsk tsk…

The makefile doesn’t make in some of my servers. Its probably that dash shell expansion breaks stuff vs bash, but haven’t investigated it properly.

This is a simple fix

open up the makefile and change the expansion stuff to explicitly list the .o files.

eg

Makefile says:

CC=gcc
LDFLAGS=
CFLAGS=-Wall -O2
objects=conditions.o getstats.o mainloop.o cp2memory.o datastruct.o sysfence.o
parseopt=parseopt/{confread,lex,parse}.o
sys=sys/{exit,xalloc,log,communication,sighandlers,processtitle,users}.o
... (rest of the file)

Change to:


CC=gcc
LDFLAGS=
CFLAGS=-Wall -O2
objects=conditions.o getstats.o mainloop.o cp2memory.o datastruct.o sysfence.o
parseopt=parseopt/confread.o parseopt/lex.o parseopt/parse.o
sys=sys/exit.o sys/xalloc.o sys/log.o sys/communication.o sys/sighandlers.o sys/processtitle.o sys/users.o
... (rest of the file)

make clean

and

make

Simple!

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