JunOS Service restart via cronjob

Some days ago we had trouble on one of our QFXes where the jdhcpd deamon would consume 100% CPU and “crash” – resulting in users not getting IP’s anymore.
While TAC is still investigating, I made a quick Workaround for this – the DHCP-Sheriff 😉


current=$(top | grep jdhcpd | awk '{ print $10 }')

if [ ${current%.*} -eq ${desired%.*} ] && [ ${current#*.} \> ${desired#*.} ] || [ ${current%.*} -gt ${desired%.*} ]; then

echo "$(date)" >> /var/log/dhcp-sheriff.log >> /var/log/dhcp-sheriff.log
echo The current load of dhcp-service is above desired value - restarting the service >> /var/log/dhcp-sheriff.log
echo "${current} >= ${desired}" >> /var/log/dhcp-sheriff.log
cli restart dhcp-service
echo "" >> /var/log/dhcp-sheriff.log;


echo "$(date)" >> /var/log/dhcp-sheriff.log
echo The current load of dhcp-service is below desired value - no action needed >> /var/log/dhcp-sheriff.log
echo "${current} <= ${desired}" >> /var/log/dhcp-sheriff.log
echo "" >> /var/log/dhcp-sheriff.log;



This Script restarts the Service if the load of the Service is above 1% (adjustable) – this can be easily adopted to other services and thresholds.

1.) Login as root and in shell type: vi /var/tmp/dhcp-sheriff.sh

2.) Press “i” and paste the above lines, followed by “[Esc-Button]”. Save and Quit with :wq

chmod +x /var/tmp/dhcp-sheriff.sh

crontab -e
0 */8 * * * sh /var/tmp/dhcp-sheriff.sh (executes it every 8h)


crontab -l
0 */8 * * * sh /var/tmp/dhcp-sheriff.sh

6.) in cli check after job has finished to run via show log dhcp-sheriff.log


Feel free to use this to your advantage – hopefully this will be a workaround for you in urgent-times until a fix is released.
This is only a workaround – do not use this in production for a long time / use at your own risk.

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