Hi,

I suggest you monitor load rather than cpu usage, it gives you the overall state of the machine...
You can create your own script to notify you in cases that high loads occur:

#!/bin/bash

mail="mail@example.com"
maxload="10"
hn=`hostname`
load=`w | head -n1 | awk '{print$10}' | cut -d"," -f1`

if [ $load -gt $maxload ]; then
echo "Oh no, system load higher than $maxload detected..."
echo "Alerting $mail"
echo "$hn High Load Found." | mail -s "$hn High Load Found." -- $mail
else
echo "OK"
fi

Apologies for jumping in here.

@yoavz.z - what exactly is 'load' and presumably there is a command to view the current load in Linux?

Thanks.

You can install "monit": https://www.digitalocean.com/community/articles/how-to-install-and-configure-monit

"... what exactly is 'load'..."

From From Wikipedia:

In UNIX computing, the system load is a measure of the amount of computational work that a computer system performs. The load average represents the average system load over a period of time. It conventionally appears in the form of three numbers which represent the system load during the last one-, five-, and fifteen-minute periods.
...

CPU load vs CPU utilization

The comparative study of different load indices carried out by Ferrari et al.[4] reported that CPU load information based upon the CPU queue length does much better in load balancing compared to CPU utilization. The reason CPU queue length did better is probably because when a host is heavily loaded, its CPU utilization is likely to be close to 100% and it is unable to reflect the exact load level of the utilization. In contrast, CPU queue lengths can directly reflect the amount of load on a CPU. As an example, two systems, one with 3 and the other with 6 processes in the queue, are both very likely to have utilizations close to 100% although they obviously differ.

Thanks @yoavz.z! I've implemented exactly that.

Just installed monit too. thank you drapko.

@yoavz.z,

Would you mind adding your script to DigitalOcean User Projects | GitHub?