Developing on AWS or GCE

When running benchmarks or resource intensive stress tests, it can be helpful to run on a GCE or AWS instance -- trying to do anything else (even just web browsing) can be difficult, plus laptops have highly variable performance (both due to running other things and hardware doing thermal/power management) making their timings unreliable.

Auto-shutdown when not in use

Since usage is billed by the hour, automatically shutting down when not in use saves $. A cron job can check if you are logged in and start a shutdown if not. Waiting 10mins prevents shutting down before you get a chance to login or if you briefly disconnect, and checking if /.active exists allows easily disabling this temporarily when you want to leave something running unattended.

1. Put the following in /root/idle.sh:

   #!/bin/bash
   
   who=david
   
   # bail if I'm logged in or I've signaled I want to stay running.
   if w | grep -q $who || [[ -f /.active ]]; then exit; fi
   
   echo "shutdown in 10 min" | wall
   sleep 600
   
   if w | grep -q $who || [[ -f /.active ]]; then exit; fi
   
   /sbin/shutdown -h now

2. Make it executable: chmod +x /root/idle.sh

3. Edit root's cron with sudo crontab -e to add:

   * * * * * /root/idle.sh 2>&1 >> /root/idle.log
   

4. Add sudo rm /.active to your ~/.bashrc (or whatever) to clear the .active file on next login.