If you publish .../echo to the topic the monitor nodes are on, it will respond back ok. Every minute I publish and then listen for the response, if it fails for 5 min it sends a reboot command.
Monitor usually locks up and the pi is still accessible. I reboot with a shell command over ssh
restart104: ssh -i /config/ssh/id_rsa2 -o 'StrictHostKeyChecking=no' [email protected] sudo shutdown -r
