Can someone please explain to me the difference between fleet spawn and fleet exec?
Also - is there any way for the executing process / drone to send a message back to the hub?
fleet exec runs a command on the drone and prints the output.
fleet spawn runs a command and restarts the command when it exits.
I'm not sure what sort of message you'd like to send to the hub. Anything you print on stderr or stdout gets sent to the hub and you can see what's happening everywhere with fleet monitor.