At [mkanoap’s] office, they have a software package that monitors their various servers’ health, but they wanted a separate indicator to display the status of their most critical systems. They put together a simple list of criteria for their display, including the ability to view the status without a computer, and that it share the same red/yellow/green indicators that their monitoring software utilizes. With those needs in mind (and a few hundred dollars to spare), [mkanoap] and crew rushed out to buy a stoplight, then got to building.
Their status system is self-contained, utilizing an Arduino and Ethernet shield to control the stoplight. The Arduino was programmed to act as a web server, and responds to GET requests by toggling any of the three mains-powered lamps using relays. [mkanoap] then created a handful of scripts that check the status of the critical servers every 5 minutes, updating the stoplight accordingly. The whole setup was tucked neatly inside the light’s housing, before being mounted on the wall in their office.
[mkanoap] says that the reaction to the stoplight as been great, though they had to install dimmer bulbs so those people sitting near it were not blinded. His writeup is incredibly detailed should anyone want to construct one of their own, and who wouldn’t?