An Automated Server Monitor

I realized some months ago, a major contributing factor to server downtime was "nobody noticing it was down". So I started checking the status of every server of every product I'm even vaguely responsible for every morning. This expanded to be quite a list over time and became a bit of a chore.

Previously, I'd write a script that hits every server API and presents summary statistics, then just run that every morning. I had a bunch of TM160 LED controller chips left over from the Catan game board though... So I figured I may as well use them. So I designed a board around the ESP8266 that sends a HTTP GET to an arbitrary list of servers, and checks whether it gets HTTP 200 or some other response.

The rounded corners and mounting holes make the board quite versatile.

How it Works

It stores an array of 9 servers -- one to check the Internet connection (I use CloudFlare) and 8 servers to monitor.

Once it connects to Wi-Fi, it turns the Wi-Fi LED on. Then it checks the first server (CloudFlare). If it gets HTTP 200, the Internet LED turns on.

After that it creates a HTTPS client, and hits the first server, processes the response, and closes the client. It repeats this for each server in the array. If The same HTTPS client just makes requests to all 9 servers, we end up with a lot of 'out of memory' crashes.

Even though it makes HTTPS requests, it does not check the security certificate. This mainly because I'm not really concerned about someone performing a MITM attack on a humble server monitor, but also because I'd have to manually load all the certificate files onto the device and checking them consumes memory.

The big patches of white silkscreen are there so you can write the server names in with whiteboard marker (if they change often), or permanent marker if they don't.

The device runs quite stable, gives me 8 fewer things to think about every morning, and is very cheap to produce. I'm quite happy with it!