"If all else fails, immortality can always be assured by spectacular error."—J.K. Galbraith
Trouble has a way of sneaking up on you like a bug on a windshield. The standard checks provided by monitoring tools like Nagios don't always cover everything you want to monitor. While metrics such as load average and disk space can be useful problem indicators', I like to be able to get higher-level information about the applications and services my machines provide.
For example, if you are running a web application, it's not enough to know that the web server is listening to connections on port 80 and responding with an
HTTP 200 OK status. It could just be returning the default Apache welcome page.
If your web application ...