god monitors your server processes and tasks to make sure they run smoothly, and performs maintenance tasks (such as restarting your application servers) as necessary. This Ruby application is written by Tom Preston-Werner and serves similar functionality to, and inspired by, a popular tool called monit.

Among the features god provides include:

• Config file is written in Ruby
  Easily write your own custom conditions in Ruby
  Supports both poll and event based conditions
  Different poll conditions can have different intervals

Here's a part of an example config file used to monitor mongrel instances:

god.watch do |w|
  w.name = "gravatar2-mongrel-#{port}"
  w.interval = 30 # seconds
  w.start = "mongrel_rails cluster::start --only #{port}
    -C #{RAILS_ROOT}/config/mongrel_cluster.yml"
  w.stop = "mongrel_rails cluster::stop --only #{port}
    -C #{RAILS_ROOT}/config/mongrel_cluster.yml"
  w.grace = 10 # seconds

  ...
end

Monit users (including myself) will instantly recognize the mapping between monit rules/tests and the ones in a god config file. The main difference and advantage is, because god uses the Ruby language, you can have all sorts of advanced tests, loops, and even include your own extensions like modules and mixins. God actually supports an official mechanism for this purpose.

Install god using Rubygems:

sudo gem install god -y

The god web page has thorough information and you can also browse the source code directly.