OK Computer

Inspired by the ease of installing and setting up fitter-happier as a Rails application's health check, but frustrated by its lack of flexibility, OK Computer was born. It provides a robust endpoint to perform server health checks with a set of built-in plugins, as well as a simple interface to add your own custom checks.

Installation

Add this line to your application's Gemfile:

gem 'okcomputer'

And then execute:

$ bundle

Or install it yourself as:

$ gem install okcomputer

Usage

To perform the default checks (application running and ActiveRecord database connection), do nothing other than adding to your application's Gemfile.

If Not Using ActiveRecord

We also include a MongoidCheck, but do not register it. If you use Mongoid, replace the default ActiveRecord check like so:

OKComputer::Registry.register "database", OKComputer::MongoidCheck.new

If you use another database adapter, see Registering Custom Checks below to build your own database check and register it with the name "database" to replace the built-in check, or use OKComputer::Registry.deregister "database" to stop checking your database altogether.

Registering Additional Checks

Register additional checks in an initializer, like do:

# config/initializers/okcomputer.rb
OKComputer::Registry.register "resque_down", OKComputer::ResqueDownCheck.new("critical", 100)
OKComputer::Registry.register "resque_backed_up", OKComputer::ResqueBackedUpCheck.new

Registering Custom Checks

The simplest way to register a check unique to your application is to subclass OKComputer::Check and implement your own #call method, which returns the output string, and calls mark_failure if anything is wrong.

# config/initializers/okcomputer.rb
class MyCustomCheck < OKComputer::Check
  def call
    if rand(10).even?
      "Even is great!"
    else
      mark_failure
      "We don't like odd numbers"
    end
  end
end

OKComputer::Registry.register "check_for_odds", MyCustomCheck.new

Performing Checks

• Perform a simple up check: http://example.com/okcomputer
• Perform all installed checks: http://example.com/okcomputer/all
• Perform a specific installed check: http://example.com/okcomputer/database

Checks are available as plain text (by default) or JSON by appending .json, e.g.:

• http://example.com/okcomputer.json
• http://example.com/okcomputer/all.json

Contributing

1. Fork it
2. Create your feature branch (git checkout -b my-new-feature)
3. Commit your changes (git commit -am 'Add some feature')
4. Push to the branch (git push origin my-new-feature)
5. Create new Pull Request