Leafy-Health

installation

via rubygems

gem install leafy-health

or add to your Gemfile

gem 'leafy-health'

installing the gem also takes care of the jar dependencies with jruby-1.7.16+

usage

an instance of the registry Leafy::Health::Registry can register and unresgister health-checks under a given name. any object with a #call method will do or block on the register method.

 registry = Leafy::Health::Registry.new

you can ask the registry which names have already health-checks registered:

 registry.names

simple health check

simple in the sense that either call returns nil which means healthy or a message which is the unhealthy state. the message can be any String.

registry.register( 'simple.block') do
  if app.crashed
    'application crashed'
  end
end

or with a health-check object

class AppCheck < Leafy::Health::HealthCheck
  def call
    if app.crashed
      'application crashed'
    end
  end
end
registry.register( 'simple.class', AppCheck.new )

health checks with message on healthy state

here the call method gets an argument which allows to create both healthy and unhealthy states with message.

registry.register( 'app.block') do
  if app.crashed
    unhealthy( 'application crashed' )
  else
    healthy( 'application ok' )
  end
end

or with a health-check object

class AppCheck < Leafy::Health::HealthCheck
  def call
    if app.crashed
      unhealthy( 'application crashed' )
    else
      healthy( 'application ok' )
    end
  end
end
registry.register( 'app.class', AppCheck.new )

health checks with structural data as message

registry.register( 'app.block') do
  if app.crashed
    unhealthy( :host => 'localhost', :msg => 'not good' )
  else
    healthy( :host => 'localhost', :msg => 'application ok' )
  end
end

or as health-check object

class AppCheck < Leafy::Health::HealthCheck
  def call
    if app.crashed
      unhealthy( :host => 'localhost', :msg => 'application crashed' )
    else
      healthy( :host => 'localhost', :msg => 'application ok' )
    end
  end
end
registry.register( 'app.class', AppCheck.new )

unregister health checks

registry.unregister( 'app.class' )

builtin ThreadDeadlockHeathCheck

registry.register( 'app.deadlock', Leafy::Health::ThreadDeadlockHeathCheck.new )

note

currently there is not further introspection on the registry and its health-check. with the Leafy::Json::HealthWriter (from leafy-rack) you can get a json representation of the current health report

Leafy::Json::HealthWriter.to_json( registry.health )

developement

get all the gems and jars in place

gem install jar-dependencies --development
bundle install

for running all specs

rake

or

rspec spec/reporter_spec.rb