This is a Ruby version of performance metrics inspired by metrics developed by Coda Hale at Yammer. Currently this is under heavy development -- it needs Gem packaging, more features, validation of metrics, more functional testing, and a little better test coverage. Pull requests happily accepted, please include docs and tests where possible!

Among other important things, this needs to be made more thread-safe. I'm currently looking at Mr. Nutter's ruby-atomic gem for making this less tedious but any suggestions are welcome!

Right now, I have:

• Counters
• Meters
• Gauges
• Histograms w/ uniform sampling
• Histograms w/ exponentially decaying sampling
• Timers

The goal of ruby-metrics is to get up and running quickly. You start an agent, register some instruments, and they're exported over HTTP via JSON. For example, getting started with a counter would look like this:

@metrics = Metrics::Agent.new

counter = @metrics.counter :my_counter
counter.incr
counter.incr

puts @metrics.to_json
#=> {"my_counter":"2"}

Integrating ruby-metrics into existing applications is entirely up to your needs. Provided options include:

• Embedded WEBrick listener:

  This runs a background thread and enables HTTP access to a local port (8001 by default) for a JSON representation of the current metrics.

require 'ruby-metrics/integration/webrick'
@agent = Metrics::Agent.new
@agent.start(:port => 8081)

• Rack Middleware:

  This will add metrics such as requests (a timer) as well as counters for each class of HTTP status code (1xx, 2xx, etc). Also counts uncaught exceptions before reraising. Provides a configurable path option (:show) to trigger the return of the metrics (as JSON) when the request path matches exactly (a string), as a regular expression, or as any object that responds to call for custom logic (passed the whole env).

require 'ruby-metrics'
@agent = Metrics::Agent.new

use Metrics::Integration::Rack::Middleware, :agent => @agent, :show => '/stats'

run app

• Rack Endpoint:

  Use this to expose an endpoint for external consumption for your metrics. Works best when used with a URLMap or mounted in addition to other routes, like Rails' mount route matcher.

require 'ruby-metrics'
@agent = Metrics::Agent.new

run Metrics::Integration::Rack::Endpoint.new(:agent => @agent)

or

# in config/router.rb
mount Metrics::Integration::Rack::Endpoint.new(:agent => @agent)

Copyright 2011-2014 John Ewart john@johnewart.net. Released under the MIT license. See the file LICENSE for further details.