Monitoring our applications - Ruby - Overview

by Marc Watts

A target of ours has been to improve the monitoring of our applications. I'm sure this is true for nearly all Software companies. We have applications written in various languages, the main "must-monitor" ones in Ruby and Java. This article explains how we implemented statsd into our Ruby applications.

Requirements:

Simple to setup
Clean implementation
Easy to change
Open source (bonus)

We started with the quick and simple reinh statsd implementation, but quickly found we wanted more functionality, such as:

Automatically prefix the application name for the statistic being sent
Automatically prefix the server name for the statistic being sent
Automatically prefix the environment name for the statistic being sent
Configure via YAML file and Ruby code
Less inline code interference

At this point Fozzie was born. Fozzie rapidly grew in functionality as we learnt what we wanted to measure in our Ruby and Ruby on Rails applications. The simplicity of statsd allowed us to really extend what we wanted to measure, and also abstract the amount of code needed to achieve this.

YAML Based Configuration

Fozzie settings can be customised via a fozzie.yml file, located at config/ on your application root.

You can set the host, port, appname, and namespaces for your application.

Namespaces are the class calls you want to use in your code to register statistics. The defaults are:

Stats.increment 'wat
S.increment 'wat'
Statistics.increment 'wat
Warehouse.increment 'wat'

Ruby Code Monitoring

To monitor some Ruby code Fozzie provided namespace to register your stats against, such as:

S.increment 'wat'
S.decrement 'wat'
S.time_for 'wat' { sleep 5 }
S.timing, 'wat', 500
S.time_to_do { sleep 5 }

Rack Middleware

Fozzie allows Rack developers to measure their controller action methods with minimum effort.

require 'rack'
require 'fozzie'
app = Rack::Builder.new { use Fozzie::Rack::Middleware lambda { |env| [200, {'Content-Type' =&gt; 'text/plain'}, 'OK'] } }

Rails Middleware

Base upon the Rack middleware, Fozzie can provide statistics of the Rails controller action timings. If Fozzie is added to the Rails application Gemfile, the Fozzie Railtie will automatically load the Rails Middleware into the application stack on application initialization.

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