Hackatron

This is a guest post by Matteo Depalo from the Responsa team.

Introduction

This is a summary of my experiences and a mini-guide regarding the deploying and usage of a Cube server and Geckoboard to track statistics at Responsa.

I’ll explain how I deployed Cube to a VPS in the cloud and how I’ve integrated it in Responsa. I’ll also talk about Geckoboard and how we used it to draw graphs based on metrics extracted from Cube, but first here’s a brief description of Cube and Geckoboard.

Cube

Cube is a system for collecting timestamped events and deriving metrics. By collecting events rather than metrics, Cube lets you compute aggregate statistics post hoc. It also enables richer analysis, such as quantiles and histograms of arbitrary event sets.

Geckoboard

Geckoboard is a service for drawing graphs and statistics and organizing them in widgets that populate dashboards.

Deploying

To deploy the Cube server I’ve chosen Linode, a service that gives you an empty Ubuntu Server virtual machine in the cloud. After the creation of the machine you can just ssh inside and start installing your server.

To make the deploying process automatic I’ve chosen chef, and in particular chef-solo.

Since chef uses ruby we need to install it first in our machine so just run these commands to get some basic stuff:

# git and curl
apt-get -y update
apt-get -y install curl git-core python-software-properties

# ruby
curl -L https://raw.github.com/fesplugas/rbenv-installer/master/bin/rbenv-installer | bash
vim ~/.bashrc # add rbenv to the top
. ~/.bashrc
rbenv bootstrap-ubuntu-10-04
rbenv install 1.9.3-p125
rbenv global 1.9.3-p125
gem install bundler --no-ri --no-rdoc
rbenv rehash

Then you can install Cube with:

git clone git://github.com/matteodepalo/cube.git
cd cube

Now all you need to do is to download the cookbooks and run chef:

gem install librarian
librarian-chef install
chef-solo -c solo.rb

And your Cube server should be up and running ready to track events!

Tracking events

We use Ruby on Rails as our stack so I’ve chosen the cube-ruby gem to communicate with the server. With this gem you can talk with the Cube collector in order to track events.

For example if we want to track a request we can write:

$cube = Cube::Client.new 'your-host.com'
$cube.send "request", :value => 'somevalue'

Analysis

To compute metrics I’ve created a ruby gem called cube-evaluator, which talks with the Cube evaluator.

Let’s say we want the daily requests on our website in this month we can write:

$cube_evaluator = Cube::Evaluator.new 'your-host.com'
daily_requests = $cube_evaluator.metric(
				   :expression => 'sum(request)',
				   :start => 1.month.ago,
				   :stop => Time.now,
				   :step => '1day'
				 )

daily_requests will be an Hash containing the array of times and the array of corresponding values

Drawing

Geckoboard needs an endpoint in your server to poll in order to draw the data. To ease the creation of these endpoints I’ve improved and used the chameleon gem. Just add it to your gemfile

gem 'chameleon', :git => 'git://github.com/matteodepalo/chameleon.git'

then run bundle to install it

bundle install

Let’s draw the daily_requests now. Create a line widget graph

rails g chameleon:widget requests line

and use your daily_requests hash to populate it

Chameleon::Widget.new :requests do
  key "3618c90ec02d5a57061ad7b78afcbb050e50b608"
  type "line"
  data do
    {
      :items => daily_requests[:values],
      :x_axis => daily_requests[:times],
      :y_axis => [daily_requests[:times].min, daily_requests[:times].max]
    }
  end
end

Congrats! You are now tracking statistics in the coolest way possible ;)