+++
date = "2012-04-02"
title = "Showing Ruby, Rails and git info in your app"
tags = ["Ruby", "Rails", "protip"]
slug = "showing-ruby-rails-and-git-info-in-your-app"
+++
Some people've asked me how I show rendering information on [ariejan.net](http://ariejan.net).

![](https://ariejannet.s3.amazonaws.com/images/render_stats.jpg)

There are a few things going on here, let me explain them one by one.

### Rails version

The current Rails version is probably the easiest you see here. Rails exposes its version information like this:

    Rails.version

### Ruby version

Ruby also exposes version information, albeit using constants:

    RUBY_VERSION
    => "1.9.3"

You may know that ruby also has different patch levels for each release. You can also retrieve that information:

    RUBY_PATCHLEVEL
    => 125

The you may also want to know which engine you're using. This may be "ruby" or something different:

    RUBY_ENGINE
    => "ruby"

Combine these to get a sexy ruby version string:

    puts "#{RUBY_ENGINE}-#{RUBY_VERSION}-p#{RUBY_PATCHLEVEL}"
    => "ruby-1.9.3-p125"

### Current process ID

I like to know which Unicorn produced a certain page. Retrieving the process ID is easy:

    Process.pid
    => 9473

### Current git revision SHA

Knowing which version of your app is currently running can be useful information. To do this I created the following initializer:

    # config/initializers/git_revision.rb
    module AppName
      REVISION = `git log --pretty=format:'%h' -n 1`
    end

This will expose the current short SHA in your application's namespace:

    AppName::REVISION
    => "ac6d3a0"

You can now use this info through-out your app to show version information.