Extendable Metal Redirects

.gitignore

.DS_Store

special_redirects.rb

# Some code and ideas borrowed from https://github.com/p8/redirect
# Add this to the metal folder in a Rails project

# Allow the metal piece to run in isolation
require(File.dirname(__FILE__) + "/../../config/environment") unless defined?(Rails)

class SpecialRedirects
  
  def self.our_redirects
    # example of setting a temp redirect (or other server response code)
    [ 
      # ['/test', 'http://www.test.com', {:code => 302}]
      # [/\/speaker(\S*)/, "http://speaker.something.com$1"]
      # ["http://www.something.com/learn-whatever", "http://www.something.com/Learn-Whatever"]     
    ]
  end
  
  def self.fullurl(env)
    "http://#{env['SERVER_NAME']}#{env['PATH_INFO']}".downcase
  end
  
  class RData
    attr_reader :catch_url, :redirect_url, :code, :content_type
    def initialize(catch_url, redirect_url, options = {})
      @catch_url = catch_url
      @redirect_url = redirect_url
      @code = options[:code] || default_code
      @content_type = options[:content_type] || "text/html"
    end

    def default_code
      301
    end
    
  end
  
  def self.call(env)

    @redirects ||= our_redirects.collect do |r| 
      RData.new(*r)
    end
    
    @redirects.each do |r|
      
      if fullurl(env).match(r.catch_url)
        redirect_url = r.redirect_url
        if $1
          redirect_url.gsub!('$1', $1)
        end
        return [r.code, {"Location" => redirect_url, "Content-Type" => r.content_type}, "Redirecting to: #{redirect_url}"]
      end
    end
  
    [404, {"Content-Type" => "text/html"}, ["Not Found"]]
  end

end

This code could be further extended by storing the array as a set in Redis etc. which would permit redirects to be added without code changes. For us, as of this writing, that was a YAGNI issue.