sinatra extension to forward linkerd headers with activeresource requests

linkerd.rb

require 'sinatra/extension'
require 'active_resource'

module L5D
  extend Sinatra::Extension

  class << self
    attr_accessor :headers
  end

  before do
    L5D.headers = {}
    request.env.each do |key, value|
      if key =~ /^HTTP_(L5D_CTX.*)$/
        header = $1.split('_').map(&:capitalize).join("-")
        L5D.headers[header] = value
      end
    end
  end
end

register L5D

module ActiveResource
  class Base
    cattr_accessor :static_headers
    self.static_headers = self.headers

    def self.headers
      static_headers.merge(L5D.headers)
    end
  end
end