git push = deploy

github-receiver.rb

require 'rubygems'
require 'sinatra'
require 'yajl/json_gem'

post '/' do
  @push =  Yajl::Parser.new(:symbolize_keys => true).parse(params[:payload])
  appdir="/home/blackflag/app"
  @output= Kernel.system("cd #{appdir}/shared/cached-copy && git pull origin master && cap deploy")
  puts "\n output = #{@output} \n"
  puts "I got some JSON: #{@push.inspect}"
  'ok'
end