Simple Github Hook Receiver

webhook.rb

require 'sinatra'
require 'json'

get '/' do
end

post '/payload' do
  request.body.rewind
  
  payload_body = request.body.read
  verify_signature(payload_body)

  json = JSON.parse(payload_body)
  ssh_url = json["repository"]["ssh_url"]
  name = json["repository"]["name"]

  if Dir.exists?(name)
  	puts "Update #{ssh_url}"
  	`cd #{name} && git pull origin master`
  else
  	puts "Clone #{ssh_url}"
  	`git clone #{ssh_url}`
  end
  
  `cd #{name} && ./scripts/setup && ./scripts/start`
end

def verify_signature(payload_body)
  signature = 'sha1=' + OpenSSL::HMAC.hexdigest(OpenSSL::Digest.new('sha1'), ENV['SECRET_TOKEN'], payload_body)
  puts signature
  return halt 500, "Signatures didn't match!" unless Rack::Utils.secure_compare(signature, request.env['HTTP_X_HUB_SIGNATURE'])
end