Updated script for updating psych. lul.

upgrade_ruby_pysch.rb

require 'json'

class Shell
  def self.heroku_apps
    new('heroku apps').cache_at 'heroku_app_cache'
  end

  def self.ruby_version app
    new("heroku run \"ruby -v\" --app #{app}").cache_at "ruby_version_#{app}"
  end

  def self.yaml_version app
    new("heroku run \"ruby -r yaml -e 'puts Psych::LIBYAML_VERSION'\" --app #{app}").cache_at "yaml_version_#{app}"
  end

  def self.psych_version app
    new("heroku run \"ruby -rpsych -e 'p Psych.libyaml_version.join(%q%.%)'\" --app #{app}").cache_at "psych_version_#{app}"
  end

  def initialize cmd
    @cmd = cmd
  end

  def cache_at key
    from_key(key) || cache(key,from_cmd)
  end

private

  def json
    @json ||=
      begin
        if File.exist?(file)
          JSON.parse(File.read file)
        else
          {}
        end
      end
  end

  def from_key name
    json[name]
  end

  def from_cmd
    `#{@cmd}`
  end

  def cache name, string
    json[name] = string
    write_cache
    string
  end

  def file
    './heroku_app_info.json'
  end

  def write_cache
    File.open(file,'w+') { |file| file.write JSON.dump json }
  end

end

class Heroku

  def self.apps
    new.apps
  end

  def self.ruby_version_for name
    new.ruby_version_for name
  end

  def self.yaml_version_for name
    new.yaml_version_for name
  end

  def self.psych_version_for name
    new.psych_version_for name
  end

  def apps
    lines_containing_apps strip_trailing_info parse(Shell.heroku_apps)
  end

  def ruby_version_for name
    RubyVersionString.new parse(Shell.ruby_version name).find { |line| line =~ /ruby\s+\d\.\d\.\d/ }
  end

  def yaml_version_for name
    parse(Shell.yaml_version name).find { |line| line =~ /\d+\.\d+\.\d+/ }
  end

  def psych_version_for name
    parse(Shell.psych_version name).find { |line| line =~ /\d+\.\d+\.\d+/ }
  end


private

  def parse string
    string.split("\n")
  end

  def strip_trailing_info lines
    lines.map { |app| app.gsub(/\s+.*/,'') }
  end

  def lines_containing_apps lines
    lines.select { |app| app =~ /^[\w-]+$/ }
  end

end

class NestedHash < Hash

  def initialize
    super { |hash, key| hash[key] = Hash.new }
  end

end

class RubyVersionString

  def initialize string
    @major, @patch = string.scan(/(\d\.\d\.\d)(?:-?p(\d\d\d))?/).first
  end
  attr_reader :major

  def patch
    @patch.to_i
  end

end

module Versions
  module_function

  def for provider
    provider.apps.inject(NestedHash.new) do |hash, app|
      version = provider.ruby_version_for app
      hash[version.major][app] = version.patch
      hash
    end
  end

end

ALLOWED_VERSIONS =
  {
    '1.9.3' => 484,
    '2.0.0' => 353,
  }

versions = Heroku.apps.map do |app|
  [app, Heroku.psych_version_for(app)]
end

to_upgrade = versions.select do |app, version|
  if version
    major, minor, patch = version.split('.').map &:to_i
    major <= 0 && minor <= 1 && patch < 6
  end
end

to_upgrade.each do |app, version|
  puts "App #{app} running old psych version #{version}"
  `heroku git:clone #{app} && cd #{app} && git ci -m "rebuild psych" --allow-empty && git push heroku master`
end