Rake task to migrate an application from bamboo stack do cedar stack on Heroku

heroku_migrate_from_bamboo_to_cedar.rake

# -*- encoding : utf-8 -*-

# Rafael Lima (http://rafael.adm.br)
# License: http://creativecommons.org/licenses/by/2.5/
#
# ATTENTION: This is a initial work, use it at your own risk!
#
# Usage:
# $ APP_NAME=myappname rake heroku:migrate_from_bamboo_to_cedar

namespace :heroku do
  def run(*cmd)
    system(*cmd)
    raise "Command #{cmd.inspect} failed!" unless $?.success?
  end

  def confirm(message, abort=true)
    print "\n#{message}\nAre you sure? [yN] "
    confirmed = STDIN.gets.chomp.downcase == 'y'
    raise 'Aborted' if abort and !confirmed
    confirmed
  end

  def step(message)
    return unless confirm(message, false)
    print "-----> #{message}…"
    yield
    puts " OK"
  end

  task :migrate_from_bamboo_to_cedar => :environment do
    current_app = ENV['APP_NAME']
    raise "You must set environment variable APP_NAME. Try running: APP_NAME=myappname rake heroku:migrate_from_bamboo_to_cedar" if ENV['APP_NAME'].nil?
    new_app = "#{current_app}-new"
    old_app = "#{current_app}-old"

    step "Checking current stack" do
      ret = `heroku stack --app #{current_app} |grep '*'`
      stack = ret.strip.gsub("* ", "")
      raise "Current application should be running on bamboo-mri-1.9.2 to be migrated but it ir running on #{stack}. More info at: http://devcenter.heroku.com/articles/cedar#migrating_from_bamboo_to_cedar" if stack != "bamboo-mri-1.9.2"
    end

    step "Checking log configuration" do
      ret = `heroku config -s --app #{current_app} |grep RACK_ENV`
      env = ret.strip.split("=")[1]
      file_name = Rails.root.join('config','environments',"#{env}.rb")
      raise "Environment file (#{file_name}) not found" unless File.exists?(file_name)
      ret = `cat #{file_name} |grep config.logger`
      lines = ret.split("\n")
      ocurrences = lines.map do |line|
        line.strip[0] != "#"
      end
      raise "Environment file (#{file_name}) should not have config.logger directive. More info at: https://github.com/ddollar/rails_log_stdout/issues/4#issuecomment-2512778" if ocurrences.include?(true)
    end

    step "Checking mailer configuration" do
      ret = `heroku addons --app #{current_app} |grep sendgrid`
      if !ret.strip.blank?
        ret = `heroku config -s --app #{current_app} |grep RACK_ENV`
        env = ret.strip.split("=")[1]
        file_name = Rails.root.join('config','environments',"#{env}.rb")
        raise "Environment file (#{file_name}) not found" unless File.exists?(file_name)
        ret = `cat #{file_name} |grep config.action_mailer.smtp_settings`
        lines = ret.split("\n")
        ocurrences = lines.map do |line|
          line.strip[0] != "#"
        end
        raise "You have sendgrid addon and the environment file (#{file_name}) don't have the configuration of action_mailer. More info at: http://devcenter.heroku.com/articles/sendgrid#usage" if ocurrences.empty? or !ocurrences.include?(true)
      end
    end

    step "Checking SSL" do
      ret = `heroku ssl --app #{current_app} |grep 'SSL certificate registered'`
      if ret.strip != ""
        domain = /(.*)\shas a SSL certificate registered/.match(ret.strip)[1]
        confirm("As you have SSL, you will have to change the CNAME value for the domain #{domain} and your application will be offline for a while until DNS propagate.")
        pem_file_name = Rails.root.join("config/certs/#{domain}.pem")
        key_file_name = Rails.root.join("config/certs/#{domain}.key")
        raise "Current application has SSL certificate, you will need the PEM file at #{pem_file_name} to finish the upgrade." unless File.exists?(pem_file_name)
        raise "Current application has SSL certificate, you will need the KEY file at #{key_file_name} to finish the upgrade." unless File.exists?(key_file_name)
      end
    end

    step "Looking for Procfile" do
      raise "This project doesn't have Procfile. Read more at: http://devcenter.heroku.com/articles/rails3#webserver" unless File.exists?(Rails.root.join("Procfile"))
      ret = `git blame Procfile`
      raise "Procfile is not commited" unless ret.strip != "fatal: cannot stat path 'Procfile': No such file or directory"
    end

    step "Creating #{new_app}" do
      ret = `heroku apps |grep #{new_app}`
      if ret.strip != "#{new_app}"
        run("heroku create #{new_app} --stack cedar")
      end
    end

    step "Installing addons" do
      ret = `heroku addons --app #{current_app}`
      current_addons = ret.split("\n").map do |e| e.split(" => ")[0] end
      ret = `heroku addons --app #{new_app}`
      new_addons = ret.split("\n").map do |e| e.split(" => ")[0] end
      addons_to_install = current_addons - new_addons
      print " #{addons_to_install.inspect}"
      addons_to_install.each do |addon|
        puts "ATTENTION: Addon #{addon} is deprecated and need to be replaced!" if ["cron:hourly", "ssl:hostname"].include?(addon)
        if ["logging:expanded"].include?(addon)
          `heroku addons:upgrade #{addon} --app #{new_app}`
        else
          `heroku addons:add #{addon} --app #{new_app}`
        end
      end
    end

    step "Promoting database" do
      print "Wait for database to be created. What is the code of database (Ex: HEROKU_POSTGRESQL_RED)?"
      database_code = STDIN.gets.chomp.strip.upcase
      run "heroku pg:promote #{database_code} --app #{new_app}"
    end

    # Only copy variables wich does not exists in new app
    step "Copying environment variables" do
      ret = `heroku config -s --app #{current_app}`
      current_vars = ret.split("\n")
      current_pairs = {}
      current_keys = []
      current_vars.each do |var|
        key = var.split("=")[0]
        value = var.split("=")[1]
        current_pairs[key] = value
        current_keys << key
      end
      ret = `heroku config -s --app #{new_app}`
      new_vars = ret.split("\n")
      new_pairs = {}
      new_keys = []
      new_vars.each do |var|
        key = var.split("=")[0]
        value = var.split("=")[1]
        new_pairs[key] = value
        new_keys << key
      end
      configs_to_add = current_keys - new_keys
      print " #{configs_to_add.inspect}"
      configs = []
      configs_to_add.each do |config|
        configs << %{#{config}="#{current_pairs[config]}"}
      end
      if !configs.empty?
        `heroku config:add #{configs.join(' ')} --app #{new_app}`
      end
    end
    
    step "Set RACK_ENV and RAILS_ENV config vars" do
      ret = `heroku config -s --app #{current_app} |grep RACK_ENV`
      env = ret.strip.split("=")[1]
      run("heroku config:add RACK_ENV=#{env} RAILS_ENV=#{env} --app #{new_app}")
    end

    step "Pushing application to the new stack" do
      run "git push git@heroku.com:#{new_app}.git HEAD:master -f"
    end

    step "Setting Dynos" do
      ret = `heroku dynos --app #{current_app}`
      dynos = /.* is running (\d*) dyno/.match(ret.strip)[1].to_i
      if dynos > 1
        run("heroku scale web=#{dynos} --app #{new_app}")
      end
    end

    step "Setting Workers" do
      ret = `heroku workers --app #{current_app}`
      workers = /.* is running (\d*) worker/.match(ret.strip)[1].to_i
      if workers > 0
        run("heroku scale worker=#{workers} --app #{new_app}")
      end
    end

    step "Putting current application in maintenance mode" do
      run "heroku maintenance:on --app #{current_app}"
    end

    step "Copying database between applications" do
      run("heroku pgbackups:capture --app #{current_app} --expire")
      run("heroku pgbackups:restore DATABASE `heroku pgbackups:url --app #{current_app}` --app #{new_app} --confirm #{new_app}")
      run("heroku run rake db:migrate --app #{new_app}")
      run("heroku restart --app #{new_app}")
    end

    step "Copying domains between applications" do
      ret = `heroku ssl --app #{current_app} |grep 'SSL certificate registered'`
      if ret.strip != ""
        ssl_domain = /(.*)\shas a SSL certificate registered/.match(ret.strip)[1]
      else
        ssl_domain = nil
      end
      ret = `heroku domains --app #{current_app}`
      domains = ret.split("\n")
      domains.shift
      run("heroku config:add DOMAINS=#{domains.to_json} --app #{new_app}") # just to backup
      domains.each do |domain|
        run("heroku domains:remove #{domain} --app #{current_app}")
        run("heroku domains:add #{domain} --app #{new_app}")
      end
      if ssl_domain
        pem_file_name = Rails.root.join("config/certs/#{ssl_domain}.pem")
        key_file_name = Rails.root.join("config/certs/#{ssl_domain}.key")
        run("heroku ssl:add #{pem_file_name} #{key_file_name} --app #{new_app}")
      end
    end

    step "Rename applications" do
      run("heroku rename #{old_app} --app #{current_app}")
      run("heroku rename #{current_app} --app #{new_app}")
    end

    step "Restarting new application" do
      run("heroku restart --app #{current_app}")
    end

    puts "Adjust repositories in your .git/config"
  end
end