Heroku Rolling Restarts

heroku_maintenance.rb

class HerokuMaintenance

    def self.rolling_restarts
      puts "Processing Rolling Restarts"
      processes = time_hash[Time.now.hour]
      if processes
        puts "restarting: #{processes.inspect}"
        processes.each { |process| restart_process(process) if process}
      else
        puts "No restarts scheduled for hour: [#{Time.now.hour}]"
      end

    end

    def self.restart_process(name)
      puts "restarting process #{name}:"
      heroku_client.ps_restart(ENV['APP_NAME'], :ps => name)
    end

    def self.time_hash

      heroku_ps = heroku_client.ps(ENV['APP_NAME'])

      number_of_web_dynos = heroku_ps.select{|h| h['process'] =~ /^web\./}.count

      dyno_ids = []
      # doing it twice to rotate twice a day
      dyno_ids << (1..number_of_web_dynos).to_a
      dyno_ids << (1..number_of_web_dynos).to_a
      dyno_ids.flatten!

      hours_to_run = [1,3,5,7,15,17,20,22,0]

      grouped_dynos = dyno_ids.in_groups_of(hours_to_run.length).transpose

      t_hash = {}
      hours_to_run.each_with_index do |h,i|
        t_hash[h] = numbers_to_process_array(grouped_dynos[i])
      end

      t_hash
    end

    def self.numbers_to_process_array(array_of_nums)
      process_array = []
      array_of_nums.each{|n| process_array << "web.#{n}"}
      process_array
    end

    def self.heroku_client
      Heroku::Client.new(ENV['APP_USERNAME'], ENV['APP_PASSWORD'])
    end


  end