cluster.yml

name: AppName
port: 4020
environment: production
size: 3

merb-cluster.rb

#!/opt/local/bin/ruby

require "yaml"

module MerbCluster
  OPTIONS = {
    "environment" => "-e",
    "port"        => "-p",
    "name"        => "-n",
    "size"        => "-c"
  }
  
  def self.start
    config_path = File.join(Dir.pwd, "config", "cluster.yml")
    if File.exists?(config_path)
      config = YAML.load_file(config_path)
      args = OPTIONS.inject([]) do |memo, option|
        memo << "#{option[1]} #{config[option[0]]}" if config[option[0]]
        memo
      end
      puts `merb #{args.join(" ")}`
    else
      puts "Could not start cluster: cluster.yml is either missing, or you are not inside a merb application."
    end
  end
  
  def self.stop
    puts `merb -k`
  end
  
  def self.restart
    puts stop
    puts start
  end
  
  def self.fast_deploy
    puts `merb --fast-deploy`
  end
end

case ARGV[0]
  when "start"
    MerbCluster.start
  when "stop"
    MerbCluster.stop
  when 'restart'
    MerbCluster.restart
end