Simple Pow Ruby process manager

powr.rb

#!/usr/bin/env ruby

# == Dependencies ===========================================================

require 'optparse'
require 'open3'

# == Constants ==============================================================

PATH_LENGTH_MAX = 255
ROOT_TRIGGER = 'config.ru'.freeze
RESTART_PATH = 'tmp/restart.txt'.freeze

# == Support Methods ========================================================

def rails_processes(path)
  ps, status = Open3.capture2("ps", "aux")
  path_rx = Regexp.new(Regexp.escape(path))

  return [ ] unless (ps)

  ps.split(/\n/).collect do |line|
    parts = line.split(/\s+/)

    # Ignore header. Should work with default OS X and Linux `ps` tool.
    next if (parts[0] == 'USER')

    [ parts[1].to_i, parts[10, parts.length] ]
  end.select do |process|
    process and process[1].grep(path_rx).any?
  end
end

def rails_root
  return @rails_root unless (@rails_root.nil?)

  @rails_root = false
  path = Dir.pwd

  while (File.exists?(path) and (path.length < PATH_LENGTH_MAX) and !@rails_root)
    if (File.exists?(File.expand_path(ROOT_TRIGGER, path)))
      @rails_root = path
    else
      last_path = path
      path = File.expand_path("..", path)

      break if (last_path == path)
    end
  end

  @rails_root
end

# == Main ===================================================================

options = { }

parser = OptionParser.new do |parser|
  parser.on("-s", "--show", "List all Pow launched Ruby processes") do
    options[:show] = true
  end
  parser.on("-k", "--kill", "Kill all Pow launched Ruby processes") do
    options[:kill] = true
  end
  parser.on("-t", "--touch", "Creates a new #{RESTART_PATH} in the Rails root (default action)") do
    options[:touch] = true
  end
end

args = parser.parse(*ARGV)

_root = rails_root

unless (_root)
  STDERR.puts("Could not find #{ROOT_TRIGGER} to locate Rails root")
  exit(-1)
end

if (options[:show])
  rails_processes(_root).each do |process|
    puts '%6d %s' % [ process[0], process[1].join(' ') ]
  end
elsif (options[:kill])
  rails_processes(_root).each do |process|
    Process.kill('TERM', process[0])
  end
else
  system("touch", File.expand_path(RESTART_PATH, _root))
end