daemon.rb

#!/usr/bin/env ruby

require "rubygems"
require "pathname"
require "dante"
require "file-monitor"
require "mixlib/shellout"

module Dante
  class Runner
    protected

    def parse_options
      headline = [@name, @description].compact.join(" - ")

      OptionParser.new do |opts|
        opts.summary_width = 25

        opts.banner = [
          headline,
          "\n\n",
          "Usage: #{@name} [-P file] [-l file] [-d] [-k] [-f]\n",
          "       #{@name} --help\n"
        ].compact.join("")

        opts.separator ""

        opts.on("-d", "--daemon", "Daemonized mode") do |v|
          options[:daemonize] = v
        end

        opts.on("-k", "--kill", "Kill running daemon") do |v|
          options[:kill] = v
        end

        opts.on("-f", "--force", String, "Force kill if SIGTERM fails") do |v|
          options[:force] = true
        end

        opts.on("-P", "--pid FILE", String, "Save PID in FILE") do |v|
          options[:pid_path] = File.expand_path(v)
        end

        opts.on("-l", "--log FILE", String, "Logfile for output") do |v|
          options[:log_path] = v
        end

        opts.on("-u", "--user USER", String, "User to run as") do |user|
          options[:user] = user
        end

        opts.on("-G", "--group GROUP", String, "Group to run as") do |group|
          options[:group] = group
        end

        instance_exec(opts, &@with_options) if @with_options

        opts.separator ""

        opts.on_tail("-h", "--help", "Display this information") do
          puts [opts, "\n"].join
          exit
        end
      end.parse!

      options
    end
  end
end

module Webdev
  class Npm < FileMonitor
    def initialize(dir)
      super

      frequency 0.5
      follow_symlink true

      ignore_dirs /\.git$|\.svn$/

      filter_files {
        disallow /.*/
        allow /package\.json$/
      }
    end

    def check(events)
      begin
        path = nil

        events.each do |event|
          event.flags.each do |flag|
            if [:modify, :create].include? flag
              path = event.watcher.path
            end
          end
        end

        unless path.nil?
          cmd = command_in(
            path
          )

          puts "Running #{cmd.command.join(" ")} in #{path}"
          cmd.run_command
        end
      rescue => e
        puts "Error: #{e.message}"
      end
    end

    protected

    def command_in(dir)
      Mixlib::ShellOut.new(
        "npm",
        "install",
        :cwd => dir.to_s
      )
    end
  end
end

runner = Dante::Runner.new(
  "webdev-npm-runner",
  :pid_path => "/var/run/webdev/npm.pid", 
  :log_path => "/var/log/webdev/npm.log"
)

runner.description = "Webdev npm installation"

runner.with_options do |opts|
  opts.on("-D", "--directory PATH", String, "Directory to monitor") do |dir|
    options[:directory] = File.expand_path(dir)
  end
end

runner.verify_options_hook = lambda { |opts|
  opts[:directory] = "/vagrant" if opts[:directory].nil?
}

runner.execute do |options|
  monitor = Webdev::Npm.new options[:directory]
  monitor.run
end