We’ve been using God to monitor our Thin processes on Freebootr and set it up to notify us through our Google Apps account. Thought our God config file might be useful to anyone trying to use God with Thin and Google Apps.

Thin configuration

# == God config file
# http://god.rubyforge.org/
# Authors: Gump and michael@glauche.de
#
# Config file for god that configures watches for each instance of a thin server for
# each thin configuration file found in /etc/thin.
# In order to get it working on Ubuntu, I had to make a change to god as noted at
# the following blog:
# http://blog.alexgirard.com/2007/10/25/ruby-one-line-to-save-god/
#
require 'yaml'
config_path = "/etc/thin"

Dir[config_path + "/*.yml"].each do |file|
  config = YAML.load_file(file)
  num_servers = config["servers"] ||= 1

  (0...num_servers).each do |i|
    # UNIX socket cluster use number 0 to 2 (for 3 servers)
    # and tcp cluster use port number 3000 to 3002.
    number = config['socket'] ? i : (config['port'] + i)

    God.watch do |w|
      w.group = "thin-" + File.basename(file, ".yml")
      w.name = w.group + "-#{number}"

      w.interval = 30.seconds

      w.uid = config["user"]
      w.gid = config["group"]

      w.start = "thin start -C #{file} -o #{number}"
      w.start_grace = 10.seconds

      w.stop = "thin stop -C #{file} -o #{number}"
      w.stop_grace = 10.seconds

      w.restart = "thin restart -C #{file} -o #{number}"

      pid_path = config["pid"]
      ext = File.extname(pid_path)

      w.pid_file = pid_path.gsub(/#{ext}$/, ".#{number}#{ext}")

      w.behavior(:clean_pid_file)

      w.start_if do |start|
        start.condition(:process_running) do |c|
          c.interval = 5.seconds
          c.running  = false
          c.notify   = 'developers'
        end
      end

      w.restart_if do |restart|
        restart.condition(:memory_usage) do |c|
          c.above  = 150.megabytes
          c.times  = [3,5] # 3 out of 5 intervals
          c.notify = 'developers'
        end

        restart.condition(:cpu_usage) do |c|
          c.above  = 50.percent
          c.times  = 5
          c.notify = 'developers'
        end
      end

      w.lifecycle do |on|
        on.condition(:flapping) do |c|
          c.to_state     = [:start, :restart]
          c.times        = 5
          c.within       = 5.minutes
          c.transition   = :unmonitored
          c.retry_in     = 10.minutes
          c.retry_times  = 5
          c.retry_within = 2.hours
          c.notify       = 'developers'
        end
      end

      w.transition(:up, :start) do |on|
        on.condition(:process_exits) do |c|
          c.notify = 'developers'
        end
      end
    end
  end
end

Email through Google Apps configuration

require 'tlsmail'
Net::SMTP.enable_tls(OpenSSL::SSL::VERIFY_NONE)

God::Contacts::Email.message_settings = {
  :from => 'user@domain.com'
}

God::Contacts::Email.server_settings = {
  :address        => 'smtp.gmail.com',
  :tls            => 'true',
  :port           => 587,
  :domain         => 'domain.com',
  :user_name      => 'user@domain.com',
  :password       => '******',
  :authentication => :plain
}

God.contact(:email) do |c|
  c.name  = 'Dev 1'
  c.email = 'dev1@domain.com'
  c.group = 'developers'
end

God.contact(:email) do |c|
  c.name  = 'Dev 2'
  c.email = 'dev2@domain.com'
  c.group = 'developers'
end

References

• God
• A Thin God
• A Gmail God

More of my rantings

• Google Maps API with large data sets
• Testing a helper with a block
• Quick Tip: Setting an SPF record

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• Export Excel Data to Google Maps!  (Tomas Carrillo)
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• Routing with the new Google Maps Data  (Maploser)

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