Class: ScoutAgent::Assignment::Start

Inherits:
ScoutAgent::Assignment show all
Defined in:
lib/scout_agent/assignment/start.rb

Overview

Invoke with:

sudo scout_agent start

This command starts the Scout agent, if it is not already running.

The agent requires super user privileges to prepare it’s environment, but it will relenquish these privileges before it begins normal work.

The agent daemonizes itself as part of the startup process (unless configured not to) and thus will detach from your terminal. It will still be running happily in the background. You can check up on it with the status command, if you like.

Instance Attribute Summary

Attributes inherited from ScoutAgent::Assignment

#group, #other_args, #switches, #user

Instance Method Summary collapse

Methods inherited from ScoutAgent::Assignment

choose_group, choose_user, #initialize, plan, #prepare_and_execute

Methods included from Tracked

#clear_status, #force_status_database_reload, #status, #status_database, #status_log

Constructor Details

This class inherits a constructor from ScoutAgent::Assignment

Instance Method Details

#execute ⇒ Object

Runs the start command.



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# File 'lib/scout_agent/assignment/start.rb', line 26

def execute
  # build the directory for PID file storage, if needed
  unless Plan.pid_dir.exist?
    unless Plan.build_pid_dir(group.gid)
      abort_with_missing_pid_dir
    end
  end
  
  # switch to the selected user and group
  unless switch_group_and_user
    abort_with_wrong_group_or_user
  end
  
  # test our ability to reach the server
  unless test_server_connection(:quiet)
    abort_with_cannot_connect
  end
  
  # make a final check to see if everything looks properly prepared
  unless Plan.valid?            and
         Plan.pid_dir.exist?    and
         Plan.pid_dir.readable? and
         Plan.pid_dir.writable?
    abort_with_missing_resources
  end
  
  # make sure we are the only process running and daemonize, if configured
  running_mode = Plan.run_as_daemon? ? " as a daemon" : ""
  puts "Starting #{ScoutAgent.proper_agent_name}#{running_mode}..."
  card = IDCard.new(:lifeline)
  unless card.authorize { not Plan.run_as_daemon? or daemonize }
    other_process = card.pid
    if other_process and other_process != Process.pid
      abort_with_other_process_running(other_process)
    else
      abort_with_failure_to_daemonize
    end
  end
  
  # prepare the log
  log = ScoutAgent.prepare_wire_tap(:lifeline)
  log.info("Loading monitors.")
  
  # load configured agents
  agents = %w[master]
  agents << "communication" if Plan.enable_xmpp?
  
  # start each agent through a Lifeline monitor
  lifelines = agents.map { |agent| Lifeline.new(agent, log) }
  %w[TERM INT].each do |signal|
    trap(signal) do
      lifelines.each { |line| line.terminate }
    end
  end
  lifelines.each do |line|
    line.launch_and_monitor
  end
  
  # wait for all monitors to finish
  lifelines.each do |line|
    line.join
  end
  # wait for all children to obey our stop command
  Process.waitall
end