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God

Constants

DRB_ALLOW_DEFAULT

The default Array of String IPs that will allow DRb communication access.

DRB_PORT_DEFAULT

The default Integer port number for the DRb communcations channel.

LOG_BUFFER_SIZE_DEFAULT

The Integer number of lines of backlog to keep for the logger.

LOG_LEVEL_DEFAULT

The default Symbol log level.

PID_FILE_DIRECTORY_DEFAULTS

An Array of directory paths to be used as the default PID file directory. This list will be searched in order and the first one that has write permissions will be used.

STOP_SIGNAL_DEFAULT

The default String signal to send for the stop command.

STOP_TIMEOUT_DEFAULT

The default Integer number of seconds to wait for a process to terminate.

TERMINATE_TIMEOUT_DEFAULT

The default Integer number of seconds to wait for god to terminate when issued the quit command.

VERSION

The String version number for this package.

Attributes

contact_groups[RW]

internal

contacts[RW]

internal

groups[RW]

internal

inited[RW]

internal

main[RW]

internal

pending_watch_states[RW]

internal

pending_watches[RW]

internal

running[RW]

internal

server[RW]

internal

watches[RW]

internal

Public Class Methods

at_exit() click to toggle source

To be called on program exit to start god.

Returns nothing.

# File lib/god.rb, line 725
def self.at_exit
  self.start
  self.join
end
contact(kind) click to toggle source

Instantiate a new Contact of the given kind and send it to the block. Then prepare, validate, and record the Contact. Aborts on invalid kind, duplicate contact name, invalid contact, or conflicting group name.

kind - The Symbol contact class specifier.

Returns nothing.

# File lib/god.rb, line 367
def self.contact(kind)
  # Ensure internal init has run.
  self.internal_init

  # Verify contact has been loaded.
  if CONTACT_LOAD_SUCCESS[kind] == false
    applog(nil, :error, "A required dependency for the #{kind} contact is unavailable.")
    applog(nil, :error, "Run the following commands to install the dependencies:")
    CONTACT_DEPS[kind].each do |d|
      applog(nil, :error, "  [sudo] gem install #{d}")
    end
    abort
  end

  # Create the contact.
  begin
    c = Contact.generate(kind)
  rescue NoSuchContactError => e
    abort e.message
  end

  # Send to block so config can set attributes.
  yield(c) if block_given?

  # Call prepare on the contact.
  c.prepare

  # Remove existing contacts of same name.
  existing_contact = self.contacts[c.name]
  if self.running && existing_contact
    self.uncontact(existing_contact)
  end

  # Warn and noop if the contact has been defined before.
  if self.contacts[c.name] || self.contact_groups[c.name]
    applog(nil, :warn, "Contact name '#{c.name}' already used for a Contact or Contact Group")
    return
  end

  # Abort if the Contact is invalid, the Contact will have printed out its
  # own error messages by now.
  unless Contact.valid?(c) && c.valid?
    abort "Exiting on invalid contact"
  end

  # Add to list of contacts.
  self.contacts[c.name] = c

  # Add to contact group if specified.
  if c.group
    # Ensure group name hasn't been used for a contact already.
    if self.contacts[c.group]
      abort "Contact Group name '#{c.group}' already used for a Contact"
    end

    self.contact_groups[c.group] ||= []
    self.contact_groups[c.group] << c
  end
end
control(name, command) click to toggle source

Control the lifecycle of the given task(s).

name - The String name of a task/group. command - The String command to run. Valid commands are:

"start", "monitor", "restart", "stop", "unmonitor", "remove".

Returns an Array of String task names affected by the command.

# File lib/god.rb, line 446
def self.control(name, command)
  # Get the list of items.
  items = Array(self.watches[name] || self.groups[name]).dup

  jobs = []

  # Do the command.
  case command
    when "start", "monitor"
      items.each { |w| jobs << Thread.new { w.monitor if w.state != :up } }
    when "restart"
      items.each { |w| jobs << Thread.new { w.move(:restart) } }
    when "stop"
      items.each { |w| jobs << Thread.new { w.action(:stop); w.unmonitor if w.state != :unmonitored } }
    when "unmonitor"
      items.each { |w| jobs << Thread.new { w.unmonitor if w.state != :unmonitored } }
    when "remove"
      items.each { |w| self.unwatch(w) }
    else
      raise InvalidCommandError.new
  end

  jobs.each { |j| j.join }

  items.map { |x| x.name }
end
internal_init() click to toggle source

Initialize internal data.

Returns nothing.

# File lib/god.rb, line 232
def self.internal_init
  # Only do this once.
  return if self.inited

  # Variable init.
  self.watches = {}
  self.groups = {}
  self.pending_watches = []
  self.pending_watch_states = {}
  self.contacts = {}
  self.contact_groups = {}

  # Set defaults.
  self.log_buffer_size ||= LOG_BUFFER_SIZE_DEFAULT
  self.port ||= DRB_PORT_DEFAULT
  self.allow ||= DRB_ALLOW_DEFAULT
  self.log_level ||= LOG_LEVEL_DEFAULT
  self.terminate_timeout ||= TERMINATE_TIMEOUT_DEFAULT

  # Additional setup.
  self.setup

  # Log level.
  log_level_map = {:debug => Logger::DEBUG,
                   :info => Logger::INFO,
                   :warn => Logger::WARN,
                   :error => Logger::ERROR,
                   :fatal => Logger::FATAL}
  LOG.level = log_level_map[self.log_level]

  # Init has been executed.
  self.inited = true

  # Not yet running.
  self.running = false
end
join() click to toggle source

Prevent god from exiting.

Returns nothing.

# File lib/god.rb, line 713
def self.join
  self.main.join if self.main
end
load(glob) click to toggle source

Load the given file(s) according to the given glob.

glob - The glob-enabled String path to load.

Returns nothing.

# File lib/god.rb, line 631
def self.load(glob)
  Dir[glob].each do |f|
    Kernel.load f
  end
end
pattern_match(pattern, list) click to toggle source

Match a shortened pattern against a list of String candidates. The pattern is expanded into a regular expression by inserting .* between each character.

pattern - The String containing the abbreviation. list - The Array of Strings to match against.

Examples

list = %w{ foo bar bars }
pattern = 'br'
God.pattern_match(list, pattern)
# => ['bar', 'bars']

Returns the Array of matching name Strings.

# File lib/god.rb, line 747
def self.pattern_match(pattern, list)
  regex = pattern.split('').join('.*')

  list.select do |item|
    item =~ Regexp.new(regex)
  end.sort_by { |x| x.size }
end
registry() click to toggle source
# File lib/god/registry.rb, line 2
def self.registry
  @registry ||= Registry.new
end
running_load(code, filename, action = nil) click to toggle source

Load a config file into a running god instance. Rescues any exceptions that the config may raise and reports these back to the caller.

code - The String config file contents. filename - The filename of the config file. action - The optional String command specifying how to deal with

existing watches. Valid options are: 'stop', 'remove' or
'leave' (default).

Returns a three-tuple Array [loaded_names, errors, unloaded_names] where:

loaded_names   - The Array of String task names that were loaded.
errors         - The String of error messages produced during the
                 load phase. Will be a blank String if no errors
                 were encountered.
unloaded_names - The Array of String task names that were unloaded
                 from the system (if 'remove' or 'stop' was
                 specified as the action).
# File lib/god.rb, line 570
def self.running_load(code, filename, action = nil)
  errors = ""
  loaded_watches = []
  unloaded_watches = []
  jobs = []

  begin
    LOG.start_capture

    Gem.clear_paths
    eval(code, root_binding, filename)
    self.pending_watches.each do |w|
      if previous_state = self.pending_watch_states[w.name]
        w.monitor unless previous_state == :unmonitored
      else
        w.monitor if w.autostart?
      end
    end
    loaded_watches = self.pending_watches.map { |w| w.name }
    self.pending_watches.clear
    self.pending_watch_states.clear

    self.watches.each do |name, watch|
      next if loaded_watches.include?(name)

      case action
      when 'stop'
        jobs << Thread.new(watch) { |w| w.action(:stop); self.unwatch(w) }
        unloaded_watches << name
      when 'remove'
        jobs << Thread.new(watch) { |w| self.unwatch(w) }
        unloaded_watches << name
      when 'leave', '', nil
        # Do nothing
      else
        raise InvalidCommandError, "Unknown action: #{action}"
      end
    end

    # Make sure we quit capturing when we're done.
    LOG.finish_capture
  rescue Exception => e
    # Don't ever let running_load take down god.
    errors << LOG.finish_capture

    unless e.instance_of?(SystemExit)
      errors << e.message << "\n"
      errors << e.backtrace.join("\n")
    end
  end

  jobs.each { |t| t.join }

  [loaded_watches, errors, unloaded_watches]
end
running_log(watch_name, since) click to toggle source

Log lines for the given task since the specified time.

watch_name - The String name of the task (may be abbreviated). since - The Time since which to report log lines.

Raises God::NoSuchWatchError if no tasks matched. Returns the String of newline separated log lines.

# File lib/god.rb, line 543
def self.running_log(watch_name, since)
  matches = pattern_match(watch_name, self.watches.keys)

  unless matches.first
    raise NoSuchWatchError.new
  end

  LOG.watch_log_since(matches.first, since)
end
setup() click to toggle source

Setup pid file directory and log system.

Returns nothing.

# File lib/god.rb, line 640
def self.setup
  if self.pid_file_directory
    # Pid file dir was specified, ensure it is created and writable.
    unless File.exist?(self.pid_file_directory)
      begin
        FileUtils.mkdir_p(self.pid_file_directory)
      rescue Errno::EACCES => e
        abort "Failed to create pid file directory: #{e.message}"
      end
    end

    unless File.writable?(self.pid_file_directory)
      abort "The pid file directory (#{self.pid_file_directory}) is not writable by #{Etc.getlogin}"
    end
  else
    # No pid file dir specified, try defaults.
    PID_FILE_DIRECTORY_DEFAULTS.each do |idir|
      dir = File.expand_path(idir)
      begin
        FileUtils.mkdir_p(dir)
        if File.writable?(dir)
          self.pid_file_directory = dir
          break
        end
      rescue Errno::EACCES => e
      end
    end

    unless self.pid_file_directory
      dirs = PID_FILE_DIRECTORY_DEFAULTS.map { |x| File.expand_path(x) }
      abort "No pid file directory exists, could be created, or is writable at any of #{dirs.join(', ')}"
    end
  end

  if God::Logger.syslog
    LOG.info("Syslog enabled.")
  else
    LOG.info("Syslog disabled.")
  end

  applog(nil, :info, "Using pid file directory: #{self.pid_file_directory}")
end
signal(name, signal) click to toggle source

Send a signal to each task.

name - The String name of the task or group. signal - The String or integer signal to send. e.g. 'HUP', 9.

Returns an Array of String names of the tasks affected.

# File lib/god.rb, line 528
def self.signal(name, signal)
  items = Array(self.watches[name] || self.groups[name]).dup
  jobs = []
  items.each { |w| jobs << Thread.new { w.signal(signal) } }
  jobs.each { |j| j.join }
  items.map { |x| x.name }
end
start() click to toggle source

Initialize and startup the machinery that makes god work.

Returns nothing.

# File lib/god.rb, line 686
def self.start
  self.internal_init

  # Instantiate server.
  self.server = Socket.new(self.port, self.socket_user, self.socket_group, self.socket_perms)

  # Start monitoring any watches set to autostart.
  self.watches.values.each { |w| w.monitor if w.autostart? }

  # Clear pending watches.
  self.pending_watches.clear

  # Mark as running.
  self.running = true

  # Don't exit.
  self.main =
  Thread.new do
    loop do
      sleep 60
    end
  end
end
status() click to toggle source

Gather the status of each task.

Examples

God.status
# => { 'mongrel' => :up, 'nginx' => :up }

Returns a Hash where the key is the String task name and the value is the

Symbol status.
# File lib/god.rb, line 514
def self.status
  info = {}
  self.watches.map do |name, w|
    info[name] = {:state => w.state, :group => w.group}
  end
  info
end
stop_all() click to toggle source

Unmonitor and stop all tasks.

Returns true on success, false if all tasks could not be stopped within 10 seconds

# File lib/god.rb, line 477
def self.stop_all
  self.watches.sort.each do |name, w|
    Thread.new do
      w.unmonitor if w.state != :unmonitored
      w.action(:stop) if w.alive?
    end
  end

  terminate_timeout.times do
    return true unless self.watches.map { |name, w| w.alive? }.any?
    sleep 1
  end

  return false
end
task(klass = Task) click to toggle source

Instantiate a new, empty Task object and yield it to the mandatory block. The attributes of the task will be set by the configuration file. Aborts on duplicate task name, invalid task, or conflicting group name.

Returns nothing.

# File lib/god.rb, line 283
def self.task(klass = Task)
  # Ensure internal init has run.
  self.internal_init

  t = klass.new
  yield(t)

  # Do the post-configuration.
  t.prepare

  # If running, completely remove the watch (if necessary) to prepare for
  # the reload
  existing_watch = self.watches[t.name]
  if self.running && existing_watch
    self.pending_watch_states[existing_watch.name] = existing_watch.state
    self.unwatch(existing_watch)
  end

  # Ensure the new watch has a unique name.
  if self.watches[t.name] || self.groups[t.name]
    abort "Task name '#{t.name}' already used for a Task or Group"
  end

  # Ensure watch is internally valid.
  t.valid? || abort("Task '#{t.name}' is not valid (see above)")

  # Add to list of watches.
  self.watches[t.name] = t

  # Add to pending watches.
  self.pending_watches << t

  # Add to group if specified.
  if t.group
    # Ensure group name hasn't been used for a watch already.
    if self.watches[t.group]
      abort "Group name '#{t.group}' already used for a Task"
    end

    self.groups[t.group] ||= []
    self.groups[t.group] << t
  end

  # Register watch.
  t.register!

  # Log.
  if self.running && existing_watch
    applog(t, :info, "#{t.name} Reloaded config")
  elsif self.running
    applog(t, :info, "#{t.name} Loaded config")
  end
end
terminate() click to toggle source

Force the termination of god.

  • Clean up pid file if one exists

  • Stop DRb service

  • Hard exit using exit!

Never returns because the process will no longer exist!

# File lib/god.rb, line 499
def self.terminate
  FileUtils.rm_f(self.pid) if self.pid
  self.server.stop if self.server
  exit!(0)
end
uncontact(contact) click to toggle source

Remove the given contact from god.

contact - The Contact to remove.

Returns nothing.

# File lib/god.rb, line 432
def self.uncontact(contact)
  self.contacts.delete(contact.name)
  if contact.group
    self.contact_groups[contact.group].delete(contact)
  end
end
unwatch(watch) click to toggle source

Unmonitor and remove the given watch from god.

watch - The Watch to remove.

Returns nothing.

# File lib/god.rb, line 342
def self.unwatch(watch)
  # Unmonitor.
  watch.unmonitor unless watch.state == :unmonitored

  # Unregister.
  watch.unregister!

  # Remove from watches.
  self.watches.delete(watch.name)

  # Remove from groups.
  if watch.group
    self.groups[watch.group].delete(watch)
  end

  applog(watch, :info, "#{watch.name} unwatched")
end
version() click to toggle source

Returns the version String.

# File lib/god.rb, line 718
def self.version
  God::VERSION
end
watch(&block) click to toggle source

Instantiate a new, empty Watch object and pass it to the mandatory block. The attributes of the watch will be set by the configuration file. Aborts on duplicate watch name, invalid watch, or conflicting group name.

Returns nothing.

# File lib/god.rb, line 274
def self.watch(&block)
  self.task(Watch, &block)
end

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