lib/god.rb

   1 $:.unshift File.dirname(__FILE__)     # For use/testing when no gem is installed
   2
   3 require 'syslog'
   4
   5 # internal requires
   6 require 'god/errors'
   7
   8 require 'god/system/process'
   9
  10 require 'god/dependency_graph'
  11
  12 require 'god/behavior'
  13 require 'god/behaviors/clean_pid_file'
  14 require 'god/behaviors/notify_when_flapping'
  15
  16 require 'god/condition'
  17 require 'god/conditions/timeline'
  18 require 'god/conditions/process_running'
  19 require 'god/conditions/process_exits'
  20 require 'god/conditions/tries'
  21 require 'god/conditions/memory_usage'
  22 require 'god/conditions/cpu_usage'
  23 require 'god/conditions/always'
  24 require 'god/conditions/lambda'
  25 require 'god/conditions/degrading_lambda'
  26
  27 require 'god/reporter'
  28 require 'god/server'
  29 require 'god/timer'
  30 require 'god/hub'
  31
  32 require 'god/metric'
  33 require 'god/watch'
  34
  35 require 'god/event_handler'
  36 require 'god/registry'
  37 require 'god/process'
  38
  39 require 'god/sugar'
  40
  41 $:.unshift File.join(File.dirname(__FILE__), *%w[.. ext god])
  42
  43 begin
  44   Syslog.open('god')
  45 rescue RuntimeError
  46   Syslog.reopen('god')
  47 end
  48
  49 God::EventHandler.load
  50
  51 module God
  52   VERSION = '0.3.0'
  53
  54   class << self
  55     attr_accessor :inited, :running, :pending_watches, :host, :port
  56
  57     # drb
  58     attr_accessor :server
  59
  60     # api
  61     attr_accessor :watches, :groups
  62   end
  63
  64   def self.init
  65     # only do this once
  66     return if self.inited
  67
  68     # variable init
  69     self.watches = {}
  70     self.groups = {}
  71     self.pending_watches = []
  72
  73     # yield to the config file
  74     yield self if block_given?
  75
  76     # instantiate server
  77     self.server = Server.new(self.host, self.port)
  78
  79     # init has been executed
  80     self.inited = true
  81
  82     # not yet running
  83     self.running = false
  84   end
  85
  86   # Where pid files created by god will go by default
  87   def self.pid_file_directory
  88     @pid_file_directory ||= '/var/run/god'
  89   end
  90
  91   def self.pid_file_directory=(value)
  92     @pid_file_directory = value
  93   end
  94
  95   # Instantiate a new, empty Watch object and pass it to the mandatory
  96   # block. The attributes of the watch will be set by the configuration
  97   # file.
  98   def self.watch
  99     self.init
 100
 101     w = Watch.new
 102     yield(w)
 103
 104     # if running, completely remove the watch (if necessary) to
 105     # prepare for the reload
 106     existing_watch = self.watches[w.name]
 107     if self.running && existing_watch
 108       self.unwatch(existing_watch)
 109     end
 110
 111     # ensure the new watch has a unique name
 112     if self.watches[w.name] || self.groups[w.name]
 113       abort "Watch name '#{w.name}' already used for a Watch or Group"
 114     end
 115
 116     # add to list of watches
 117     self.watches[w.name] = w
 118
 119     # add to pending watches
 120     self.pending_watches << w
 121
 122     # add to group if specified
 123     if w.group
 124       # ensure group name hasn't been used for a watch already
 125       if self.watches[w.group]
 126         abort "Group name '#{w.group}' already used for a Watch"
 127       end
 128
 129       self.groups[w.group] ||= []
 130       self.groups[w.group] << w
 131     end
 132
 133     # register watch
 134     w.register!
 135   end
 136
 137   def self.unwatch(watch)
 138     # unmonitor
 139     watch.unmonitor
 140
 141     # unregister
 142     watch.unregister!
 143
 144     # remove from watches
 145     self.watches.delete(watch.name)
 146
 147     # remove from groups
 148     if watch.group
 149       self.groups[watch.group].delete(watch)
 150     end
 151   end
 152
 153   def self.control(name, command)
 154     # get the list of watches
 155     watches = Array(self.watches[name] || self.groups[name])
 156
 157     # do the command
 158     case command
 159       when "start", "monitor"
 160         watches.each { |w| w.monitor }
 161       when "restart"
 162         watches.each { |w| w.move(:restart) }
 163       when "stop"
 164         watches.each { |w| w.unmonitor.action(:stop) }
 165       when "unmonitor"
 166         watches.each { |w| w.unmonitor }
 167       else
 168         raise InvalidCommandError.new
 169     end
 170
 171     watches
 172   end
 173
 174   def self.running_load(code)
 175     eval(code)
 176     self.pending_watches.each { |w| w.monitor if w.autostart? }
 177     watches = self.pending_watches.dup
 178     self.pending_watches.clear
 179     watches
 180   end
 181
 182   def self.load(glob)
 183     Dir[glob].each do |f|
 184       Kernel.load f
 185     end
 186   end
 187
 188   def self.start
 189     # make sure there's something to do
 190     if self.watches.nil? || self.watches.empty?
 191       abort "You must specify at least one watch!"
 192     end
 193
 194     # start event handler system
 195     EventHandler.start if EventHandler.loaded?
 196
 197     # start the timer system
 198     Timer.get
 199
 200     # start monitoring any watches set to autostart
 201     self.watches.values.each { |w| w.monitor if w.autostart? }
 202
 203     # clear pending watches
 204     self.pending_watches.clear
 205
 206     # mark as running
 207     self.running = true
 208
 209     # join the timer thread so we don't exit
 210     Timer.get.join
 211   end
 212
 213   def self.at_exit
 214     self.start
 215   end
 216 end
 217
 218 at_exit do
 219   God.at_exit
 220 end