forked from mojombo/god
/
task.rb
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/
task.rb
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module God
class Task
attr_accessor :name, :interval, :group, :valid_states, :initial_state, :driver
attr_writer :autostart
def autostart?; @autostart; end
# api
attr_accessor :state, :behaviors, :metrics, :directory
def initialize
@autostart ||= true
# initial state is unmonitored
self.state = :unmonitored
# the list of behaviors
self.behaviors = []
# the list of conditions for each action
self.metrics = {nil => [], :unmonitored => [], :stop => []}
# the condition -> metric lookup
self.directory = {}
# driver
self.driver = Driver.new(self)
end
def prepare
self.valid_states.each do |state|
self.metrics[state] ||= []
end
end
def valid?
valid = true
# a name must be specified
if self.name.nil?
valid = false
applog(self, :error, "No name was specified")
end
# valid_states must be specified
if self.valid_states.nil?
valid = false
applog(self, :error, "No valid_states array was specified")
end
# valid_states must be specified
if self.initial_state.nil?
valid = false
applog(self, :error, "No initial_state was specified")
end
valid
end
###########################################################################
#
# Advanced mode
#
###########################################################################
def canonical_hash_form(to)
to.instance_of?(Symbol) ? {true => to} : to
end
# Define a transition handler which consists of a set of conditions
def transition(start_states, end_states)
# convert end_states into canonical hash form
canonical_end_states = canonical_hash_form(end_states)
Array(start_states).each do |start_state|
# validate start state
unless self.valid_states.include?(start_state)
abort "Invalid state :#{start_state}. Must be one of the symbols #{self.valid_states.map{|x| ":#{x}"}.join(', ')}"
end
# create a new metric to hold the watch, end states, and conditions
m = Metric.new(self, canonical_end_states)
if block_given?
# let the config file define some conditions on the metric
yield(m)
else
# add an :always condition if no block
m.condition(:always) do |c|
c.what = true
end
end
# populate the condition -> metric directory
m.conditions.each do |c|
self.directory[c] = m
end
# record the metric
self.metrics[start_state] ||= []
self.metrics[start_state] << m
end
end
def lifecycle
# create a new metric to hold the watch and conditions
m = Metric.new(self)
# let the config file define some conditions on the metric
yield(m)
# populate the condition -> metric directory
m.conditions.each do |c|
self.directory[c] = m
end
# record the metric
self.metrics[nil] << m
end
###########################################################################
#
# Lifecycle
#
###########################################################################
# Enable monitoring
#
# Returns nothing
def monitor
self.move(self.initial_state)
end
# Disable monitoring
#
# Returns nothing
def unmonitor
self.move(:unmonitored)
end
# Move to the givent state
# +to_state+ is the Symbol representing the state to move to
#
# Returns Task (self)
def move(to_state)
if Thread.current != self.driver.thread
# called from outside Driver
# send an async message to Driver
self.driver.message(:move, [to_state])
else
# called from within Driver
# record original info
orig_to_state = to_state
from_state = self.state
# log
msg = "#{self.name} move '#{from_state}' to '#{to_state}'"
applog(self, :info, msg)
# cleanup from current state
self.driver.clear_events
self.metrics[from_state].each { |m| m.disable }
if to_state == :unmonitored
self.metrics[nil].each { |m| m.disable }
end
# perform action
self.action(to_state)
# enable simple mode
if [:start, :restart].include?(to_state) && self.metrics[to_state].empty?
to_state = :up
end
# move to new state
self.metrics[to_state].each { |m| m.enable }
# if no from state, enable lifecycle metric
if from_state == :unmonitored
self.metrics[nil].each { |m| m.enable }
end
# set state
self.state = to_state
# broadcast to interested TriggerConditions
Trigger.broadcast(self, :state_change, [from_state, orig_to_state])
# log
msg = "#{self.name} moved '#{from_state}' to '#{to_state}'"
applog(self, :info, msg)
end
self
end
# Notify the Driver that an EventCondition has triggered
#
# Returns nothing
def trigger(condition)
self.driver.message(:handle_event, [condition])
end
def signal(sig)
# noop
end
###########################################################################
#
# Actions
#
###########################################################################
def method_missing(sym, *args)
unless (sym.to_s =~ /=$/)
super
end
base = sym.to_s.chop.intern
unless self.valid_states.include?(base)
super
end
self.class.send(:attr_accessor, base)
self.send(sym, *args)
end
# Perform the given action
# +a+ is the action Symbol
# +c+ is the Condition
#
# Returns Task (self)
def action(a, c = nil)
if Thread.current != self.driver.thread
# called from outside Driver
# send an async message to Driver
self.driver.message(:action, [a, c])
else
# called from within Driver
if self.respond_to?(a)
command = self.send(a)
case command
when String
msg = "#{self.name} #{a}: #{command}"
applog(self, :info, msg)
system(command)
when Proc
msg = "#{self.name} #{a}: lambda"
applog(self, :info, msg)
command.call
else
raise NotImplementedError
end
end
end
end
###########################################################################
#
# Events
#
###########################################################################
def attach(condition)
case condition
when PollCondition
self.driver.schedule(condition, 0)
when EventCondition, TriggerCondition
condition.register
end
end
def detach(condition)
case condition
when PollCondition
condition.reset
when EventCondition, TriggerCondition
condition.deregister
end
end
###########################################################################
#
# Registration
#
###########################################################################
def register!
# override if necessary
end
def unregister!
driver.shutdown
end
###########################################################################
#
# Handlers
#
###########################################################################
# Evaluate and handle the given poll condition. Handles logging
# notifications, and moving to the new state if necessary
# +condition+ is the Condition to handle
#
# Returns nothing
def handle_poll(condition)
# lookup metric
metric = self.directory[condition]
# run the test
begin
result = condition.test
rescue Object => e
cname = condition.class.to_s.split('::').last
message = format("Unhandled exception in %s condition - (%s): %s\n%s",
cname, e.class, e.message, e.backtrace.join("\n"))
applog(self, :error, message)
result = false
end
# log
messages = self.log_line(self, metric, condition, result)
# notify
if result && condition.notify
self.notify(condition, messages.last)
end
# after-condition
condition.after
# get the destination
dest =
if result && condition.transition
# condition override
condition.transition
else
# regular
metric.destination && metric.destination[result]
end
# transition or reschedule
if dest
# transition
begin
self.move(dest)
rescue EventRegistrationFailedError
msg = self.name + ' Event registration failed, moving back to previous state'
applog(self, :info, msg)
dest = self.state
retry
end
else
# reschedule
self.driver.schedule(condition)
end
end
# Asynchronously evaluate and handle the given event condition. Handles logging
# notifications, and moving to the new state if necessary
# +condition+ is the Condition to handle
#
# Returns nothing
def handle_event(condition)
# lookup metric
metric = self.directory[condition]
# log
messages = self.log_line(self, metric, condition, true)
# notify
if condition.notify
self.notify(condition, messages.last)
end
# get the destination
dest =
if condition.transition
# condition override
condition.transition
else
# regular
metric.destination && metric.destination[true]
end
if dest
self.move(dest)
end
end
# Determine whether a trigger happened
# +metric+ is the Metric
# +result+ is the result from the condition's test
#
# Returns Boolean
def trigger?(metric, result)
metric.destination && metric.destination[result]
end
# Log info about the condition and return the list of messages logged
# +watch+ is the Watch
# +metric+ is the Metric
# +condition+ is the Condition
# +result+ is the Boolean result of the condition test evaluation
#
# Returns String[]
def log_line(watch, metric, condition, result)
status =
if self.trigger?(metric, result)
"[trigger]"
else
"[ok]"
end
messages = []
# log info if available
if condition.info
Array(condition.info).each do |condition_info|
messages << "#{watch.name} #{status} #{condition_info} (#{condition.base_name})"
applog(watch, :info, messages.last)
end
else
messages << "#{watch.name} #{status} (#{condition.base_name})"
applog(watch, :info, messages.last)
end
# log
debug_message = watch.name + ' ' + condition.base_name + " [#{result}] " + self.dest_desc(metric, condition)
applog(watch, :debug, debug_message)
messages
end
# Format the destination specification for use in debug logging
# +metric+ is the Metric
# +condition+ is the Condition
#
# Returns String
def dest_desc(metric, condition)
if condition.transition
{true => condition.transition}.inspect
else
if metric.destination
metric.destination.inspect
else
'none'
end
end
end
# Notify all recipeients of the given condition with the specified message
# +condition+ is the Condition
# +message+ is the String message to send
#
# Returns nothing
def notify(condition, message)
spec = Contact.normalize(condition.notify)
unmatched = []
# resolve contacts
resolved_contacts =
spec[:contacts].inject([]) do |acc, contact_name_or_group|
cons = Array(God.contacts[contact_name_or_group] || God.contact_groups[contact_name_or_group])
unmatched << contact_name_or_group if cons.empty?
acc += cons
acc
end
# warn about unmatched contacts
unless unmatched.empty?
msg = "#{condition.watch.name} no matching contacts for '#{unmatched.join(", ")}'"
applog(condition.watch, :warn, msg)
end
# notify each contact
resolved_contacts.each do |c|
host = `hostname`.chomp rescue 'none'
begin
c.notify(message, Time.now, spec[:priority], spec[:category], host)
msg = "#{condition.watch.name} #{c.info ? c.info : "notification sent for contact: #{c.name}"} (#{c.base_name})"
applog(condition.watch, :info, msg % [])
rescue Exception => e
applog(condition.watch, :error, "#{e.message} #{e.backtrace}")
msg = "#{condition.watch.name} Failed to deliver notification for contact: #{c.name} (#{c.base_name})"
applog(condition.watch, :error, msg % [])
end
end
end
end
end