power_state_change: convert an int input for delay to string, improve doc

this adds 'timeout' to the documentation for power_state_change, and
supports delay being an integer or a string.  This is so that yaml
can contain:
 delay: 30
rather than
 delay: "+30"
or
 dealy: "30"

cloudinit/config/cc_power_state_change.py

@@ -75,6 +75,12 @@ def load_power_state(cfg):
                         ','.join(opt_map.keys()))
 
     delay = pstate.get("delay", "now")
+    # convert integer 30 or string '30' to '+30'
+    try:
+        delay = "+%s" % int(delay)
+    except ValueError:
+        pass
+
     if delay != "now" and not re.match(r"\+[0-9]+", delay):
         raise TypeError("power_state[delay] must be 'now' or '+m' (minutes).")
 

doc/examples/cloud-config-power-state.txt

@@ -12,11 +12,20 @@
 # that may go to the console as a result of system services like
 # syslog being taken down while cloud-init is running.
 #
+# If you delay '+5' (5 minutes) and have a timeout of
+# 120 (2 minutes), then the max time until shutdown will be 7 minutes.
+# cloud-init will invoke 'shutdown +5' after the process finishes, or
+# when 'timeout' seconds have elapsed.
+#
 # delay: form accepted by shutdown.  default is 'now'. other format
 #        accepted is +m (m in minutes)
 # mode: required. must be one of 'poweroff', 'halt', 'reboot'
 # message: provided as the message argument to 'shutdown'. default is none.
+# timeout: the amount of time to give the cloud-init process to finish
+#          before executing shutdown.
+#
 power_state:
- delay: 30
+ delay: "+30"
  mode: poweroff
  message: Bye Bye
+ timeout: 30