power_state: support 'condition' argument

  
  if 'condition' is provided to config in power_state, then
  consult it before powering off.
  
  This allows the user to shut down only if a condition is met, and
  leave the system in a debuggable state otherwise.
  
  An example is as simple as:
   power_state:
     mode: poweroff
     condition: ['sh', '-c', '[ -f /disable-poweroff ]']

1 files changed, 9 insertions, 0 deletions

diff --git a/doc/examples/cloud-config-power-state.txt b/doc/examples/cloud-config-power-state.txt
index 8df14366..b470153d 100644
--- a/doc/examples/cloud-config-power-state.txt
+++ b/doc/examples/cloud-config-power-state.txt
@@ -23,9 +23,18 @@
 # 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.
+# condition: apply state change only if condition is met.
+#            May be boolean True (always met), or False (never met),
+#            or a command string or list to be executed.
+#            command's exit code indicates:
+#               0: condition met
+#               1: condition not met
+#            other exit codes will result in 'not met', but are reserved
+#            for future use.
 #
 power_state:
  delay: "+30"
  mode: poweroff
  message: Bye Bye
  timeout: 30
+ condition: True