create a shutdown_command method in distro classes (#567)

Under FreeBSD, we want to use "shutdown -p" for poweroff.

Alpine Linux also has some specificities.

We choose to define a method that returns the shutdown command line to
use, rather than a method that actually does the shutdown. This makes it
easier to have the tests in test_handler_power_state do their
verifications.

Two tests are added for the special behaviours that are known so far.

1 files changed, 26 insertions, 0 deletions

diff --git a/cloudinit/distros/alpine.py b/cloudinit/distros/alpine.py
index e42443fc..e92ff3fb 100644
--- a/cloudinit/distros/alpine.py
+++ b/cloudinit/distros/alpine.py
@@ -162,4 +162,30 @@ class Distro(distros.Distro):
 
         return self._preferred_ntp_clients
 
+    def shutdown_command(self, mode='poweroff', delay='now', message=None):
+        # called from cc_power_state_change.load_power_state
+        # Alpine has halt/poweroff/reboot, with the following specifics:
+        # - we use them rather than the generic "shutdown"
+        # - delay is given with "-d [integer]"
+        # - the integer is in seconds, cannot be "now", and takes no "+"
+        # - no message is supported (argument ignored, here)
+
+        command = [mode, "-d"]
+
+        # Convert delay from minutes to seconds, as Alpine's
+        # halt/poweroff/reboot commands take seconds rather than minutes.
+        if delay == "now":
+            # Alpine's commands do not understand "now".
+            command += ['0']
+        else:
+            try:
+                command.append(str(int(delay) * 60))
+            except ValueError as e:
+                raise TypeError(
+                    "power_state[delay] must be 'now' or '+m' (minutes)."
+                    " found '%s'." % (delay,)
+                ) from e
+
+        return command
+
 # vi: ts=4 expandtab