Add reboot_delay option to snmp driver

When node is powered off via "soft off" (during deploy with agent for
example) a off/on cycle is required on external power controller.
If pause between off and on is too short node's hardware unable
to detect external power loss.
This patch adds new 'reboot_delay' config option. Some of
SNMP-enabled power controller have own value for this pause
(configurable or hardcoded). So default value of Ironic option
is "0" for keeping of current behavior.

Closes-Bug: #1506860
Change-Id: I91617f1a296ad38ff4c31872e6e3ac20f8619a38

etc/ironic/ironic.conf.sample

@@ -1810,6 +1810,10 @@
 # value)
 #power_timeout=10
 
+# Time (in seconds) to sleep between when rebooting (powering
+# off and on again) (integer value)
+#reboot_delay=0
+
 
 [ssh]
 

ironic/drivers/modules/snmp.py

@@ -28,6 +28,7 @@ models.
 """
 
 import abc
+import time
 
 from oslo_config import cfg
 from oslo_log import log as logging
@@ -55,7 +56,14 @@ else:
 opts = [
     cfg.IntOpt('power_timeout',
                default=10,
-               help=_('Seconds to wait for power action to be completed'))
+               help=_('Seconds to wait for power action to be completed')),
+    # NOTE(yuriyz): some of SNMP-enabled hardware have own options for pause
+    # between off and on. This option guarantees minimal value.
+    cfg.IntOpt('reboot_delay',
+               default=0,
+               min=0,
+               help=_('Time (in seconds) to sleep between when rebooting '
+                      '(powering off and on again)'))
 ]
 
 LOG = logging.getLogger(__name__)
@@ -310,6 +318,7 @@ class SNMPDriverBase(object):
         power_result = self.power_off()
         if power_result != states.POWER_OFF:
             return states.ERROR
+        time.sleep(CONF.snmp.reboot_delay)
         power_result = self.power_on()
         if power_result != states.POWER_ON:
             return states.ERROR

ironic/tests/unit/drivers/modules/test_snmp.py

@@ -20,6 +20,8 @@
 
 """Test class for SNMP power driver module."""
 
+import time
+
 import mock
 from oslo_config import cfg
 from pysnmp.entity.rfc3413.oneliner import cmdgen
@@ -754,6 +756,23 @@ class SNMPDeviceDriverTestCase(db_base.DbTestCase):
         mock_client.set.assert_has_calls(calls)
         mock_client.get.assert_called_once_with(driver._snmp_oid())
 
+    @mock.patch.object(time, 'sleep', autospec=True)
+    def test_power_reset_delay_option(self, mock_sleep, mock_get_client):
+        # Test for 'reboot_delay' config option
+        self.config(reboot_delay=5, group='snmp')
+        mock_client = mock_get_client.return_value
+        driver = snmp._get_driver(self.node)
+        mock_client.get.side_effect = [driver.value_power_off,
+                                       driver.value_power_on]
+        pstate = driver.power_reset()
+        calls = [mock.call(driver._snmp_oid(), driver.value_power_off),
+                 mock.call(driver._snmp_oid(), driver.value_power_on)]
+        mock_client.set.assert_has_calls(calls)
+        calls = [mock.call(driver._snmp_oid())] * 2
+        mock_client.get.assert_has_calls(calls)
+        self.assertEqual(states.POWER_ON, pstate)
+        mock_sleep.assert_called_once_with(5)
+
     def test_power_reset_on_snmp_get_failure(self, mock_get_client):
         # Ensure SNMP failure exceptions raised during a reset power on get
         # operation are propagated