Change validate() to raise instead of returning T/F

Robert was right - it's better to allow driver.interface.validate to
raise an exception, and let that bubble up and be wrapped by the API, or
logged, than to wrap it at a low level and convert to True/False.

This patch changes the existing drivers' validate methods to remove
the exception wrapping, and updates some doc strings.

Change-Id: I02372db64ea0eb85a3c0a00de292c87d286808e1

ironic/drivers/base.py

@@ -84,7 +84,7 @@ class DeployInterface(object):
         deploy images to the node.
 
         :param node: a single Node to validate.
-        :returns: True or False, depending on capabilities.
+        :raises: InvalidParameterValue
         """
 
     @abc.abstractmethod
@@ -124,7 +124,7 @@ class PowerInterface(object):
         manage the power state of the node.
 
         :param node: a single Node to validate.
-        :returns: True or False, depending on capabilities.
+        :raises: InvalidParameterValue
         """
 
     @abc.abstractmethod
@@ -163,7 +163,7 @@ class ConsoleInterface(object):
         provide console access to the Node.
 
         :param node: a single Node to validate.
-        :returns: True or False, depending on capabilities.
+        :raises: InvalidParameterValue
         """
 
     @abc.abstractmethod
@@ -188,7 +188,11 @@ class RescueInterface(object):
 
     @abc.abstractmethod
     def validate(self, node):
-        """Validate the rescue info stored in the node' properties."""
+        """Validate the rescue info stored in the node' properties.
+
+        :param node: a single Node to validate.
+        :raises: InvalidParameterValue
+        """
 
     @abc.abstractmethod
     def rescue(self, task, node):
@@ -216,7 +220,11 @@ class VendorInterface(object):
 
     @abc.abstractmethod
     def validate(self, node):
-        """Validate vendor-specific info stored in the node' properties."""
+        """Validate vendor-specific info stored in the node' properties.
+
+        :param node: a single Node to validate.
+        :raises: InvalidParameterValue
+        """
 
     @abc.abstractmethod
     def vendor_passthru(self, task, node, *args, **kwargs):

ironic/drivers/modules/ipmi.py

@@ -191,12 +191,12 @@ def _power_status(driver_info):
 class IPMIPower(base.PowerInterface):
 
     def validate(self, node):
-        """Check that node['driver_info'] contains IPMI credentials."""
-        try:
-            _parse_driver_info(node)
-        except exception.InvalidParameterValue:
-            return False
-        return True
+        """Check that node['driver_info'] contains IPMI credentials.
+
+        :param node: Single node object.
+        :raises: InvalidParameterValue
+        """
+        _parse_driver_info(node)
 
     def get_power_state(self, task, node):
         """Get the current power state."""

ironic/drivers/modules/ssh.py

@@ -267,14 +267,9 @@ class SSHPower(base.PowerInterface):
         """Check that node['driver_info'] contains the requisite fields.
 
         :param node: Single node object.
-
-        :returns: True / False.
+        :raises: InvalidParameterValue
         """
-        try:
-            _parse_driver_info(node)
-        except exception.InvalidParameterValue:
-            return False
-        return True
+        _parse_driver_info(node)
 
     def get_power_state(self, task, node):
         """Get the current power state.