Better handle missing inspection_network

Currently, if the inspection network is not provided, neutron-based
network interfaces fail with something like:

    Driver redfish does not support inspection (disabled or not implemented)

This is utterly misleading. Use a hand-crafted error message instead.
Same for the PXE boot interface. Also add missing documentation.

Change-Id: I79086db1c270e02a6c74b870acc336e8da54dea3

doc/source/admin/inspection/managed.rst

@@ -14,6 +14,15 @@ is the only way to conduct inspection using :ref:`redfish-virtual-media` or
 with :doc:`/admin/dhcp-less`. This mode is engaged automatically when the node
 has sufficient information to configure boot (e.g. ports in case of iPXE).
 
+For network interfaces based on OpenStack Networking (e.g. ``flat`` and
+``neutron``), the UUID or name of the inspection network must be provided via
+configuration or ``driver_info``, for example:
+
+.. code-block:: ini
+
+   [neutron]
+   inspection_network = <NETWORK UUID>
+
 There are a few configuration options that tune managed inspection, the most
 important is ``extra_kernel_params``, which allows adding kernel parameters for
 inspection specifically. This is where you can configure

doc/source/install/enrollment.rst

@@ -230,6 +230,9 @@ and may be combined if desired.
         --driver-info cleaning_network=$CLEAN_UUID_OR_NAME \
         --driver-info provisioning_network=$PROVISION_UUID_OR_NAME
 
+   If you use :doc:`managed inspection </admin/inspection/managed>`, you may
+   also configure ``inspection_network`` the same way.
+
    See :doc:`configure-tenant-networks` for details.
 
 #. You must also inform the Bare Metal service of the network interface cards

ironic/common/neutron.py

@@ -1020,10 +1020,11 @@ class NeutronNetworkInterfaceMixin(object):
         """
         try:
             self.get_inspection_network_uuid(task)
-        except exception.MissingParameterValue:
+        except exception.MissingParameterValue as exc:
             # Fall back to non-managed in-band inspection
             raise exception.UnsupportedDriverExtension(
-                driver=task.node.driver, extension='inspection')
+                _("Insufficient information provided for managed "
+                  "inspection: %s") % exc)
 
     def get_servicing_network_uuid(self, task):
         servicing_network = (

ironic/drivers/modules/pxe_base.py

@@ -441,10 +441,11 @@ class PXEBaseMixin(object):
         """
         try:
             self._validate_common(task)
-        except exception.MissingParameterValue:
+        except exception.MissingParameterValue as exc:
             # Fall back to non-managed in-band inspection
             raise exception.UnsupportedDriverExtension(
-                driver=task.node.driver, extension='inspection')
+                _("Insufficient information provided for managed "
+                  "inspection: %s") % exc)
 
     _RETRY_ALLOWED_STATES = {states.DEPLOYWAIT, states.CLEANWAIT,
                              states.RESCUEWAIT}