Check hooks availability on start-up

Otherwise we fail in the middle of processing.

Change-Id: I2d44fc03111bdeeea93c8d95f8441ce1b81cf235
Closes-Bug: #1418005

ironic_discoverd/main.py

@@ -23,12 +23,13 @@ import flask
 from oslo_config import cfg
 from oslo_utils import uuidutils
 
-from ironic_discoverd.common.i18n import _, _LE, _LW
+from ironic_discoverd.common.i18n import _, _LC, _LE, _LI, _LW
 # Import configuration options
 from ironic_discoverd import conf  # noqa
 from ironic_discoverd import firewall
 from ironic_discoverd import introspect
 from ironic_discoverd import node_cache
+from ironic_discoverd.plugins import base as plugins_base
 from ironic_discoverd import process
 from ironic_discoverd import utils
 
@@ -163,6 +164,15 @@ def init():
     node_cache.init()
     check_ironic_available()
 
+    try:
+        hooks = [ext.name for ext in plugins_base.processing_hooks_manager()]
+    except KeyError as exc:
+        # stevedore raises KeyError on missing hook
+        LOG.critical(_LC('Hook %s failed to load or was not found'), str(exc))
+        sys.exit(1)
+
+    LOG.info(_LI('Enabled processing hooks: %s'), hooks)
+
     if CONF.discoverd.manage_firewall:
         firewall.init()
         period = CONF.discoverd.firewall_update_period

ironic_discoverd/test/test_main.py

@@ -244,3 +244,13 @@ class TestInit(test_base.BaseTest):
         for (args, call) in zip(spawn_n_expected_args,
                                 spawn_n_call_args_list):
             self.assertEqual(args, call[0])
+
+    @mock.patch.object(main.LOG, 'critical')
+    def test_init_failed_processing_hook(self, mock_log, mock_node_cache,
+                                         mock_get_client, mock_auth,
+                                         mock_firewall, mock_spawn_n):
+        CONF.set_override('processing_hooks', 'foo!', 'discoverd')
+        plugins_base._HOOKS_MGR = None
+
+        self.assertRaises(SystemExit, main.init)
+        mock_log.assert_called_once_with(mock.ANY, "'foo!'")