Change exception when store plugin is misconfigured

If we try to get a plugin that supports the "retrieve" and "delete"
operations and the plugin is not there, is is probably due to a server
misconfiguration, since the plugin name is gotten from the metadata
from the database; And if it was there in the first place, it means
that it once was actually able to store that secret using a valid
plugin. Thus, a new exception is raised if this is the case.

Change-Id: I2be8b9dd17a7bd12f10e55945b09257fce616f3d
Closes-Bug: #1416075

barbican/plugin/interface/secret_store.py

@@ -152,6 +152,12 @@ class SecretStorePluginsNotConfigured(exception.BarbicanException):
         )
 
 
+class StorePluginNotAvailableOrMisconfigured(exception.BarbicanException):
+    message = u._("The requested Store Plugin %(plugin_name) is not "
+                  "currently available. This is probably a server "
+                  "misconfiguration.")
+
+
 class SecretType(object):
 
     """Constant to define the symmetric key type.
@@ -470,13 +476,22 @@ class SecretStorePluginManager(named.NamedExtensionManager):
     def get_plugin_retrieve_delete(self, plugin_name):
         """Gets a secret retrieve/delete plugin.
 
+        If this function is being called, it is because we are trying to
+        retrieve or delete an already stored secret. Thus, the plugin name is
+        actually gotten from the plugin metadata that has already been stored
+        in the database. So, in this case, if this plugin is not available,
+        this might be due to a server misconfiguration.
+
         :returns: SecretStoreBase plugin implementation
+        :raises: StorePluginNotAvailableOrMisconfigured: If the plugin wasn't
+                 found it's because the plugin parameters were not properly
+                 configured on the database side.
         """
 
         for ext in self.extensions:
             if utils.generate_fullname_for(ext.obj) == plugin_name:
                 return ext.obj
-        raise SecretStorePluginNotFound(plugin_name)
+        raise StorePluginNotAvailableOrMisconfigured(plugin_name)
 
     @_enforce_extensions_configured
     def get_plugin_generate(self, key_spec):

barbican/tests/plugin/interface/test_secret_store.py

@@ -205,6 +205,22 @@ class WhenTestingSecretStorePluginManager(utils.BaseTestCase):
             transport_key_needed=True,
         )
 
+    @mock.patch('barbican.common.utils.generate_fullname_for')
+    def test_get_retrieve_plugin_raises_when_not_available(
+            self, generate_full_name_for):
+        plugin = TestSecretStore([str.KeyAlgorithm.AES])
+        plugin_mock = mock.MagicMock(obj=plugin)
+        self.manager.extensions = [plugin_mock]
+
+        generate_full_name_for.return_value = "another plugin name"
+        plugin_name = 'plugin name searched for'
+
+        self.assertRaises(
+            str.StorePluginNotAvailableOrMisconfigured,
+            self.manager.get_plugin_retrieve_delete,
+            plugin_name=plugin_name,
+        )
+
     def test_get_store_plugin_with_tkey_and_supports_storage(self):
         plugin1 = TestSecretStore([str.KeyAlgorithm.AES])
         plugin1_mock = mock.MagicMock(obj=plugin1)