Merge "Added empty metadata service: EmptyMetadataService"

cloudbaseinit/metadata/services/base.py

@@ -297,3 +297,32 @@ class BaseHTTPMetadataService(BaseMetadataService):
             raise
 
         return response
+
+
+class EmptyMetadataService(BaseMetadataService):
+
+    """Empty metadata service implementation.
+
+    The empty metadata service can be used to run plugins that do not
+    rely on metadata service information, like setting ntp, mtu, etc.
+    It can be used also as a fallback metadata service, in case no other
+    previous metadata service could be loaded.
+    """
+
+    def __init__(self):
+        super(EmptyMetadataService, self).__init__()
+
+    def _get_data(self, path):
+        pass
+
+    def load(self):
+        return True
+
+    def get_admin_username(self):
+        raise NotExistingMetadataException()
+
+    def get_admin_password(self):
+        raise NotExistingMetadataException()
+
+    def is_password_changed(self):
+        raise NotExistingMetadataException()

cloudbaseinit/tests/metadata/services/test_base.py

@@ -183,3 +183,27 @@ class TestBaseHTTPMetadataService(unittest.TestCase):
         ssl_error = requests.exceptions.SSLError()
         self._test_get_data(expected_response=ssl_error,
                             expected_value=exception.CertificateVerifyFailed)
+
+
+class TestEmptyMetadataService(unittest.TestCase):
+
+    def setUp(self):
+        self._service = base.EmptyMetadataService()
+
+    def test_get_name(self):
+        self.assertEqual(self._service.get_name(), 'EmptyMetadataService')
+
+    def test__get_data(self):
+        self.assertFalse(self._service._get_data('fake_path'))
+
+    def test_get_admin_username(self):
+        self.assertRaises(base.NotExistingMetadataException,
+                          self._service.get_admin_username)
+
+    def test_get_admin_password(self):
+        self.assertRaises(base.NotExistingMetadataException,
+                          self._service.get_admin_password)
+
+    def test_is_password_changed(self):
+        self.assertRaises(base.NotExistingMetadataException,
+                          self._service.is_password_changed)

doc/source/services.rst

@@ -338,3 +338,27 @@ Config options for `default` section:
 
     * retry_count (integer: 5)
     * retry_count_interval (integer: 4)
+
+EMPTY
+-----
+
+.. class:: cloudbaseinit.metadata.services.base.EmptyMetadataService
+
+The empty metadata service can be used to run plugins that do not
+rely on metadata service information, like setting NTP, MTU,
+extending volumes, local scripts execution, licensing, etc.
+
+It can be used also as a fallback metadata service, in case no other
+previous metadata service could be loaded.
+
+EmptyMetadataService does not support the following plugins:
+  * cloudbaseinit.plugins.windows.createuser.CreateUserPlugin
+  * cloudbaseinit.plugins.common.setuserpassword.SetUserPasswordPlugin
+  * cloudbaseinit.plugins.common.sshpublickeys.SetUserSSHPublicKeysPlugin
+  * cloudbaseinit.plugins.windows.winrmcertificateauth.ConfigWinRMCertificateAuthPlugin
+
+If any of the plugins defined above are executed,
+they will fail with exception NotExistingMetadataException. The reason
+for the hardcoded failure is that these plugins rely on metadata to execute
+correctly. If metadata like username or password is not provided,
+these plugins can lock or misconfigure the user, leading to unwanted problems.