Datasources: Formalize DataSource get_data and related properties.

Each DataSource subclass must define its own get_data method. This branch
formalizes our DataSource class to require that subclasses define an
explicit dsname for sourcing cloud-config datasource configuration.
Subclasses must also override the _get_data method or a
NotImplementedError is raised.

The branch also writes /run/cloud-init/instance-data.json. This file
contains all meta-data, user-data and vendor-data and a standardized set
of metadata keys in a json blob which other utilities with root-access
could make use of. Because some meta-data or user-data is potentially
sensitive the file is only readable by root.

Generally most metadata content types should be json serializable. If
specific keys or values are not serializable, those specific values will
be base64encoded and the key path will be listed under the top-level key
'base64-encoded-keys' in instance-data.json. If json writing fails due to
other TypeErrors or UnicodeDecodeErrors, a warning log will be emitted to
/var/log/cloud-init.log and no instance-data.json will be created.

1 files changed, 13 insertions, 6 deletions

diff --git a/tests/unittests/test_datasource/test_cloudstack.py b/tests/unittests/test_datasource/test_cloudstack.py
index 96144b64..d6d2d6b2 100644
--- a/tests/unittests/test_datasource/test_cloudstack.py
+++ b/tests/unittests/test_datasource/test_cloudstack.py
@@ -33,6 +33,7 @@ class TestCloudStackPasswordFetching(CiTestCase):
         self.patches.enter_context(mock.patch(
             mod_name + '.dhcp.networkd_get_option_from_leases',
             get_networkd_server_address))
+        self.tmp = self.tmp_dir()
 
     def _set_password_server_response(self, response_string):
         subp = mock.MagicMock(return_value=(response_string, ''))
@@ -43,26 +44,30 @@ class TestCloudStackPasswordFetching(CiTestCase):
 
     def test_empty_password_doesnt_create_config(self):
         self._set_password_server_response('')
-        ds = DataSourceCloudStack({}, None, helpers.Paths({}))
+        ds = DataSourceCloudStack(
+            {}, None, helpers.Paths({'run_dir': self.tmp}))
         ds.get_data()
         self.assertEqual({}, ds.get_config_obj())
 
     def test_saved_password_doesnt_create_config(self):
         self._set_password_server_response('saved_password')
-        ds = DataSourceCloudStack({}, None, helpers.Paths({}))
+        ds = DataSourceCloudStack(
+            {}, None, helpers.Paths({'run_dir': self.tmp}))
         ds.get_data()
         self.assertEqual({}, ds.get_config_obj())
 
     def test_password_sets_password(self):
         password = 'SekritSquirrel'
         self._set_password_server_response(password)
-        ds = DataSourceCloudStack({}, None, helpers.Paths({}))
+        ds = DataSourceCloudStack(
+            {}, None, helpers.Paths({'run_dir': self.tmp}))
         ds.get_data()
         self.assertEqual(password, ds.get_config_obj()['password'])
 
     def test_bad_request_doesnt_stop_ds_from_working(self):
         self._set_password_server_response('bad_request')
-        ds = DataSourceCloudStack({}, None, helpers.Paths({}))
+        ds = DataSourceCloudStack(
+            {}, None, helpers.Paths({'run_dir': self.tmp}))
         self.assertTrue(ds.get_data())
 
     def assertRequestTypesSent(self, subp, expected_request_types):
@@ -77,14 +82,16 @@ class TestCloudStackPasswordFetching(CiTestCase):
     def test_valid_response_means_password_marked_as_saved(self):
         password = 'SekritSquirrel'
         subp = self._set_password_server_response(password)
-        ds = DataSourceCloudStack({}, None, helpers.Paths({}))
+        ds = DataSourceCloudStack(
+            {}, None, helpers.Paths({'run_dir': self.tmp}))
         ds.get_data()
         self.assertRequestTypesSent(subp,
                                     ['send_my_password', 'saved_password'])
 
     def _check_password_not_saved_for(self, response_string):
         subp = self._set_password_server_response(response_string)
-        ds = DataSourceCloudStack({}, None, helpers.Paths({}))
+        ds = DataSourceCloudStack(
+            {}, None, helpers.Paths({'run_dir': self.tmp}))
         ds.get_data()
         self.assertRequestTypesSent(subp, ['send_my_password'])