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, 9 insertions, 4 deletions

diff --git a/tests/unittests/test_datasource/test_scaleway.py b/tests/unittests/test_datasource/test_scaleway.py
index 436df9ee..8dec06b1 100644
--- a/tests/unittests/test_datasource/test_scaleway.py
+++ b/tests/unittests/test_datasource/test_scaleway.py
@@ -9,7 +9,7 @@ from cloudinit import helpers
 from cloudinit import settings
 from cloudinit.sources import DataSourceScaleway
 
-from cloudinit.tests.helpers import mock, HttprettyTestCase, TestCase
+from cloudinit.tests.helpers import mock, HttprettyTestCase, CiTestCase
 
 
 class DataResponses(object):
@@ -63,7 +63,11 @@ class MetadataResponses(object):
         return 200, headers, json.dumps(cls.FAKE_METADATA)
 
 
-class TestOnScaleway(TestCase):
+class TestOnScaleway(CiTestCase):
+
+    def setUp(self):
+        super(TestOnScaleway, self).setUp()
+        self.tmp = self.tmp_dir()
 
     def install_mocks(self, fake_dmi, fake_file_exists, fake_cmdline):
         mock, faked = fake_dmi
@@ -91,7 +95,7 @@ class TestOnScaleway(TestCase):
 
         # When not on Scaleway, get_data() returns False.
         datasource = DataSourceScaleway.DataSourceScaleway(
-            settings.CFG_BUILTIN, None, helpers.Paths({})
+            settings.CFG_BUILTIN, None, helpers.Paths({'run_dir': self.tmp})
         )
         self.assertFalse(datasource.get_data())
 
@@ -159,8 +163,9 @@ def get_source_address_adapter(*args, **kwargs):
 class TestDataSourceScaleway(HttprettyTestCase):
 
     def setUp(self):
+        tmp = self.tmp_dir()
         self.datasource = DataSourceScaleway.DataSourceScaleway(
-            settings.CFG_BUILTIN, None, helpers.Paths({})
+            settings.CFG_BUILTIN, None, helpers.Paths({'run_dir': tmp})
         )
         super(TestDataSourceScaleway, self).setUp()