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, 7 insertions, 4 deletions

diff --git a/tests/unittests/test_datasource/test_digitalocean.py b/tests/unittests/test_datasource/test_digitalocean.py
index f264f361..ec321733 100644
--- a/tests/unittests/test_datasource/test_digitalocean.py
+++ b/tests/unittests/test_datasource/test_digitalocean.py
@@ -13,7 +13,7 @@ from cloudinit import settings
 from cloudinit.sources import DataSourceDigitalOcean
 from cloudinit.sources.helpers import digitalocean
 
-from cloudinit.tests.helpers import mock, TestCase
+from cloudinit.tests.helpers import mock, CiTestCase
 
 DO_MULTIPLE_KEYS = ["ssh-rsa AAAAB3NzaC1yc2EAAAA... test1@do.co",
                     "ssh-rsa AAAAB3NzaC1yc2EAAAA... test2@do.co"]
@@ -135,14 +135,17 @@ def _mock_dmi():
     return (True, DO_META.get('id'))
 
 
-class TestDataSourceDigitalOcean(TestCase):
+class TestDataSourceDigitalOcean(CiTestCase):
     """
     Test reading the meta-data
     """
+    def setUp(self):
+        super(TestDataSourceDigitalOcean, self).setUp()
+        self.tmp = self.tmp_dir()
 
     def get_ds(self, get_sysinfo=_mock_dmi):
         ds = DataSourceDigitalOcean.DataSourceDigitalOcean(
-            settings.CFG_BUILTIN, None, helpers.Paths({}))
+            settings.CFG_BUILTIN, None, helpers.Paths({'run_dir': self.tmp}))
         ds.use_ip4LL = False
         if get_sysinfo is not None:
             ds._get_sysinfo = get_sysinfo
@@ -194,7 +197,7 @@ class TestDataSourceDigitalOcean(TestCase):
         self.assertIsInstance(ds.get_public_ssh_keys(), list)
 
 
-class TestNetworkConvert(TestCase):
+class TestNetworkConvert(CiTestCase):
 
     @mock.patch('cloudinit.net.get_interfaces_by_mac')
     def _get_networking(self, m_get_by_mac):