user-data: jinja template to render instance-data.json in cloud-config

Allow users to provide '## template: jinja' as the first line or their
#cloud-config or custom script user-data parts. When this header exists,
the cloud-config or script will be rendered as a jinja template.

All instance metadata keys and values present in
/run/cloud-init/instance-data.json will be available as jinja variables
for the template. This means any cloud-config module or script can
reference any standardized instance data in templates and scripts.

Additionally, any standardized instance-data.json keys scoped below a
'<v#>' key will be promoted as a top-level key for ease of reference in
templates. This means that '{{ local_hostname }}' is the same as using the
latest '{{ v#.local_hostname }}'.

Since instance-data is written to /run/cloud-init/instance-data.json, make
sure it is persisted across reboots when the cached datasource opject is
reloaded.

LP: #1791781

1 files changed, 9 insertions, 0 deletions

diff --git a/cloudinit/tests/helpers.py b/cloudinit/tests/helpers.py
index 42f56c27..2eb7b0cd 100644
--- a/cloudinit/tests/helpers.py
+++ b/cloudinit/tests/helpers.py
@@ -32,6 +32,7 @@ from cloudinit import cloud
 from cloudinit import distros
 from cloudinit import helpers as ch
 from cloudinit.sources import DataSourceNone
+from cloudinit.templater import JINJA_AVAILABLE
 from cloudinit import util
 
 _real_subp = util.subp
@@ -518,6 +519,14 @@ def skipUnlessJsonSchema():
         _missing_jsonschema_dep, "No python-jsonschema dependency present.")
 
 
+def skipUnlessJinja():
+    return skipIf(not JINJA_AVAILABLE, "No jinja dependency present.")
+
+
+def skipIfJinja():
+    return skipIf(JINJA_AVAILABLE, "Jinja dependency present.")
+
+
 # older versions of mock do not have the useful 'assert_not_called'
 if not hasattr(mock.Mock, 'assert_not_called'):
     def __mock_assert_not_called(mmock):