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, 5 insertions, 10 deletions

diff --git a/cloudinit/handlers/cloud_config.py b/cloudinit/handlers/cloud_config.py
index 178a5b9b..99bf0e61 100644
--- a/cloudinit/handlers/cloud_config.py
+++ b/cloudinit/handlers/cloud_config.py
@@ -42,14 +42,12 @@ DEF_MERGERS = mergers.string_extract_mergers('dict(replace)+list()+str()')
 CLOUD_PREFIX = "#cloud-config"
 JSONP_PREFIX = "#cloud-config-jsonp"
 
-# The file header -> content types this module will handle.
-CC_TYPES = {
-    JSONP_PREFIX: handlers.type_from_starts_with(JSONP_PREFIX),
-    CLOUD_PREFIX: handlers.type_from_starts_with(CLOUD_PREFIX),
-}
-
 
 class CloudConfigPartHandler(handlers.Handler):
+
+    # The content prefixes this handler understands.
+    prefixes = [CLOUD_PREFIX, JSONP_PREFIX]
+
     def __init__(self, paths, **_kwargs):
         handlers.Handler.__init__(self, PER_ALWAYS, version=3)
         self.cloud_buf = None
@@ -58,9 +56,6 @@ class CloudConfigPartHandler(handlers.Handler):
             self.cloud_fn = paths.get_ipath(_kwargs["cloud_config_path"])
         self.file_names = []
 
-    def list_types(self):
-        return list(CC_TYPES.values())
-
     def _write_cloud_config(self):
         if not self.cloud_fn:
             return
@@ -138,7 +133,7 @@ class CloudConfigPartHandler(handlers.Handler):
             # First time through, merge with an empty dict...
             if self.cloud_buf is None or not self.file_names:
                 self.cloud_buf = {}
-            if ctype == CC_TYPES[JSONP_PREFIX]:
+            if ctype == handlers.INCLUSION_TYPES_MAP[JSONP_PREFIX]:
                 self._merge_patch(payload)
             else:
                 self._merge_part(payload, headers)