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, 4 insertions, 1 deletions

diff --git a/cloudinit/cmd/devel/parser.py b/cloudinit/cmd/devel/parser.py
index 40a4b019..99a234ce 100644
--- a/cloudinit/cmd/devel/parser.py
+++ b/cloudinit/cmd/devel/parser.py
@@ -8,6 +8,7 @@ import argparse
 from cloudinit.config import schema
 
 from . import net_convert
+from . import render
 
 
 def get_parser(parser=None):
@@ -22,7 +23,9 @@ def get_parser(parser=None):
         ('schema', 'Validate cloud-config files for document schema',
          schema.get_parser, schema.handle_schema_args),
         (net_convert.NAME, net_convert.__doc__,
-         net_convert.get_parser, net_convert.handle_args)
+         net_convert.get_parser, net_convert.handle_args),
+        (render.NAME, render.__doc__,
+         render.get_parser, render.handle_args)
     ]
     for (subcmd, helpmsg, get_parser, handler) in subcmds:
         parser = subparsers.add_parser(subcmd, help=helpmsg)