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, 14 insertions, 8 deletions

diff --git a/cloudinit/stages.py b/cloudinit/stages.py
index 8874d405..ef5c6996 100644
--- a/cloudinit/stages.py
+++ b/cloudinit/stages.py
@@ -17,10 +17,11 @@ from cloudinit.settings import (
 from cloudinit import handlers
 
 # Default handlers (used if not overridden)
-from cloudinit.handlers import boot_hook as bh_part
-from cloudinit.handlers import cloud_config as cc_part
-from cloudinit.handlers import shell_script as ss_part
-from cloudinit.handlers import upstart_job as up_part
+from cloudinit.handlers.boot_hook import BootHookPartHandler
+from cloudinit.handlers.cloud_config import CloudConfigPartHandler
+from cloudinit.handlers.jinja_template import JinjaTemplatePartHandler
+from cloudinit.handlers.shell_script import ShellScriptPartHandler
+from cloudinit.handlers.upstart_job import UpstartJobPartHandler
 
 from cloudinit.event import EventType
 
@@ -413,12 +414,17 @@ class Init(object):
             'datasource': self.datasource,
         })
         # TODO(harlowja) Hmmm, should we dynamically import these??
+        cloudconfig_handler = CloudConfigPartHandler(**opts)
+        shellscript_handler = ShellScriptPartHandler(**opts)
         def_handlers = [
-            cc_part.CloudConfigPartHandler(**opts),
-            ss_part.ShellScriptPartHandler(**opts),
-            bh_part.BootHookPartHandler(**opts),
-            up_part.UpstartJobPartHandler(**opts),
+            cloudconfig_handler,
+            shellscript_handler,
+            BootHookPartHandler(**opts),
+            UpstartJobPartHandler(**opts),
         ]
+        opts.update(
+            {'sub_handlers': [cloudconfig_handler, shellscript_handler]})
+        def_handlers.append(JinjaTemplatePartHandler(**opts))
         return def_handlers
 
     def _default_userdata_handlers(self):