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, 25 insertions, 0 deletions

diff --git a/cloudinit/cmd/devel/__init__.py b/cloudinit/cmd/devel/__init__.py
index e69de29b..3ae28b69 100644
--- a/cloudinit/cmd/devel/__init__.py
+++ b/cloudinit/cmd/devel/__init__.py
@@ -0,0 +1,25 @@
+# This file is part of cloud-init. See LICENSE file for license information.
+
+"""Common cloud-init devel commandline utility functions."""
+
+
+import logging
+
+from cloudinit import log
+from cloudinit.stages import Init
+
+
+def addLogHandlerCLI(logger, log_level):
+    """Add a commandline logging handler to emit messages to stderr."""
+    formatter = logging.Formatter('%(levelname)s: %(message)s')
+    log.setupBasicLogging(log_level, formatter=formatter)
+    return logger
+
+
+def read_cfg_paths():
+    """Return a Paths object based on the system configuration on disk."""
+    init = Init(ds_deps=[])
+    init.read_cfg()
+    return init.paths
+
+# vi: ts=4 expandtab