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, 10 insertions, 2 deletions

diff --git a/cloudinit/log.py b/cloudinit/log.py
index 1d75c9ff..5ae312ba 100644
--- a/cloudinit/log.py
+++ b/cloudinit/log.py
@@ -38,10 +38,18 @@ DEF_CON_FORMAT = '%(asctime)s - %(filename)s[%(levelname)s]: %(message)s'
 logging.Formatter.converter = time.gmtime
 
 
-def setupBasicLogging(level=DEBUG):
+def setupBasicLogging(level=DEBUG, formatter=None):
+    if not formatter:
+        formatter = logging.Formatter(DEF_CON_FORMAT)
     root = logging.getLogger()
+    for handler in root.handlers:
+        if hasattr(handler, 'stream') and hasattr(handler.stream, 'name'):
+            if handler.stream.name == '<stderr>':
+                handler.setLevel(level)
+                return
+    # Didn't have an existing stderr handler; create a new handler
     console = logging.StreamHandler(sys.stderr)
-    console.setFormatter(logging.Formatter(DEF_CON_FORMAT))
+    console.setFormatter(formatter)
     console.setLevel(level)
     root.addHandler(console)
     root.setLevel(level)