instance-data: fallback to instance-data.json if sensitive is absent.

On cloud-init upgrade path from 18.3 to 18.4 cloud-init changed how
instance-data is written. Cloud-init changes instance-data.json from root
read-only to redacted world-readable content, and provided a separate
unredacted instance-data-sensitive.json which is read-only root.
Since instance-data is only rewritten from cache on
reboot, the query and render tools needed fallback to use the 'old'
instance-data.json if the new sensitive file isn't yet present.

This avoids error messages from tools about an absebt
/run/instance-data-sensitive.json file.

LP: #1798189

1 files changed, 18 insertions, 10 deletions

diff --git a/cloudinit/cmd/query.py b/cloudinit/cmd/query.py
index 7d2d4fe4..ff03de94 100644
--- a/cloudinit/cmd/query.py
+++ b/cloudinit/cmd/query.py
@@ -79,22 +79,30 @@ def handle_args(name, args):
     uid = os.getuid()
     if not all([args.instance_data, args.user_data, args.vendor_data]):
         paths = read_cfg_paths()
-    if not args.instance_data:
+    if args.instance_data:
+        instance_data_fn = args.instance_data
+    else:
+        redacted_data_fn = os.path.join(paths.run_dir, INSTANCE_JSON_FILE)
         if uid == 0:
-            default_json_fn = INSTANCE_JSON_SENSITIVE_FILE
+            sensitive_data_fn = os.path.join(
+                paths.run_dir, INSTANCE_JSON_SENSITIVE_FILE)
+            if os.path.exists(sensitive_data_fn):
+                instance_data_fn = sensitive_data_fn
+            else:
+                LOG.warning(
+                     'Missing root-readable %s. Using redacted %s instead.',
+                     sensitive_data_fn, redacted_data_fn)
+                instance_data_fn = redacted_data_fn
         else:
-            default_json_fn = INSTANCE_JSON_FILE  # World readable
-        instance_data_fn = os.path.join(paths.run_dir, default_json_fn)
+            instance_data_fn = redacted_data_fn
+    if args.user_data:
+        user_data_fn = args.user_data
     else:
-        instance_data_fn = args.instance_data
-    if not args.user_data:
         user_data_fn = os.path.join(paths.instance_link, 'user-data.txt')
+    if args.vendor_data:
+        vendor_data_fn = args.vendor_data
     else:
-        user_data_fn = args.user_data
-    if not args.vendor_data:
         vendor_data_fn = os.path.join(paths.instance_link, 'vendor-data.txt')
-    else:
-        vendor_data_fn = args.vendor_data
 
     try:
         instance_json = util.load_file(instance_data_fn)