jinja: provide and document jinja-safe key aliases in instance-data (SC-622) (#1123)

Allow #cloud-config and cloud-init query to use underscore-delimited
"jinja-safe" key aliases for any instance-data.json keys
containing jinja operator characters.

This provides a means to use Jinja's dot-notation instead of square brackets
and quoting to reference "unsafe" obtain attribute names.

Support for these aliased keys is available to both #cloud-config user-data and
`cloud-init query`.

For example #cloud-config alias access can look like:
  {{ ds.config.user_network_config }}

  - instead of -

  {{ ds.config["user.network-config"] }}

2 files changed, 44 insertions, 53 deletions

diff --git a/cloudinit/sources/DataSourceLXD.py b/cloudinit/sources/DataSourceLXD.py
index 55ae52a2..469707d2 100644
--- a/cloudinit/sources/DataSourceLXD.py
+++ b/cloudinit/sources/DataSourceLXD.py
@@ -190,19 +190,16 @@ class DataSourceLXD(sources.DataSource):
         self.metadata = _raw_instance_data_to_dict(
             "meta-data", self._crawled_metadata.get("meta-data")
         )
-        if LXD_SOCKET_API_VERSION in self._crawled_metadata:
-            config = self._crawled_metadata[LXD_SOCKET_API_VERSION].get(
-                "config", {}
+        config = self._crawled_metadata.get("config", {})
+        user_metadata = config.get("user.meta-data", {})
+        if user_metadata:
+            user_metadata = _raw_instance_data_to_dict(
+                "user.meta-data", user_metadata
+            )
+        if not isinstance(self.metadata, dict):
+            self.metadata = util.mergemanydict(
+                [util.load_yaml(self.metadata), user_metadata]
             )
-            user_metadata = config.get("user.meta-data", {})
-            if user_metadata:
-                user_metadata = _raw_instance_data_to_dict(
-                    "user.meta-data", user_metadata
-                )
-            if not isinstance(self.metadata, dict):
-                self.metadata = util.mergemanydict(
-                    [util.load_yaml(self.metadata), user_metadata]
-                )
         if "user-data" in self._crawled_metadata:
             self.userdata_raw = self._crawled_metadata["user-data"]
         if "network-config" in self._crawled_metadata:
@@ -304,7 +301,8 @@ def read_metadata(
         if metadata_only:
             return md  # Skip network-data, vendor-data, user-data
 
-        md[LXD_SOCKET_API_VERSION] = {
+        md = {
+            "_metadata_api_version": api_version,  # Document API version read
             "config": {},
             "meta-data": md["meta-data"]
         }
@@ -345,7 +343,7 @@ def read_metadata(
                 # Leave raw data values/format unchanged to represent it in
                 # instance-data.json for cloud-init query or jinja template
                 # use.
-                md[LXD_SOCKET_API_VERSION]["config"][cfg_key] = response.text
+                md["config"][cfg_key] = response.text
                 # Promote common CONFIG_KEY_ALIASES to top-level keys.
                 if cfg_key in CONFIG_KEY_ALIASES:
                     # Due to sort of config_routes, promote cloud-init.*
diff --git a/cloudinit/sources/tests/test_lxd.py b/cloudinit/sources/tests/test_lxd.py
index fc2a41df..a6e51f3b 100644
--- a/cloudinit/sources/tests/test_lxd.py
+++ b/cloudinit/sources/tests/test_lxd.py
@@ -42,15 +42,12 @@ LXD_V1_METADATA = {
     "network-config": NETWORK_V1,
     "user-data": "#cloud-config\npackages: [sl]\n",
     "vendor-data": "#cloud-config\nruncmd: ['echo vendor-data']\n",
-    "1.0": {
-        "meta-data": "instance-id: my-lxc\nlocal-hostname: my-lxc\n\n",
-        "config": {
-            "user.user-data":
-                "instance-id: my-lxc\nlocal-hostname: my-lxc\n\n",
-            "user.vendor-data":
-                "#cloud-config\nruncmd: ['echo vendor-data']\n",
-            "user.network-config": yaml.safe_dump(NETWORK_V1),
-        }
+    "config": {
+        "user.user-data":
+            "instance-id: my-lxc\nlocal-hostname: my-lxc\n\n",
+        "user.vendor-data":
+            "#cloud-config\nruncmd: ['echo vendor-data']\n",
+        "user.network-config": yaml.safe_dump(NETWORK_V1),
     }
 }
 
@@ -190,8 +187,10 @@ class TestReadMetadata:
                     "http://lxd/1.0/meta-data": "local-hostname: md\n",
                     "http://lxd/1.0/config": "[]",
                 },
-                {"1.0": {"config": {}, "meta-data": "local-hostname: md\n"},
-                 "meta-data": "local-hostname: md\n"},
+                {
+                    "_metadata_api_version": lxd.LXD_SOCKET_API_VERSION,
+                    "config": {}, "meta-data": "local-hostname: md\n"
+                },
                 ["[GET] [HTTP:200] http://lxd/1.0/meta-data",
                  "[GET] [HTTP:200] http://lxd/1.0/config"],
             ),
@@ -211,12 +210,10 @@ class TestReadMetadata:
                     "http://lxd/1.0/config/user.vendor-data": "",  # 404
                 },
                 {
-                    "1.0": {
-                        "config": {
-                            "user.custom1": "custom1",   # Not promoted
-                            "user.network-config": "net-config",
-                        },
-                        "meta-data": "local-hostname: md\n",
+                    "_metadata_api_version": lxd.LXD_SOCKET_API_VERSION,
+                    "config": {
+                        "user.custom1": "custom1",   # Not promoted
+                        "user.network-config": "net-config",
                     },
                     "meta-data": "local-hostname: md\n",
                     "network-config": "net-config",
@@ -250,15 +247,13 @@ class TestReadMetadata:
                     "http://lxd/1.0/config/user.vendor-data": "vendor-data",
                 },
                 {
-                    "1.0": {
-                        "config": {
-                            "user.custom1": "custom1",   # Not promoted
-                            "user.meta-data": "meta-data",
-                            "user.network-config": "net-config",
-                            "user.user-data": "user-data",
-                            "user.vendor-data": "vendor-data",
-                        },
-                        "meta-data": "local-hostname: md\n",
+                    "_metadata_api_version": lxd.LXD_SOCKET_API_VERSION,
+                    "config": {
+                        "user.custom1": "custom1",   # Not promoted
+                        "user.meta-data": "meta-data",
+                        "user.network-config": "net-config",
+                        "user.user-data": "user-data",
+                        "user.vendor-data": "vendor-data",
                     },
                     "meta-data": "local-hostname: md\n",
                     "network-config": "net-config",
@@ -303,19 +298,17 @@ class TestReadMetadata:
                         "cloud-init.vendor-data",
                 },
                 {
-                    "1.0": {
-                        "config": {
-                            "user.meta-data": "user.meta-data",
-                            "user.network-config": "user.network-config",
-                            "user.user-data": "user.user-data",
-                            "user.vendor-data": "user.vendor-data",
-                            "cloud-init.network-config":
-                                "cloud-init.network-config",
-                            "cloud-init.user-data": "cloud-init.user-data",
-                            "cloud-init.vendor-data":
-                                "cloud-init.vendor-data",
-                        },
-                        "meta-data": "local-hostname: md\n",
+                    "_metadata_api_version": lxd.LXD_SOCKET_API_VERSION,
+                    "config": {
+                        "user.meta-data": "user.meta-data",
+                        "user.network-config": "user.network-config",
+                        "user.user-data": "user.user-data",
+                        "user.vendor-data": "user.vendor-data",
+                        "cloud-init.network-config":
+                            "cloud-init.network-config",
+                        "cloud-init.user-data": "cloud-init.user-data",
+                        "cloud-init.vendor-data":
+                            "cloud-init.vendor-data",
                     },
                     "meta-data": "local-hostname: md\n",
                     "network-config": "cloud-init.network-config",