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"] }}

1 files changed, 32 insertions, 39 deletions

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",