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, 8 insertions, 4 deletions

diff --git a/tests/integration_tests/modules/test_jinja_templating.py b/tests/integration_tests/modules/test_jinja_templating.py
index 35b8ee2d..fe8eff1a 100644
--- a/tests/integration_tests/modules/test_jinja_templating.py
+++ b/tests/integration_tests/modules/test_jinja_templating.py
@@ -11,6 +11,7 @@ USER_DATA = """\
 runcmd:
   - echo {{v1.local_hostname}} > /var/tmp/runcmd_output
   - echo {{merged_cfg._doc}} >> /var/tmp/runcmd_output
+  - echo {{v1['local-hostname']}} >> /var/tmp/runcmd_output
 """
 
 
@@ -18,13 +19,16 @@ runcmd:
 def test_runcmd_with_variable_substitution(client: IntegrationInstance):
     """Test jinja substitution.
 
-    Ensure we can also substitute variables from instance-data-sensitive
-    LP: #1931392
+    Ensure underscore-delimited aliases exist for hyphenated key and
+    we can also substitute variables from instance-data-sensitive
+    LP: #1931392.
     """
+    hostname = client.execute('hostname').stdout.strip()
     expected = [
-        client.execute('hostname').stdout.strip(),
+        hostname,
         ('Merged cloud-init system config from /etc/cloud/cloud.cfg and '
-            '/etc/cloud/cloud.cfg.d/')
+            '/etc/cloud/cloud.cfg.d/'),
+        hostname
     ]
     output = client.read_from_file('/var/tmp/runcmd_output')
     verify_ordered_items_in_text(expected, output)