vyos.template: T7122: add Jinja2 clever function helper to read vyos.defaults

Add a new category if Jinja2 operands. We already have filters and tests, but
sometimes we would like to call a Python function without and data "|" piped
to it - that's what they call a clever-function.

{{ get_default_port(NAME) }} can be used to retrieve the value from
vyos.defaults.internal_ports[NAME] within Jinja2. We no longer need to extend
the dictionary with arbitrary data retrieved from vyos.defaults, we can now
simply register another clever-function to the Jinja2 backend.

1 files changed, 9 insertions, 0 deletions

diff --git a/src/tests/test_template.py b/src/tests/test_template.py
index 6377f6da5..7cae867a0 100644
--- a/src/tests/test_template.py
+++ b/src/tests/test_template.py
@@ -190,3 +190,12 @@ class TestVyOSTemplate(TestCase):
         for group_name, group_config in data['ike_group'].items():
             ciphers = vyos.template.get_esp_ike_cipher(group_config)
             self.assertIn(IKEv2_DEFAULT, ','.join(ciphers))
+
+    def test_get_default_port(self):
+        from vyos.defaults import internal_ports
+
+        with self.assertRaises(RuntimeError):
+            vyos.template.get_default_port('UNKNOWN')
+
+        self.assertEqual(vyos.template.get_default_port('certbot_haproxy'),
+                         internal_ports['certbot_haproxy'])