ospf: T9448: do not render metric-type when it is the default

With metric-type 2 (the CLI default), every FRR reload deletes and
re-adds "default-information originate" and every "redistribute" line
under "router ospf". ospfd flushes the Type-5 LSAs on the delete and
re-originates them right after, so neighbours can briefly lose the
external routes on commits that do not touch OSPF.

ospfd and ospf6d (for redistribute) write "metric-type 1" back to the
running config and print nothing for type 2, their default. The
templates render "metric-type 2", so frr-reload sees a different line
on every reload.

frrender now adds the XML default of metric-type to the OSPF and OSPFv3
dicts as xml_default_metric_type, for the default and every VRF
instance. The templates render metric-type only when it differs from
that default, so the generated config matches what FRR prints back.
OSPFv3 default-information keeps rendering metric-type, as ospf6d
prints it for both types.

Add smoketests that read the generated config and vtysh for types 2,
1 and back to 2. Rename the "ptotocol" loop variable in
test_protocols_ospf.py to "protocol", which the typos check flags on
any change to this file.

1 files changed, 13 insertions, 0 deletions

diff --git a/python/vyos/frrender.py b/python/vyos/frrender.py
index 371ea95b5..7d1401d2c 100644
--- a/python/vyos/frrender.py
+++ b/python/vyos/frrender.py
@@ -120,6 +120,12 @@ def get_frrender_dict(conf: Config, argv=None) -> dict:
         # options which we need to update into the dictionary retrieved.
         default_values = conf.get_config_defaults(path, key_mangling=('-', '_'),
                                                   get_first_key=True, recursive=True)
+        # The XML default of metric-type (shared by default-information and
+        # redistribute) is added to the dict, the template cannot query it
+        # while rendering.
+        xml_default_metric_type = dict_search(
+            'default_information.originate.metric_type', default_values
+        )
 
         # We have to cleanup the default dict, as default values could enable features
         # which are not explicitly enabled on the CLI. Example: default-information
@@ -151,6 +157,7 @@ def get_frrender_dict(conf: Config, argv=None) -> dict:
                 del default_values['interface'][interface]['dead_interval']
 
         ospf = config_dict_merge(default_values, ospf)
+        ospf['xml_default_metric_type'] = xml_default_metric_type
         return ospf
 
     def dict_helper_ospfv3_defaults(ospfv3, path):
@@ -158,6 +165,11 @@ def get_frrender_dict(conf: Config, argv=None) -> dict:
         # options which we need to update into the dictionary retrieved.
         default_values = conf.get_config_defaults(path, key_mangling=('-', '_'),
                                                   get_first_key=True, recursive=True)
+        # The XML default of metric-type is added to the dict, the template
+        # cannot query it while rendering.
+        xml_default_metric_type = dict_search(
+            'default_information.originate.metric_type', default_values
+        )
 
         # We have to cleanup the default dict, as default values could enable features
         # which are not explicitly enabled on the CLI. Example: default-information
@@ -179,6 +191,7 @@ def get_frrender_dict(conf: Config, argv=None) -> dict:
 
         # merge in remaining default values
         ospfv3 = config_dict_merge(default_values, ospfv3)
+        ospfv3['xml_default_metric_type'] = xml_default_metric_type
         return ospfv3
 
     def dict_helper_pim_defaults(pim, path):