bgp: T6189: explicitly call vtysh to remove VRF L3VNI configuration

After e7bb65894 ("vrf: T6189: render FRR L3VNI configuration when creating VRF
instance") we need to ensure that the VRF L3VNI configuration is removed in FRR
prior to removing the BGP VRF instance.

The reason is [1] where FRR only allows VRF BGP instance to be removed when
there is NO VNI configured anymore.

1: https://github.com/FRRouting/frr/blob/064c3494527b9e84260410006768ed38e57e1de7/bgpd/bgp_vty.c#L1646-L1650
(cherry picked from commit 7b46172a4aecc714d929aecb8768ab82633de3ba)

1 files changed, 28 insertions, 18 deletions

diff --git a/src/conf_mode/protocols_bgp.py b/src/conf_mode/protocols_bgp.py
index 4df97d133..44409c0e3 100755
--- a/src/conf_mode/protocols_bgp.py
+++ b/src/conf_mode/protocols_bgp.py
@@ -31,6 +31,7 @@ from vyos.utils.dict import dict_search
 from vyos.utils.network import get_interface_vrf
 from vyos.utils.network import is_addr_assigned
 from vyos.utils.process import process_named_running
+from vyos.utils.process import call
 from vyos import ConfigError
 from vyos import frr
 from vyos import airbag
@@ -50,13 +51,8 @@ def get_config(config=None):
 
     # eqivalent of the C foo ? 'a' : 'b' statement
     base = vrf and ['vrf', 'name', vrf, 'protocols', 'bgp'] or base_path
-    bgp = conf.get_config_dict(
-        base,
-        key_mangling=('-', '_'),
-        get_first_key=True,
-        no_tag_node_value_mangle=True,
-        with_recursive_defaults=True,
-    )
+    bgp = conf.get_config_dict(base, key_mangling=('-', '_'),
+                               get_first_key=True, no_tag_node_value_mangle=True)
 
     bgp['dependent_vrfs'] = conf.get_config_dict(['vrf', 'name'],
                                                  key_mangling=('-', '_'),
@@ -75,22 +71,29 @@ def get_config(config=None):
     if vrf:
         bgp.update({'vrf' : vrf})
         # We can not delete the BGP VRF instance if there is a L3VNI configured
+        # FRR L3VNI must be deleted first otherwise we will see error:
+        # "FRR error: Please unconfigure l3vni 3000"
         tmp = ['vrf', 'name', vrf, 'vni']
-        if conf.exists(tmp):
-            bgp.update({'vni' : conf.return_value(tmp)})
+        if conf.exists_effective(tmp):
+            bgp.update({'vni' : conf.return_effective_value(tmp)})
         # We can safely delete ourself from the dependent vrf list
         if vrf in bgp['dependent_vrfs']:
             del bgp['dependent_vrfs'][vrf]
 
-    bgp['dependent_vrfs'].update({'default': {'protocols': {
-        'bgp': conf.get_config_dict(base_path, key_mangling=('-', '_'),
-                                    get_first_key=True,
-                                    no_tag_node_value_mangle=True)}}})
+        bgp['dependent_vrfs'].update({'default': {'protocols': {
+            'bgp': conf.get_config_dict(base_path, key_mangling=('-', '_'),
+                                        get_first_key=True,
+                                        no_tag_node_value_mangle=True)}}})
+
     if not conf.exists(base):
         # If bgp instance is deleted then mark it
         bgp.update({'deleted' : ''})
         return bgp
 
+    # We have gathered the dict representation of the CLI, but there are default
+    # options which we need to update into the dictionary retrived.
+    bgp = conf.merge_defaults(bgp, recursive=True)
+
     # We also need some additional information from the config, prefix-lists
     # and route-maps for instance. They will be used in verify().
     #
@@ -242,10 +245,6 @@ def verify(bgp):
                 if verify_vrf_as_import(bgp['vrf'], tmp_afi, bgp['dependent_vrfs']):
                     raise ConfigError(f'Cannot delete VRF instance "{bgp["vrf"]}", ' \
                                       'unconfigure "import vrf" commands!')
-            # We can not delete the BGP instance if a L3VNI instance exists
-            if 'vni' in bgp:
-                raise ConfigError(f'Cannot delete VRF instance "{bgp["vrf"]}", ' \
-                                  f'unconfigure VNI "{bgp["vni"]}" first!')
         else:
             # We are running in the default VRF context, thus we can not delete
             # our main BGP instance if there are dependent BGP VRF instances.
@@ -254,7 +253,11 @@ def verify(bgp):
                     if vrf != 'default':
                         if dict_search('protocols.bgp', vrf_options):
                             raise ConfigError('Cannot delete default BGP instance, ' \
-                                              'dependent VRF instance(s) exist!')
+                                              'dependent VRF instance(s) exist(s)!')
+                        if 'vni' in vrf_options:
+                            raise ConfigError('Cannot delete default BGP instance, ' \
+                                              'dependent L3VNI exists!')
+
         return None
 
     if 'system_as' not in bgp:
@@ -607,6 +610,13 @@ def generate(bgp):
     return None
 
 def apply(bgp):
+    if 'deleted' in bgp:
+        # We need to ensure that the L3VNI is deleted first.
+        # This is not possible with old config backend
+        # priority bug
+        if {'vrf', 'vni'} <= set(bgp):
+            call('vtysh -c "conf t" -c "vrf {vrf}" -c "no vni {vni}"'.format(**bgp))
+
     bgp_daemon = 'bgpd'
 
     # Save original configuration prior to starting any commit actions