static: T5398: do not mangle interface names in FRR

[jvoss]

Change Summary

This PR resolves an issue when configuring static routes involving interfaces containing a - in the name. When rendered to FRR, the interface is mangled to an underscore _. This is most noticeable when creating static VRF-leaked routes for container networks:

pod-TEST becomes pod_TEST

# VyOS
container {
  name TEST {
     image ubuntu:20.04
     network TEST {
     }
  }
  network TEST {
     prefix 192.168.1.0/24
  }
}
vrf {
  name TEST {
    protocols {
        static {
             route 192.168.1.0/24 {
                 interface pod-TEST {
                     vrf default
                 }
             }
         }
    }
  }

}

# FRR rendered configuration
!
vrf TEST
 ip route 192.168.1.0/24 pod_TEST nexthop-vrf default
exit-vrf
!

No static route is installed into the table due to the mismatching interface name:

jvoss@test-R1:~$ show ip route vrf TEST static
jvoss@test-R1:~$ 

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Code style update (formatting, renaming)
• Refactoring (no functional changes)
• Migration from an old Vyatta component to vyos-1x, please link to related PR inside obsoleted component
• Other (please describe):

Related Task(s)

• https://vyos.dev/T5398

Component(s) name

• protocols static

Proposed changes

Update the static configuration retrieval in protocols_static.py to not mangle node values by adding the no_tag_node_value_mangle=True option.

How to test

Perform the configuration changes as documented in the change summary. However after this change is applied and vyos-configd is restarted the interface name is no longer mangled:

# FRR rendered configuration
!
vrf TEST
 ip route 192.168.1.0/24 pod-TEST nexthop-vrf default
exit-vrf
!

The route is also installed into the routing table:

jvoss@test-R1:~$ show ip route vrf TEST static
Codes: K - kernel route, C - connected, S - static, R - RIP,
       O - OSPF, I - IS-IS, B - BGP, E - EIGRP, N - NHRP,
       T - Table, v - VNC, V - VNC-Direct, A - Babel, F - PBR,
       f - OpenFabric,
       > - selected route, * - FIB route, q - queued, r - rejected, b - backup
       t - trapped, o - offload failure

VRF TEST:
S>* 192.168.1.0/24 [1/0] is directly connected, pod-TEST (vrf default), weight 1, 00:00:45

Checklist:

• I have read the CONTRIBUTING document
• I have linked this PR to one or more Phabricator Task(s)
• I have run the components SMOKETESTS if applicable
• My commit headlines contain a valid Task id
• My change requires a change to the documentation
• I have updated the documentation accordingly