Dynamic Path

Above are examples of static path, where all the path items are known and predefined beforehand, however, ttp supports dynamic path formation using match variable results for certain match variable names, i.e we have match variable name set to interface and correspondent match result would be Gi0/1, it is possible to use Gi0/1 as a path item.

Search for dynamic path item value happens using below sequence:

• First - group match results searched for path item value,

• Second - upper group results cache (latest values) used,

• Third - template variables searched for path item value,

• Last - group results discarded as invalid

Dynamic path items specified in group name attribute using “{{ item_name }}” format, there “{{ item_name }}” dynamically replaced with value found using above sequence.

Example-1

In this example interface variable match values will be used to substitute {{ interface }} dynamic path items.

Data:

interface Port-Chanel11
  description Storage
!
interface Loopback0
  description RID
  ip address 10.0.0.3/24
!
interface Vlan777
  description Management
  ip address 192.168.0.1/24
  vrf MGMT

Template:

<group name="interfaces.{{ interface }}">
interface {{ interface }}
  description {{ description }}
  ip address {{ ip }}/{{ mask }}
  vrf {{ vrf }}
</group>

Result:

[
    {
        "interfaces": {
            "Loopback0": {
                "description": "RID",
                "ip": "10.0.0.3",
                "mask": "24"
            },
            "Port-Chanel11": {
                "description": "Storage"
            },
            "Vlan777": {
                "description": "Management",
                "ip": "192.168.0.1",
                "mask": "24",
                "vrf": "MGMT"
            }
        }
    }
]

Because each path item is a string, and each item produced by spilling name attributes using ‘.’ dot character, it is possible to produce dynamic path there portions of path item will be dynamically substituted.

Data:

interface Port-Chanel11
  description Storage
!
interface Loopback0
  description RID
  ip address 10.0.0.3/24
!
interface Vlan777
  description Management
  ip address 192.168.0.1/24
  vrf MGMT

Template:

<group name="interfaces.cool_{{ interface }}_interface">
interface {{ interface }}
  description {{ description }}
  ip address {{ ip }}/{{ mask }}
  vrf {{ vrf }}
</group>

Result:

[
    {
        "interfaces": {
            "cool_Loopback0_interface": {
                "description": "RID",
                "ip": "10.0.0.3",
                "mask": "24"
            },
            "cool_Port-Chanel11_interface": {
                "description": "Storage"
            },
            "cool_Vlan777_interface": {
                "description": "Management",
                "ip": "192.168.0.1",
                "mask": "24",
                "vrf": "MGMT"
            }
        }
    }
]

Note

Substitution of dynamic path items happens using re.sub method without the limit set on the count of such a substitutions, e.g. if path item “cool_{{ interface }}_interface_{{ interface }}” and if interface value is “Gi0/1” resulted path item will be “cool_Gi0/1_interface_Gi0/1”

Nested hierarchies also supported with dynamic path, as if no variable found in the group match results ttp will try to find variable in the dynamic path cache or template variables.

Example-3

Data:

ucs-core-switch-1#show run | section bgp
router bgp 65100
  vrf CUST-1
    neighbor 59.100.71.193
      remote-as 65101
      description peer-1
      address-family ipv4 unicast
        route-map RPL-1-IMPORT-v4 in
        route-map RPL-1-EXPORT-V4 out
      address-family ipv6 unicast
        route-map RPL-1-IMPORT-V6 in
        route-map RPL-1-EXPORT-V6 out
    neighbor 59.100.71.209
      remote-as 65102
      description peer-2
      address-family ipv4 unicast
        route-map AAPTVRF-LB-BGP-IMPORT-V4 in
        route-map AAPTVRF-LB-BGP-EXPORT-V4 out

Template:

<vars>
hostname = "gethostname"
</vars>

<group name="{{ hostname }}.router.bgp.BGP_AS_{{ asn }}">
router bgp {{ asn }}
  <group name="vrfs.{{ vrf_name }}">
  vrf {{ vrf_name }}
    <group name="peers.{{ peer_ip }}">
    neighbor {{ peer_ip }}
      remote-as {{ peer_asn }}
      description {{ peer_description }}
      <group name="afi.{{ afi }}.unicast">
      address-family {{ afi }} unicast
        route-map {{ rpl_in }} in
        route-map {{ rpl_out }} out
      </group>
    </group>
   </group>
</group>

Result:

- ucs-core-switch-1:
    router:
      bgp:
        BGP_AS_65100:
          vrfs:
            CUST-1:
              peers:
                59.100.71.193:
                  afi:
                    ipv4:
                      unicast:
                        rpl_in: RPL-1-IMPORT-v4
                        rpl_out: RPL-1-EXPORT-V4
                    ipv6:
                      unicast:
                        rpl_in: RPL-1-IMPORT-V6
                        rpl_out: RPL-1-EXPORT-V6
                  peer_asn: '65101'
                  peer_description: peer-1
                59.100.71.209:
                  afi:
                    ipv4:
                      unicast:
                        rpl_in: RPL-2-IMPORT-V6
                        rpl_out: RPL-2-EXPORT-V6
                  peer_asn: '65102'
                  peer_description: peer-2