select a list of interfaces with Python CISCOCONFPARSE and regex

Question

I use a double loop to select all interfaces GigabitEthernet1/0/1 to 1/0/16 and 2/0/1 to 2/0/16 using efficient tool CISCOCONFPARSE : here is the example, that works :

CONFIG_PARSED = CiscoConfParse(CONFIG)
for i in range(1,3):
    for j in range(1,17):
        INT = CONFIG_PARSED.find_objects('^interface GigabitEthernet'+str(i)+'/0/'+str(j)+'$')

Question : Is there a way to do the same using a simple loop with a regex such as my incorrect example below ?

for INT in CONFIG_PARSED.find_objects('^interface GigabitEthernet[1-2]/0/[1-16]$')

This other example below is a valid regex, but does not allow to select 1 to 16 numbers :

for INT in CONFIG_PARSED.find_objects('^interface GigabitEthernet[1-2]/0/')

thanks for any help

Answer 1

You essentially have two options...

OPTION A: Parse port numbers yourself, using stable and supported CiscoConfParse code...

import re
from ciscoconfparse import CiscoConfParse

CONFIG_PARSED = CiscoConfParse(CONFIG)
intf_rgx = re.compile(r'interface GigabitEthernet(\d+)\/(\d+)\/(\d+)$')
for obj in CONFIG_PARSED.find_objects('^interface GigabitEthernet'):
    mm = intf_rgx.search(obj.text))
    card = int(mm.group(1))
    port = int(mm.group(3))
    if card>2:
        continue
    if port>16:
        continue
    ## Do something here with obj

OPTION B: Offload port number parsing to CiscoConfParse's alpha-quality (as of version 1.1.5) port number parser...

import re
from ciscoconfparse import CiscoConfParse

CONFIG_PARSED = CiscoConfParse(CONFIG, factory=True)
for obj in CONFIG_PARSED.find_objects('^interface GigabitEthernet'):
    card = obj.ordinal_list[0]
    port = obj.ordinal_list[-1]
    if card>2:
        continue
    if port>16:
        continue
    ## Do something here with obj

FYI, obj.ordinal_list returns a python list of integers representing the card, slot and port number of the interface. For instance ordinal_list for "GigabitEthernet2/0/11" is [2, 0, 11]. You must use version 1.1.5 (or higher) and parse with factory=True to get ordinal_list.

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DON'T DO THIS:

The example you provided is truly bad from a performance perspective, because find_objects() walks the entire Cisco IOS configuration, start to finish looking for the regex provided. In case it isn't obvious, walking the entire Cisco IOS configuration 32 different times with find_objects() is very slow.

CONFIG_PARSED = CiscoConfParse(CONFIG)
for i in range(1,3):
    for j in range(1,17):
        INT = CONFIG_PARSED.find_objects('^interface GigabitEthernet'+str(i)+'/0/'+str(j)+'$')