Custom jinja filter for render config

[andershagman]

Have started to use the render config system and it works as it should.
BUT, jinja is not always the best languish for the job.
It doesn´t handle global variables and lack normal string feature like split.

My problem was to convert a list of VLANs to Cisco style.

From this:

interface GigabitEthernet1/0/1
 switchport trunk allowed vlan 1393,1394,1395,1396,1397,1398,1399,1409,3393,3394,3395,3396,3397,3398,3399,3409

To this:

interface GigabitEthernet1/0/1
 switchport trunk allowed vlan 1393-1399, 1409, 3393-3399, 3409

I couldn´t find any solution for this in jinja, so I made a jinja filter in python and added it to the configuration.py file

def list_to_ranges(lst):
    sorted_lst = sorted(lst)
    ranges = []
    start = sorted_lst[0]
    end = sorted_lst[0]

    for num in sorted_lst[1:]:
        if num == end + 1:
            end = num
        else:
            if start == end:
                ranges.append(str(start))
            else:
                ranges.append(f"{start}-{end}")
            start = num
            end = num

    if start == end:
        ranges.append(str(start))
    else:
        ranges.append(f"{start}-{end}")

    return ', '.join(ranges)

JINJA2_FILTERS = {
    'list_to_ranges': list_to_ranges,
}

Is there a better way to add filters or should we have a more scaleable way to do this?

[mtinberg]

I've only used Jinja2 within Ansible so I don't know which behaviors are built-in and which are Ansible-specific, but AFAIK you can call python string methods on jinja strings[1] eg {{ foo.split('-')[0] }}​ and Ansible has a jinja filter for this specific case[2] to output IOS-style VLAN lists which you may be able to use as a reference if the licensing for ansible.netcommon allows it. [1] https://jinja.palletsprojects.com/en/3.1.x/templates/#python-methods [2] https://docs.ansible.com/ansible/latest/playbook_guide/playbooks_filters.html#network-vlan-filters — Mark Tinberg ***@***.***> Division of Information Technology-Network Services University of Wisconsin-Madison

…

________________________________ From: andershagman ***@***.***> Sent: Wednesday, July 26, 2023 9:51 AM To: netbox-community/netbox ***@***.***> Cc: Subscribed ***@***.***> Subject: [netbox-community/netbox] Custom jinja filter for render config (Discussion #13273) Have started to use the render config system and it works as it should. BUT, jinja is not always the best languish for the job. It doesn´t handle global variables and lack normal string feature like split. My problem was to convert a list of VLANs to Cisco style. From this: interface GigabitEthernet1/0/1 switchport trunk allowed vlan 1393,1394,1395,1396,1397,1398,1399,1409,3393,3394,3395,3396,3397,3398,3399,3409 To this: interface GigabitEthernet1/0/1 switchport trunk allowed vlan 1393-1399, 1409, 3393-3399, 3409 I couldn´t find any solution for this in jinja, so I made a jinja filter in python and added it to the configuration.py file def list_to_ranges(lst): sorted_lst = sorted(lst) ranges = [] start = sorted_lst[0] end = sorted_lst[0] for num in sorted_lst[1:]: if num == end + 1: end = num else: if start == end: ranges.append(str(start)) else: ranges.append(f"{start}-{end}") start = num end = num if start == end: ranges.append(str(start)) else: ranges.append(f"{start}-{end}") return ', '.join(ranges) JINJA2_FILTERS = { 'list_to_ranges': list_to_ranges, } Is there a better way to add filters or should we have a more scaleable way to to this? — Reply to this email directly, view it on GitHub<#13273>, or unsubscribe<https://github.com/notifications/unsubscribe-auth/AAS7UMZZPZ2J4UOAPUIPFA3XSEVFVANCNFSM6AAAAAA2YW2ZFQ>. You are receiving this because you are subscribed to this thread.Message ID: ***@***.***>

[andershagman]

Good to know about string and so on regarding using python. As a beginner you do not test everything.
I have used netcommon before but that was outside Netbox, and I had to install Ansible to make it work.
I don´t use Ansible but Nornir.

So the question remains, how to import external filter into Netbox?

[abhi1693]

https://docs.netbox.dev/en/stable/configuration/system/#jinja2_filters

[andershagman]

Yes, that is how I did it. But if you have 30+ filters do we have a better way to add filters, like pointing to a directory or an import statement?

[kkthxbye-code]

I mean the configuration.py file is just a regular python file so you can do whatever you want. Like create $NETBOXROOT/netbox/local/filters.py with this content:

def test_filter(value):
    return value + 'test'

Then in your config file:

from local import filters

JINJA2_FILTERS = {
    'test_filter': filters.test_filter,
}

I don't see why this wouldn't scale fine. Just make sure that if you need to import anything from netbox, that you do it inside the method.

[andershagman]

So a solution like this could do?

$NETBOXROOT/netbox/local/filters.py

def cf_filter1(s):
    result = s
    return result

def cf_filter2(s):
    result = s
    return result

def cf_filter3(s):
    result = s
    return result

def import_filters():
    cf_filter = {}
    func_list = globals()

    for func in func_list:
        if "cf_" in func:
            cf_filter[func] = f'filters.{func}'

    return cf_filter

if __name__ == "__main__":
    print(import_filters())

And the configuration.py file

from local import filters

JINJA2_FILTERS  = filters.import_filters()