Jinja2 filters¶

The plugin registers five filters with NetBox's Jinja2 environment when it loads. They are available in Config Templates and in any other template NetBox renders, not only in requests made through the plugin's render endpoint.

Filters that produce device syntax take a vendor argument. Two values are recognized: "cisco" (the default) and "junos". Any other value falls back to Cisco syntax, so pass the vendor explicitly rather than feeding a platform slug straight in.

as_path_regex¶

as_path_regex(asn, vendor="cisco")

Returns a regular expression matching AS paths that start with asn.

ip_network¶

ip_network(prefix)

Parses a CIDR string and returns a dict with network, prefix_length, and netmask. Host bits are allowed and ignored.

Useful for platforms that want an address and mask instead of CIDR:

{% set net = "198.51.100.0/24" | ip_network %}
network {{ net.network }} mask {{ net.netmask }}

An invalid prefix raises an error and fails the render.

group_by¶

group_by(items, attr)

Groups a list of dicts or objects by a key or attribute and yields (value, items) pairs. Groups appear in the order their value is first seen, unlike Jinja's built-in groupby, which sorts. Items missing the attribute are grouped under None.

{% for relationship, group in sessions | group_by("relationship") %}
! {{ relationship or "unclassified" }}: {{ group | length }} sessions
{% endfor %}

to_community_list¶

to_community_list(value, name, vendor="cisco")

Renders one community value as a named community list.

{{ "64500:100" | to_community_list("CL-PEERS") }}:

ip community-list standard CL-PEERS permit 64500:100

{{ "64500:100" | to_community_list("CL-PEERS", "junos") }}:

policy-options {
    community CL-PEERS members 64500:100;
}

The Cisco form always emits a standard list with a permit action. The value is inserted as given and is not validated.

to_prefix_set¶

to_prefix_set(prefixes, name, vendor="cisco")

Renders a list of prefix entries as a named prefix list. Each entry is a dict with a prefix key and optional ge and le keys. An empty list returns an empty string.

Given:

{% set entries = [
  {"prefix": "192.0.2.0/24"},
  {"prefix": "198.51.100.0/22", "le": 24},
  {"prefix": "203.0.113.0/24", "ge": 25, "le": 28},
] %}

{{ entries | to_prefix_set("PL-AS64512") }}:

ip prefix-list PL-AS64512 seq 10 permit 192.0.2.0/24
ip prefix-list PL-AS64512 seq 20 permit 198.51.100.0/22 le 24
ip prefix-list PL-AS64512 seq 30 permit 203.0.113.0/24 ge 25 le 28

{{ entries | to_prefix_set("PL-AS64512", "junos") }}:

policy-options {
    prefix-list PL-AS64512 {
        192.0.2.0/24;
        198.51.100.0/22 upto /24;
        203.0.113.0/24 prefix-length-range /25-/28;
    }
}

Limitations to be aware of:

• The Cisco form always emits ip prefix-list with permit entries, numbered in steps of 10. It does not switch to ipv6 prefix-list for IPv6 prefixes.
• In the Junos form, an entry with ge but no le is rendered with an upper bound of /32. For IPv6 prefixes always give an explicit le.
• The render context does not include prefix list entries (see Configuration templating), so the input list has to come from elsewhere in your template or context data.

Overriding a filter¶

On NetBox 4.7 and later the filters are registered through NetBox's plugin filter registry, which ranks below the instance-level JINJA_FILTERS setting. Defining a filter of the same name there replaces the plugin's version. On NetBox releases before 4.7 the plugin writes its filters into the filter setting directly at startup and takes precedence.