Netbox Create Prefix Task

task api name: create_prefix

Task to create next available prefix of given prefix length within parent prefix or get existing prefix. By default prefix length is 30 resulting in ptp subnet allocation.

Netbox service create_prefix task integrated with Nornir service and can be called using netbox.create_prefix Jinja2 filter, allowing to allocate prefixes in Netbox on the fly while rendering configuration templates.

Warning

Netbox create_prefix task uses prefix description argument to deduplicate prefixes, calls to create_prefix task should contain identical prefix description value for same prefix.

Branching Support

Create Prefix task is branch aware and can create IP addresses within the branch. Netbox Branching Plugin need to be installed on Netbox instance.

NORFAB Netbox Create Prefix Command Shell Reference

NorFab shell supports these command options for Netbox create_prefix task:

nf#man tree netbox.create.prefix
root
└── netbox:    Netbox service
    └── create:    Create objects in Netbox
            ├── instance:    Netbox instance name to target
            ├── dry-run:    Do not commit to database
            ├── *parent:    Parent prefix to allocate new prefix from
            ├── *description:    Description for new prefix
            ├── prefixlen:    The prefix length of the new prefix, default '30'
            ├── vrf:    Name of the VRF to associate with the prefix
            ├── tags:    List of tags to assign to the prefix
            ├── tenant:    Name of the tenant to associate with the prefix
            ├── comments:    Comments for the prefix
            ├── role:    Role to assign to the prefix
            ├── site:    Name of the site to associate with the prefix
            ├── status:    Status of the prefix
            ├── branch:    Branching plugin branch name to use
            ├── timeout:    Job timeout
            ├── workers:    Filter worker to target, default 'any'
            ├── verbose-result:    Control output details, default 'False'
            └── progress:    Display progress events, default 'True'
nf#

Python API Reference

Creates a new IP prefix in NetBox or updates an existing one.

Parameters:

Name	Type	Description	Default
parent	Union[str, dict]	Parent prefix to allocate new prefix from, could be: IPv4 prefix string e.g. 10.0.0.0/24 IPv6 prefix string e.g. 2001::/64 Prefix description string to filter by Dictionary with prefix filters for pynetbox prefixes.get method e.g. {"prefix": "10.0.0.0/24", "site__name": "foo"}	required
description	str	Description for the new prefix, prefix description used for deduplication to source existing prefixes.	None
prefixlen	int	The prefix length of the new prefix to create, by default allocates next available /30 point-to-point prefix.	30
vrf	str	Name of the VRF to associate with the prefix.	None
tags	Union[None, list]	List of tags to assign to the prefix.	None
tenant	str	Name of the tenant to associate with the prefix.	None
comments	str	Comments for the prefix.	None
role	str	Role to assign to the prefix.	None
site	str	Name of the site to associate with the prefix.	None
status	str	Status of the prefix.	None
instance	Union[None, str]	NetBox instance identifier.	None
dry_run	bool	If True, simulates the creation without making changes.	False
branch	str	Branch name to use, need to have branching plugin installed, automatically creates branch if it does not exist in Netbox.	None

Returns:

Name	Type	Description
Result	Result	An object containing the outcome, including status, details of the prefix, and resources used.

Source code in norfab\workers\netbox_worker.py

@Task(
    input=CreatePrefixInput,
    fastapi={"methods": ["POST"], "schema": NetboxFastApiArgs.model_json_schema()},
)
def create_prefix(
    self,
    job: Job,
    parent: Union[str, dict],
    description: str = None,
    prefixlen: int = 30,
    vrf: str = None,
    tags: Union[None, list] = None,
    tenant: str = None,
    comments: str = None,
    role: str = None,
    site: str = None,
    status: str = None,
    instance: Union[None, str] = None,
    dry_run: bool = False,
    branch: str = None,
) -> Result:
    """
    Creates a new IP prefix in NetBox or updates an existing one.

    Args:
        parent (Union[str, dict]): Parent prefix to allocate new prefix from, could be:

            - IPv4 prefix string e.g. 10.0.0.0/24
            - IPv6 prefix string e.g. 2001::/64
            - Prefix description string to filter by
            - Dictionary with prefix filters for `pynetbox` prefixes.get method
                e.g. `{"prefix": "10.0.0.0/24", "site__name": "foo"}`

        description (str): Description for the new prefix, prefix description used for
            deduplication to source existing prefixes.
        prefixlen (int, optional): The prefix length of the new prefix to create, by default
            allocates next available /30 point-to-point prefix.
        vrf (str, optional): Name of the VRF to associate with the prefix.
        tags (Union[None, list], optional): List of tags to assign to the prefix.
        tenant (str, optional): Name of the tenant to associate with the prefix.
        comments (str, optional): Comments for the prefix.
        role (str, optional): Role to assign to the prefix.
        site (str, optional): Name of the site to associate with the prefix.
        status (str, optional): Status of the prefix.
        instance (Union[None, str], optional): NetBox instance identifier.
        dry_run (bool, optional): If True, simulates the creation without making changes.
        branch (str, optional): Branch name to use, need to have branching plugin installed,
            automatically creates branch if it does not exist in Netbox.

    Returns:
        Result: An object containing the outcome, including status, details of the prefix, and resources used.
    """
    instance = instance or self.default_instance
    changed = {}
    ret = Result(
        task=f"{self.name}:create_prefix",
        result={},
        resources=[instance],
        diff=changed,
    )
    tags = tags or []
    nb_prefix = None
    nb = self._get_pynetbox(instance, branch=branch)

    job.event(
        f"Processing prefix create request within '{parent}' for '/{prefixlen}' subnet"
    )

    # source parent prefix from Netbox
    if isinstance(parent, str):
        # check if parent prefix is IP network or description
        try:
            _ = ipaddress.ip_network(parent)
            is_network = True
        except:
            is_network = False
        if is_network is True and vrf:
            parent_filters = {"prefix": parent, "vrf__name": vrf}
        elif is_network is True:
            parent_filters = {"prefix": parent}
        elif is_network is False and vrf:
            parent_filters = {"description": parent, "vrf__name": vrf}
        elif is_network is False:
            parent_filters = {"description": parent}
    nb_parent_prefix = nb.ipam.prefixes.get(**parent_filters)
    if not nb_parent_prefix:
        raise NetboxAllocationError(
            f"Unable to source parent prefix from Netbox - {parent}"
        )

    # check that parent vrf and new prefix vrf are same
    if vrf and str(nb_parent_prefix.vrf) != vrf:
        raise NetboxAllocationError(
            f"Parent prefix vrf '{nb_parent_prefix.vrf}' not same as requested child prefix vrf '{vrf}'"
        )

    # try to source existing prefix from netbox
    prefix_filters = {}
    if vrf:
        prefix_filters["vrf__name"] = vrf
    if site:
        prefix_filters["site__name"] = site
    if description:
        prefix_filters["description"] = description
    try:
        if prefix_filters:
            nb_prefix = nb.ipam.prefixes.get(
                within=nb_parent_prefix.prefix, **prefix_filters
            )
    except Exception as e:
        raise NetboxAllocationError(
            f"Failed to source existing prefix from Netbox using filters '{prefix_filters}', error: {e}"
        )

    # create new prefix
    if not nb_prefix:
        job.event(f"Creating new '/{prefixlen}' prefix within '{parent}' prefix")
        # execute dry run on new prefix
        if dry_run is True:
            nb_prefixes = nb_parent_prefix.available_prefixes.list()
            if not nb_prefixes:
                raise NetboxAllocationError(
                    f"Parent prefix '{parent}' has no child prefixes available"
                )
            for pfx in nb_prefixes:
                # parent prefix empty, can use first subnet as a child prefix
                if pfx.prefix == nb_parent_prefix.prefix:
                    nb_prefix = (
                        nb_parent_prefix.prefix.split("/")[0] + f"/{prefixlen}"
                    )
                    break
                # find child prefix by prefixlenght
                elif str(pfx).endswith(f"/{prefixlen}"):
                    nb_prefix = str(pfx)
                    break
            else:
                raise NetboxAllocationError(
                    f"Parent prefix '{parent}' has no child prefixes available with '/{prefixlen}' prefix length"
                )
            ret.status = "unchanged"
            ret.dry_run = True
            ret.result = {
                "prefix": nb_prefix,
                "description": description,
                "parent": nb_parent_prefix.prefix,
                "vrf": vrf,
                "site": site,
            }
            # add branch to results
            if branch is not None:
                ret.result["branch"] = branch
            return ret
        # create new prefix
        else:
            try:
                nb_prefix = nb_parent_prefix.available_prefixes.create(
                    {"prefix_length": prefixlen}
                )
            except Exception as e:
                raise NetboxAllocationError(
                    f"Failed creating child prefix of '/{prefixlen}' prefix length "
                    f"within parent prefix '{str(nb_parent_prefix)}', error: {e}"
                )
        job.event(f"Created new '{nb_prefix}' prefix within '{parent}' prefix")
        ret.status = "created"
    else:
        # check existing prefix length matching requested length
        if not nb_prefix.prefix.endswith(f"/{prefixlen}"):
            raise NetboxAllocationError(
                f"Found existing child prefix '{nb_prefix.prefix}' with mismatch "
                f"requested prefix length '/{prefixlen}'"
            )
        job.event(f"Using existing prefix {nb_prefix}")

    # update prefix parameters
    if description and description != nb_prefix.description:
        changed["description"] = {"-": str(nb_prefix.description), "+": description}
        nb_prefix.description = description
    if vrf and vrf != str(nb_prefix.vrf):
        changed["vrf"] = {"-": str(nb_prefix.vrf), "+": vrf}
        nb_prefix.vrf = {"name": vrf}
    if tenant and tenant != str(nb_prefix.tenant):
        changed["tenant"] = {
            "-": str(nb_prefix.tenant) if nb_prefix.tenant else None,
            "+": tenant,
        }
        nb_prefix.tenant = {"name": tenant}
    if site and str(nb_prefix.scope) != site:
        nb_site = nb.dcim.sites.get(name=site)
        if not nb_site:
            raise NetboxAllocationError(f"Failed to get '{site}' site from Netbox")
        changed["site"] = {
            "-": str(nb_prefix.scope) if nb_prefix.scope else None,
            "+": nb_site.name,
        }
        nb_prefix.scope_type = "dcim.site"
        nb_prefix.scope_id = nb_site.id
    if status and status.lower() != nb_prefix.status:
        changed["status"] = {"-": str(nb_prefix.status), "+": status.title()}
        nb_prefix.status = status.lower()
    if comments and comments != nb_prefix.comments:
        changed["comments"] = {"-": str(nb_prefix.comments), "+": comments}
        nb_prefix.comments = comments
    if role and role != nb_prefix.role:
        changed["role"] = {"-": str(nb_prefix.role), "+": role}
        nb_prefix.role = {"name": role}
    existing_tags = [str(t) for t in nb_prefix.tags]
    if tags and not any(t in existing_tags for t in tags):
        changed["tags"] = {
            "-": existing_tags,
            "+": [t for t in tags if t not in existing_tags] + existing_tags,
        }
        for t in tags:
            if t not in existing_tags:
                nb_prefix.tags.append({"name": t})

    # save prefix into Netbox
    if dry_run:
        ret.status = "unchanged"
        ret.dry_run = True
        ret.diff = changed
    elif changed:
        ret.diff = changed
        nb_prefix.save()
        if ret.status != "created":
            ret.status = "updated"
    else:
        ret.status = "unchanged"

    # source vrf name
    vrf_name = None
    if nb_prefix.vrf:
        if isinstance(nb_prefix.vrf, dict):
            vrf_name = nb_prefix.vrf["name"]
        else:
            vrf_name = nb_prefix.vrf.name

    # form and return results
    ret.result = {
        "prefix": nb_prefix.prefix,
        "description": nb_prefix.description,
        "vrf": vrf_name,
        "site": str(nb_prefix.scope) if nb_prefix.scope else site,
        "parent": nb_parent_prefix.prefix,
    }
    # add branch to results
    if branch is not None:
        ret.result["branch"] = branch

    return ret