Automatically set Asset Tag on created Devices

[MalteMagnussen]

When a new dcim.device is created in our NetBox, I'd like the Asset Tag to be set to OC${self.manufacturer.id}${self.serial_number}

I think I can maybe use an "Event Rule" to trigger a "Script" to do this, but the documentation is not very clear on how this works.

I'd assume that if I create an Event Rule that triggers when a Device is created, it would send all info about the created device to the script, but that seems to not be the case upon further reading.

What I want is basically this logic:

when dcim.device is created:
  device.asset_tag = f"OC{device.manufacturer.id}{device.serial_number}"

How can I most easily achieve this?

The docs are not clear at all about what info is sent from the Event Rule to the Script.

Also not clear at all about what is possible inside the script.

Like here fx, I would assume that I can pass the created device via "Action Data" but there is just no info about Action Data really: https://netboxlabs.com/docs/netbox/en/stable/models/extras/eventrule/

All it says is "An optional dictionary of JSON data to pass when executing the rule. This can be useful to include additional context data, e.g. when transmitting a webhook."

Docs I have read:

• https://netboxlabs.com/docs/netbox/en/stable/customization/custom-scripts/
• https://netboxlabs.com/blog/getting-started-with-netbox-custom-scripts/
• https://github.com/netbox-community/netbox-zero-to-hero/blob/main/modules/11-custom-scripts/11-custom-scripts.md
• https://www.youtube.com/watch?v=jxsFwyMk18k
• https://netboxlabs.com/docs/netbox/en/stable/models/extras/eventrule/

[ziggekatten]

The Event Rule sends an dict with some info (the "data" object/variable), where the object id of the device is one.

An example to attach to an Create Event Rule:

from dcim.models import Device
class SetAssetTag(Script):
    class Meta:
        name = "Event trigger that sets Asset tag"
        description = "Event trigger that sets Asset tag" 
        commit_default = True
        scheduling_enabled = False

    def run(self, data, commit):
        # If run through UI this is empty and just returns
        if data == {}:
            return
        #log the Event Rule data
        self.log_info(data)
        device = Device.objects.get(id=data['id'])
        device.snapshot()
        device.asset_tag = f"OC{device.device_type.manufacturer.id}{device.serial}"
        device.save() 

[MalteMagnussen]

@ziggekatten - Thank you.

How did you learn that fx device = Device.objects.get(id=data['id']) is something you can do?

And where do the logs show up? Where can I find them?

ChatGPT suggested this, but I imagined it was just hallucinating things:

It also uses "pk" instead, which I have no idea what that means.

from dcim.models import Device
from extras.scripts import Script


class SetAssetTag(Script):
    class Meta:
        name = "Set Asset Tag on Device Creation"
        description = "Sets the Asset Tag of a device when created if it's not already set."

    def run(self, data, commit):
        device = Device.objects.get(pk=data["id"])

        # To generate the correct change log data when editing an existing object,
        # a snapshot of the object must be taken before making any changes to the object.
        if device.pk and hasattr(device, "snapshot"):
            device.snapshot()

        if not device.asset_tag:
            manufacturer_id = device.device_type.manufacturer.id
            serial_number = device.serial

            asset_tag = f"OC{manufacturer_id}{serial_number}"

            device.asset_tag = asset_tag
            device.full_clean()
            device.save()

            self.log_success(f"Asset Tag set to {asset_tag} for Device {device.name}")
        else:
            self.log_info("Asset Tag already set, no action taken.")

[ziggekatten]

As for the field names available on an object, you should look at the API output from /api/dcim/devices/

The rest is picked up from the documentation and standard Python ways of coding.

This with combination with logging and use of nbshell closes any gap to documentation

The logs you find under Operations->Jobs

[MalteMagnussen]

@ziggekatten - I had no idea "nbshell" was a thing. Thanks.

I can see in the shell that using "id" or "pk" is the same thing when doing Device.objects.get

[ziggekatten]

nbshell is my goto for ad-hoc queries. Could not live without it :-) Tab completion and all