netbox-autodns

Receive Netbox webhooks and create, update and delete forward and/or reverse DNS records using the go-powerdns module.

Requirements

• A working Netbox and PowerDNS setup
• PowerDNS must have the API enabled with an API key

This has been tested with Netbox v3.5.2 and newer.

Configuration

These environment variables are available to configure the application, showing the default values:

LISTEN_ADDRESS=":8080"                   # IP and port to bind to
PDNS_API_HOST="http://dns.example.com"   # The PowerDNS API URL (required)
PDNS_API_KEY="ChangeMe"                  # PowerDNS API key (required)
DOMAIN="example.com"                     # Domain to be used for forward records (required, even if not used)
SECRET=""                                # Optional secret to verify the HMAC signature of the webhook request
SKIP_FORWARD_RECORDS=""                  # If set to anything then disable the creation of forward records
SKIP_REVERSE_RECORDS=""                  # If set to anything then disable the creation of reverse records

Netbox configuration

Two webhooks are used, one for creating and updating the records and one for deleting. The create/update webhook has some conditionals set to only send requests matching certain criteria, while the delete webhook will send a request for any delete operation.

Create/update

Something like this should work:

• Content types: IPAM > IP Address
• Events: Creations + Updated
• HTTP method: POST
• HTTP content type: application/json
• Conditions:

{
	"and": [
		{
			"attr": "status.value",
			"value": "active"
		},
		{
			"attr": "vrf",
			"value": null
		},
		{
			"attr": "dns_name",
			"value": "",
			"negate": true
		}
	]
}

The conditions will ensure a request only is sent if the status of the IP address is active, the VRF is not set (implying the global VRF), and the DNS name field is non-empty.

If you're using a Netbox version newer than 3.5.3 you can also add a dependency on the tag "auto-dns" by adding this:

{
	"op": "contains",
	"attr": "tags.name",
	"value": "auto-dns"
}

Now whenever an IP address is created, updated or deleted this should be reflected in the DNS zones.

Delete

• Content types: IPAM > IP Address
• Events: Deletions
• HTTP method: POST
• HTTP content type: application/json

Security concerns

It's possible to modify and/or delete already existing records, also those that's created outside of Netbox.

Known issues

• If certain steps are taken the old DNS records are not removed. The steps involved is as follow:
  • Create an IP address specifying the DNS name
  • Edit the IP address and remove the DNS name
  • Edit the IP address again and set the DNS name
• All zones are presumed to be /24 for IPv4, and /32 for IPv6