netbox2dns

netbox2dns is a tool for publishing DNS records from Netbox data.

Netbox provides a reasonable interface for managing and documenting IP addresses and network devices, but out of the box there's no good way to publish Netbox's data into DNS. This tool is designed to publish A, AAAA, and PTR records from Netbox into Google Cloud DNS. It should be possible to add other DNS providers without too much work, as long as they're able to handle incremental record additions and removals.

Compiling

Check out a copy of the netbox2dns code from GitHub using git clone https://github.com/scottlaird/netbox2dns.git. Then, run go build cmd/netbox2dns/netbox2dns.go, and it should generate a netbox2dns binary. This can be copied to other directories or other systems as needed.

Configuration

Edit netbox2dns.yaml. Here is an example config:

config:
  netbox: 
    host:  "netbox.example.com"
    token: "01234567890abcdef"

  defaults:
    project: "google-cloud-dns-project-name-123456"
    ttl: 300
  
  zones: 
    - name: "internal.example.com"
      zonetype: "clouddns"
      zonename: "internal-example-com"
    - name: "example.com"
      zonetype: "zonefile"
      filename: "/etc/dns/example.com.zone"
    - name: "10.in-addr.arpa"
      zonetype: "clouddns"
      zonename: "reverse-v4-10"
      delete_entries: true
    - name: "0.0.0.0.ip6.arpa"
      zonetype: "clouddns"
      zonename: "reverse-v6-0000"
      delete_entries: true

Each zone needs to specify a name and a zonetype. Currently supported zonetypes are clouddns for Google Cloud DNS and zonefile for text zone files. See config.cue for an authoratative list of parameters per zone.

To talk to Netbox, you'll need to provide your Netbox host, a Netbox API token with (at a minimum) read access to Netbox's IP Address data.

To talk to Google Cloud DNS, you'll need to specify a project ID. This should match the Google Cloud project name that hosts your DNS records on console.cloud.google.com. For now, netbox2dns uses Application Default Credentials. See Google's documentation for how to set these up using the gcloud CLI.

Finally, list your zones. When adding new records, netbox2dns will add records to the longest matching zone name. For the example above, with internal.example.com and example.com, if Netbox has a record for router1.internal.example.com, then it will be added to internal.example.com. Any records that don't fix into a listed zone will be ignored.

By default, netbox2dns will search in /etc/netbox2dns/, /usr/local/etc/netbox2dns/, and the correct directory for its config file. Config files can be in YAML (shown above), JSON, or CUE format. Examples in all 3 formats are available.

Use

Short version: create a configuration file (see previous section), then run netbox2dns diff, followed by netbox2dns push if the diff looks acceptable.

Upon startup, netbox2dns will fetch all IP Address records from Netbox and all A/AAAA/PTR records from the listed zones. netbox2dns ignores other record types, including SOA, NS, and CNAME.

For each active IP address in Netbox that has a DNS name, netbox2dns will try to add both forward and reverse DNS records. Both IPv4 and IPv6 should be handled automatically.

This tool has 2 operating modes, diff and push. diff shows significant differences between DNS zones and Netbox, and push makes changes to DNS.

By default, netbox2dns will only add records from Netbox, and will not remove DNS records for IP addresses that are not in Netbox. In cases where Netbox is authoritative for zone information, you can add the delete_entries: true setting for each zone in the config file. This will make netbox2dns remove unknown A, AAAA, or PTR records from Google Cloud DNS. This makes the most sense for reverse DNS, when Netbox is the source of truth for all IP address assignement.