juanfont.headscale/docs/ref/dns.md

DNS

Headscale supports most DNS features from Tailscale. DNS releated settings can be configured within dns section of the configuration file.

Setting extra DNS records

Headscale allows to set extra DNS records which are made available via MagicDNS. Extra DNS records can be configured either via static entries in the configuration file or from a JSON file that Headscale continously watches for changes:

• Use the dns.extra_records option in the configuration file for entries that are static and don't change while Headscale is running. Those entries are processed when Headscale is starting up and changes to the configuration require a restart of Headscale.
• For dynamic DNS records that may be added, updated or removed while Headscale is running or DNS records that are generated by scripts the option dns.extra_records_path in the configuration file is useful. Set it to the absolute path of the JSON file containing DNS records and Headscale processes this file as it detects changes.

An example use case is to serve multiple apps on the same host via a reverse proxy like NGINX, in this case a Prometheus monitoring stack. This allows to nicely access the service with "http://grafana.myvpn.example.com" instead of the hostname and port combination "http://hostname-in-magic-dns.myvpn.example.com:3000".

!!! warning "Limitations"

Currently, [only A and AAAA records are processed by Tailscale](https://github.com/tailscale/tailscale/blob/v1.78.3/ipn/ipnlocal/local.go#L4461-L4479).

1. Configure extra DNS records using one of the available configuration options:

   === "Static entries, via dns.extra_records"

   ```yaml title="config.yaml"
   dns:
     ...
     extra_records:
       - name: "grafana.myvpn.example.com"
         type: "A"
         value: "100.64.0.3"
   
       - name: "prometheus.myvpn.example.com"
         type: "A"
         value: "100.64.0.3"
     ...
   ```
   
   Restart your headscale instance.
   

   === "Dynamic entries, via dns.extra_records_path"

   ```json title="extra-records.json"
   [
     {
       "name": "grafana.myvpn.example.com",
       "type": "A",
       "value": "100.64.0.3"
     },
     {
       "name": "prometheus.myvpn.example.com",
       "type": "A",
       "value": "100.64.0.3"
     }
   ]
   ```
   
   Headscale picks up changes to the above JSON file automatically.
   
   !!! tip "Good to know"
   
       * The `dns.extra_records_path` option in the [configuration file](./configuration.md) needs to reference the
         JSON file containing extra DNS records.
       * Be sure to "sort keys" and produce a stable output in case you generate the JSON file with a script.
         Headscale uses a checksum to detect changes to the file and a stable output avoids unnecessary processing.
   

2. Verify that DNS records are properly set using the DNS querying tool of your choice:

   === "Query with dig"

   ```shell
   dig +short grafana.myvpn.example.com
   100.64.0.3
   ```
   

   === "Query with drill"

   ```shell
   drill -Q grafana.myvpn.example.com
   100.64.0.3
   ```
   

3. Optional: Setup the reverse proxy

   The motivating example here was to be able to access internal monitoring services on the same host without specifying a port, depicted as NGINX configuration snippet:

   server {
       listen 80;
       listen [::]:80;
   
       server_name grafana.myvpn.example.com;
   
       location / {
           proxy_pass http://localhost:3000;
           proxy_set_header Host $http_host;
           proxy_set_header X-Real-IP $remote_addr;
           proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
           proxy_set_header X-Forwarded-Proto $scheme;
       }
   
   }