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Safe Mode

Safe mode prevents accidental modification or overwrite of DNS records that are not managed by dns-updater.

When safe mode is enabled, each managed A record has a companion TXT record. dns-updater uses this TXT record to verify ownership before it creates or updates the A record.

Configuration​

Configure safe mode under provider.safemode:

provider:
  safemode:
    enabled: true
    txtOwnerId: dns-updater
    txtPrefix: dns-updater-safemode

Fields​

  • enabled (boolean, default: true): enables or disables safe mode.
  • txtOwnerId (string, default: dns-updater): ownership identifier written to the safemode TXT record.
  • txtPrefix (string, default: dns-updater-safemode): prefix used to build the safemode TXT record name.

Safemode TXT records​

For each managed record, dns-updater creates or requires a companion TXT record.

  • TXT record name: <txt_prefix><record_name>
  • TXT record data: managed-by:dns-updater/<txt_owner_id>

With the default configuration, a record named home uses this companion TXT record:

Name: dns-updater-safemodehome
Data: managed-by:dns-updater/dns-updater

Create and update behavior​

When safe mode is enabled, dns-updater uses the companion TXT record to decide whether it may create or update an A record.

  • For each managed record, dns-updater creates or requires a companion TXT record with the expected ownership data.
  • If the TXT record exists and its data matches the expected ownership value, dns-updater may create or update the A record.
  • If an existing A record has no matching TXT record, or the TXT record data does not match, dns-updater refuses to touch the A record.

This prevents dns-updater from modifying records that it does not own.

Example configuration​

provider:
  name: digitalocean
  config:
    token: your-digitalocean-api-token
  safemode:
    enabled: true
    txtOwnerId: dns-updater
    txtPrefix: dns-updater-safemode

updates:
  - domain: example.com
    zone: example-com
    type: A
    records:
      - home
      - vpn