Publish placeholder DNS on registration

karldns/services/ddns.py

@@ -20,6 +20,7 @@ from ..settings import DdnsSettings
 from ..store import DdnsStore
 
 LOGGER = logging.getLogger(__name__)
+INITIAL_PLACEHOLDER_IPV4 = "192.0.2.1"
 
 
 @dataclass(slots=True)
@@ -79,14 +80,20 @@ class DdnsService:
         source_fallback = source_ip if _is_global_ip(source_ip) else ""
         supplied_ip = any(value and value.strip() for value in (myip, ipaddr, myipv6, ip6addr))
         if not supplied_ip and not source_fallback:
-            return False
-        ipv4, ipv6, update_ipv4, update_ipv6 = parse_update_ips(
-            source_fallback,
-            myip,
-            ipaddr,
-            myipv6,
-            ip6addr,
-        )
+            ipv4 = INITIAL_PLACEHOLDER_IPV4
+            ipv6 = None
+            update_ipv4 = True
+            update_ipv6 = False
+            detail = "initial placeholder dns registered"
+        else:
+            ipv4, ipv6, update_ipv4, update_ipv6 = parse_update_ips(
+                source_fallback,
+                myip,
+                ipaddr,
+                myipv6,
+                ip6addr,
+            )
+            detail = "initial dns registered"
         lock = self._lock_for(hostname)
         with lock:
             planned = self.store.preview_update(hostname, ipv4, ipv6, update_ipv4=update_ipv4, update_ipv6=update_ipv6)
@@ -114,7 +121,7 @@ class DdnsService:
                     self.store.log_update_event(hostname, ipv4, ipv6, DNS_FAILED, f"{type(exc).__name__}: {exc}", source_ip)
                     raise
             result = self.store.commit_update_result(planned)
-            self.store.log_update_event(hostname, result.ipv4, result.ipv6, UPDATED, "initial dns registered", source_ip)
+            self.store.log_update_event(hostname, result.ipv4, result.ipv6, UPDATED, detail, source_ip)
         return True
 
     def apply_update(

karldns/web/templates_public.py

@@ -183,7 +183,7 @@ def _render_api_docs_page(settings: DdnsSettings, request_ip: str | None = None)
                 <h2>Endpoints</h2>
                 <ol class="simple-steps text-start">
                   <li><strong>POST /api/v1/hostnames.</strong> Create a pending hostname and private setup values. The response includes <code>registration_url</code>.</li>
-                  <li><strong>GET or POST /api/v1/router/register/&lt;karl_secret&gt;.</strong> Register the hostname after secrets are saved. Publishes an initial DNS record when a public request IP or explicit <code>myip</code>/<code>myipv6</code> value is available; otherwise the first router update publishes it.</li>
+                  <li><strong>GET or POST /api/v1/router/register/&lt;karl_secret&gt;.</strong> Register the hostname after secrets are saved. Publishes an initial DNS record from a public request IP or explicit <code>myip</code>/<code>myipv6</code> value. If no public IP is visible, publishes a temporary <code>192.0.2.1</code> A record until the first router update.</li>
                   <li><strong>GET or POST /api/v1/router/update/&lt;karl_secret&gt;.</strong> Router-friendly update endpoint. Supports <code>myip</code>, <code>ipaddr</code>, <code>myipv6</code>, and <code>ip6addr</code>.</li>
                   <li><strong>GET /api/v1/hostnames/&lt;karl_secret&gt;.</strong> Read hostname status and recent history.</li>
                   <li><strong>POST /api/v1/hostnames/&lt;karl_secret&gt;/rotate-update-url.</strong> Replace the private router update URL.</li>