arbret: our side of running it on vipy

prd-arbret was folded into vipy. arbret itself (app, worker, Postgres, timers,
its backup dump) is deployed by its owner's own repo; this repo owns the
shared host's side of it. arbret_handoff.md documents the split, the Gatus
push API and the backup contract.

- services/arbret: arbret.com -> localhost:3100, www redirects to the apex,
  port 4117 allowed on tailscale0 only, /opt/backups/arbret pre-created to
  the contract so the pull job is green before the first dump.
- headscale ACL: framie may reach prd-vipy:4117.
- vipy: arbret-server, arbret-worker and postgresql in the unit checks.
- 402: DNS and HTTP checks for arbret.com, www, and /api/health with
  [BODY].status == ok. Entries may now name an fqdn outside root_domain and
  add conditions.
- 403: probes arbret-analytics (hourly, 130m window) and arbret-beancount
  (daily, 26h), pushing with the dedicated arbret token.
- backups: pull from backup-pull@prd-vipy:/opt/backups/arbret/, and a
  backup-dump_arbret endpoint.

Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>

ansible/infra/402_public_monitoring.yml

@@ -35,6 +35,11 @@
       - {sub: "{{ subdomains.monero_explorer }}",    host: vipy}
       - {sub: "{{ subdomains.music }}",              host: vipy}
       - {sub: "{{ subdomains.jar_lid_archive_staging }}", host: vipy}
+      # Not under root_domain, so named in full. arbret.com's zone is NOT in
+      # Porkbun (mynymdns) - this is the check that would have caught it still
+      # pointing at prd-arbret's recycled IP after the 2026-10-17 rebuild.
+      - {fqdn: arbret.com,     host: vipy}
+      - {fqdn: www.arbret.com, host: vipy}
 
     # A public resolver on purpose: this must test what the internet sees, not
     # what a local cache or the tailnet's MagicDNS happens to answer.
@@ -68,6 +73,13 @@
       # tailnet hop, gunicorn, and the database and bucket behind it (503 if
       # either is down). "/" would only prove the login redirect works.
       - {name: jars-staging, sub: "{{ subdomains.jar_lid_archive_staging }}", path: "/health/", status: 200}
+      # arbret (runs on vipy since 2026-10-17; deployed by the arbret repo, not
+      # this one). /api/health answers 200 + "status":"ok" when healthy and 503
+      # "degraded" otherwise, DB down included - per the arbret owner. The body
+      # condition guards against a 200 that is not actually healthy.
+      - {name: arbret,        fqdn: arbret.com, path: "/",           status: 200}
+      - {name: arbret-health, fqdn: arbret.com, path: "/api/health", status: 200,
+         conditions: ['[BODY].status == ok']}
 
     # Ports published from the edge host by socket_proxy.
     public_tcp:
@@ -107,11 +119,11 @@
     - name: Build the DNS endpoints
       ansible.builtin.set_fact:
         dns_endpoints: "{{ dns_endpoints | default([]) + [{
-          'name': item.sub ~ '.' ~ root_domain,
+          'name': (item.fqdn if item.fqdn is defined else item.sub ~ '.' ~ root_domain),
           'group': 'dns',
           'url': dns_resolver,
           'interval': item.interval | default('6h'),
-          'dns': {'query-type': 'A', 'query-name': item.sub ~ '.' ~ root_domain},
+          'dns': {'query-type': 'A', 'query-name': (item.fqdn if item.fqdn is defined else item.sub ~ '.' ~ root_domain)},
           'conditions': ['[DNS_RCODE] == NOERROR',
                          '[BODY] == ' ~ hostvars[item.host].ansible_host],
           'alerts': [{'type': 'signal', 'failure-threshold': 1,
@@ -128,10 +140,11 @@
         http_endpoints: "{{ http_endpoints | default([]) + [{
           'name': item.name,
           'group': 'public',
-          'url': 'https://' ~ item.sub ~ '.' ~ root_domain ~ item.path,
+          'url': 'https://' ~ (item.fqdn if item.fqdn is defined else item.sub ~ '.' ~ root_domain) ~ item.path,
           'interval': item.interval | default('5m'),
           'conditions': ['[STATUS] == ' ~ item.status,
-                         '[CERTIFICATE_EXPIRATION] > 168h'],
+                         '[CERTIFICATE_EXPIRATION] > 168h']
+                        + item.conditions | default([]),
           'alerts': [{'type': 'signal', 'failure-threshold': item.threshold | default(3),
                       'success-threshold': 2, 'send-on-resolved': true,
                       'minimum-reminder-interval': '6h'}]}] }}"