hosts/monitoring-3: Alert on broken IPv4 to IPv6 proxy

hosts/monitoring-3/rules.yml

@@ -87,3 +87,11 @@ groups:
     annotations:
       summary: "GPG {{ $labels.fingerprint }} is expiring soon"
       description: "GPG with fingerprint {{ $labels.fingerprint }} is expiring in less then six weeks"
+  - alert: NadjaTopIPv4ProxyBroken
+    expr: probe_success{job="blackbox_local_http6", target="blog.nadja.top"} != on (target) probe_success{job="blackbox_local_http4", target="blog.nadja.top"}
+    for: 5m
+    labels:
+      severity: critical
+    annotations:
+      summary: "blog.nadja.top unreachable via IPv4"
+      description: "blog.nadja.top unreachable IPv4, but reachable via IPv6"

modules/nginx-port-forward/default.nix

@@ -9,7 +9,7 @@ let
 
   mkServerBlock = isUDP: port: forward: ''
     server {
-      resolver 127.0.0.53 ipv4=off;
+      resolver 127.0.0.53 ipv4=off valid=30s;
 
       listen ${port}${optionalString isUDP " udp"}${optionalString (forward.certName != null) " ssl"};
       listen [::]:${port}${optionalString isUDP " udp"}${optionalString (forward.certName != null) " ssl"};