Add captive portal detection service

hosts/web-2/configuration.nix

@@ -12,6 +12,7 @@
       ./ip.nix
       ./meow.nix
       ./milchinsel.nix
+      ./ping.nix
       ./prediger.nix
       ./public.nix
       ./radicale.nix

hosts/web-2/ping.nix

@@ -0,0 +1,29 @@
+{ ... }:
+
+{
+  services.nginx.virtualHosts = {
+    "ping.clerie.de" = {
+      enableACME = true;
+      addSSL = true;
+      locations."= /" = {
+        return = ''200 "This domain is used for connectivity checking and captive portal detection\n"'';
+        extraConfig = ''
+          types { } default_type "text/plain; charset=utf-8";
+        '';
+      };
+      locations."/nm-check.txt" = {
+        return = ''200 "NetworkManager is online\n"'';
+        extraConfig = ''
+          types { } default_type "text_plain; charset=utf-8";
+          add_header Cache-Control "max-age=0, must-revalidate";
+        '';
+      };
+      locations."/" = {
+        return = ''404'';
+      };
+      extraConfig = ''
+        access_log off;
+      '';
+    };
+  };
+}