add a route for /_synapse/admin, point mjolnir at it

This is whitelisted to just bicep

As a side-effect it's also much easier to use synapse-admin now

hosts/bicep/services/matrix/mjolnir.nix

@@ -11,7 +11,7 @@
   services.mjolnir = {
     enable = true;
     pantalaimon.enable = false;
-    homeserverUrl = "http://127.0.0.1:8008";
+    homeserverUrl = "https://matrix.pvv.ntnu.no";
     accessTokenFile = config.sops.secrets."matrix/mjolnir/access_token".path;
     managementRoom = "!gsdeCoWjvYRBrzuiRq:pvv.ntnu.no";
     protectedRooms = map (a: "https://matrix.to/#/${a}") [

hosts/bicep/services/matrix/synapse.nix

@@ -157,6 +157,18 @@ in {
       '';
     };
   }
+  {
+    locations."/_synapse/admin" = {
+      proxyPass = "http://$synapse_backend";
+      extraConfig = ''
+        allow 127.0.0.1;
+        allow ::1;
+        allow ${values.hosts.bicep.ipv4};
+        allow ${values.hosts.bicep.ipv6};
+        deny all;
+      '';
+    };
+  }
   {
     locations = let
       connectionInfo = w: matrix-lib.workerConnectionResource "metrics" w;