metrics: Add metrics with victoriametrics + grafana

configuration/services/postgres.nix

@@ -16,6 +16,12 @@
     # that operation needs to be performed manually on the system as
     # well.
     ensureUsers = [
+      {
+        name = "grafana";
+        ensurePermissions = {
+          "DATABASE grafana" = "ALL PRIVILEGES";
+        };
+      }
       {
         name = "nextcloud";
         ensurePermissions = {
@@ -25,6 +31,7 @@
     ];
 
     ensureDatabases = [
+      "grafana"
       "nextcloud"
     ];
   };