refactor: derive host name solely from host directory name

utils/default.nix

@@ -1,12 +1,8 @@
 { lib }:
 
 let
-  hosts = import ./hosts.nix;
+  fs = import ./fs.nix { inherit lib; };
+  hosts = import ./hosts.nix { inherit lib; };
   secrets = import ./secrets.nix { inherit lib; };
 in
-{
-  dirNames =
-    path: builtins.attrNames (lib.filterAttrs (_: type: type == "directory") (builtins.readDir path));
-}
-// hosts
-// secrets
+fs // hosts // secrets

utils/fs.nix

@@ -0,0 +1,6 @@
+{ lib }:
+
+{
+  dirNames =
+    path: builtins.attrNames (lib.filterAttrs (_: t: t == "directory") (builtins.readDir path));
+}

utils/hosts.nix

@@ -1,3 +1,8 @@
+{ lib }:
+
+let
+  fs = import ./fs.nix { inherit lib; };
+in
 {
   hostMeta =
     hostDir:
@@ -5,4 +10,10 @@
       import (hostDir + "/meta.nix")
     else
       throw "meta.nix required in ${hostDir}";
+
+  adminHosts =
+    hostsPath:
+    builtins.filter (host: ((import (hostsPath + "/${host}/host.nix")).host.admin or false)) (
+      fs.dirNames hostsPath
+    );
 }