Now have a builder image that can actually nix build

img/builder.nix

@@ -1,5 +1,6 @@
 {
   buildah,
+  fakeNss,
   git,
   lib',
   nix,
@@ -35,6 +36,14 @@ lib'.mkImage {
   name = name "builder";
   contents = lib'.basePackages ++ [
     buildah
+    (fakeNss.override {
+      extraPasswdLines = [
+        "nixbld:x:1001:1001:Build user:/home/nixbld:/noshell"
+      ];
+      extraGroupLines = [
+        "nixbld:!:1001:nixbld"
+      ];
+    })
     git
     nix
     nix-conf