Builder is working, kinda

img/builder.nix

@@ -1,21 +1,19 @@
 {
-  bashInteractive,
   buildah,
-  dockerTools,
   git,
-  lib,
+  lib',
   nix,
   nix-output-monitor,
   pkgs,
   podman,
-  writeShellApplication,
+  writeTextFile,
 
   name,
   ...
 }:
 let
   policy = (
-    pkgs.writeTextFile {
+    writeTextFile {
       name = "policy.json";
       text = ''
         {
@@ -25,49 +23,34 @@ let
       destination = "/etc/containers/policy.json";
     }
   );
-  activate = writeShellApplication {
-    name = "activate";
-    runtimeInputs = [ bashInteractive ];
+  nix-conf = writeTextFile {
+    name = "nix.conf";
     text = ''
-      mkdir -p /etc/containers
-      cp ${policy}/etc/containers/policy.json /etc/containers/policy.json;
-      bash "$@"
+      experimental-features = nix-command flakes
     '';
+    destination = "/etc/nix/nix.conf";
   };
 in
-(import "${nix.src.outPath}/docker.nix" {
-  inherit pkgs;
+lib'.mkImage pkgs {
   name = name "builder";
-  tag = "latest";
-
-  bundleNixpkgs = false;
-  Cmd = [
-    (lib.getExe activate)
-  ];
-  extraPkgs = [
-    buildah
-    dockerTools.caCertificates
-    nix-output-monitor
-    podman
-    policy
-  ];
-  flake-registry = (pkgs.formats.json { }).generate "flake-registry.json" ({
-    version = 2;
-    flakes.nixpkgs = {
-      exact = true;
-      from = {
-        id = "nixpkgs";
-        type = "indirect";
-      };
-      to = "${pkgs.path}";
-    };
-  });
-  gitMinimal = git; # We want the full version in this
-  maxLayers = 111;
-  nixConf = {
-    experimental-features = [
-      "nix-command"
-      "flakes"
+  copyToRoot = pkgs.buildEnv {
+    name = "policy";
+    paths = [
+      policy
+      nix-conf
     ];
   };
-})
+  initializeNixDatabase = true;
+  layers = [
+    {
+      deps = [
+        buildah
+        git
+        nix
+        nix-output-monitor
+        podman
+        policy
+      ];
+    }
+  ];
+}