devcontainer: init

overlay.nix

@@ -9,4 +9,23 @@ in
 
   # docker images must be lower-cased
   docker-nixpkgs = importDir (path: pkgs.callPackage path {}) ./images;
+
+  # used to build nix-env compatible user environments
+  mkUserEnvironment = pkgs.callPackage ./lib/mkUserEnvironment.nix {};
+
+  # gitMinimal still ships with perl and python
+  gitReallyMinimal = (
+    pkgs.git.override {
+      perlSupport = false;
+      pythonSupport = false;
+      withManual = false;
+      withpcre2 = false;
+    }
+  ).overrideAttrs (
+    _: {
+      # installCheck is broken when perl is disabled
+      doInstallCheck = false;
+    }
+  );
+
 }