Add a config for the disc recovery machine.

nix/configuration/roles/git/default.nix

@@ -54,23 +54,17 @@ in
         nixpkgs.overlays = [
           (final: prev: {
             my_git = (
-              pkgs.buildEnv {
-                name = prev.git.name;
-                version = prev.git.version;
+              pkgs.symlinkJoin {
+                name = final.git.name;
+                version = final.git.version;
                 paths =
-                  (builtins.map (git_wrapped prev.git) [
+                  (builtins.map (git_wrapped final.git) [
                     "git"
                   ])
                   ++ [
-                    prev.git
+                    final.git
                   ];
-                extraOutputsToInstall = [
-                  "man"
-                  "doc"
-                  "info"
-                ];
                 nativeBuildInputs = [ final.makeWrapper ];
-                ignoreCollisions = true;
               }
             );
           })
@@ -79,7 +73,7 @@ in
       (lib.mkIf (!config.me.graphical) {
         nixpkgs.overlays = [
           (final: prev: {
-            my_git = prev.git;
+            my_git = final.git;
           })
         ];
       })

nix/configuration/roles/recovery/default.nix

@@ -0,0 +1,34 @@
+{
+  config,
+  lib,
+  pkgs,
+  ...
+}:
+
+{
+  imports = [ ];
+
+  options.me = {
+    recovery.enable = lib.mkOption {
+      type = lib.types.bool;
+      default = false;
+      example = true;
+      description = "Whether we want to install recovery.";
+    };
+  };
+
+  config = lib.mkIf config.me.recovery.enable (
+    lib.mkMerge [
+      {
+        environment.systemPackages = with pkgs; [
+          ddrescue
+        ];
+      }
+      (lib.mkIf config.me.graphical {
+        environment.systemPackages = with pkgs; [
+          ddrescueview
+        ];
+      })
+    ]
+  );
+}