Add a nix-flake-repl script.

nix/configuration/configuration.nix

@@ -54,6 +54,7 @@
     ./roles/minimal_base
     ./roles/network
     ./roles/nix_index
+    ./roles/nix_repl
     ./roles/nix_worker
     ./roles/nixdev
     ./roles/nvme

nix/configuration/flake.nix

@@ -1,6 +1,3 @@
-# Get a repl for this flake
-#   nix repl --expr "builtins.getFlake \"$PWD\""
-
 # TODO maybe use `nix eval --raw .#odo.iso.outPath`
 
 #
@@ -93,29 +90,6 @@
                 ];
               };
             }
-            (
-              {
-                config,
-                lib,
-                pkgs,
-                ...
-              }:
-              let
-                nix-self-repl = pkgs.writeShellScriptBin "nix-self-repl" ''
-                  source /etc/set-environment
-                  nix repl --expr 'builtins.getFlake "${self}"'
-                '';
-                # If we wanted the current version of a flake then we'd just launch
-                #   nix repl
-                # and then run:
-                #   :lf /path/to/flake
-              in
-              {
-                config = {
-                  environment.systemPackages = lib.mkIf config.nix.enable [ nix-self-repl ];
-                };
-              }
-            )
           ];
         }
       ) nodes;
@@ -127,29 +101,6 @@
           };
           modules = [
             ./formats/installer.nix
-            (
-              {
-                config,
-                lib,
-                pkgs,
-                ...
-              }:
-              let
-                nix-self-repl = pkgs.writeShellScriptBin "nix-self-repl" ''
-                  source /etc/set-environment
-                  nix repl --expr 'builtins.getFlake "${self}"'
-                '';
-                # If we wanted the current version of a flake then we'd just launch
-                #   nix repl
-                # and then run:
-                #   :lf /path/to/flake
-              in
-              {
-                config = {
-                  environment.systemPackages = lib.mkIf config.nix.enable [ nix-self-repl ];
-                };
-              }
-            )
             ({ nixpkgs.hostPlatform.system = nodeConfig.system; })
           ];
         };

nix/configuration/hosts/odo/default.nix

@@ -114,6 +114,7 @@
     me.memtest.enable = true;
     me.network.enable = true;
     me.nix_index.enable = true;
+    me.nix_repl.enable = true;
     me.nixdev.enable = true;
     me.nvme.enable = true;
     me.openpgp_card_tools.enable = true;

nix/configuration/hosts/odowork/default.nix

@@ -115,6 +115,7 @@
     me.memtest.enable = true;
     me.network.enable = true;
     me.nix_index.enable = true;
+    me.nix_repl.enable = true;
     me.nixdev.enable = true;
     me.nvme.enable = true;
     me.openpgp_card_tools.enable = true;

nix/configuration/hosts/quark/default.nix

@@ -108,6 +108,7 @@
     me.memtest.enable = true;
     me.network.enable = true;
     me.nix_index.enable = true;
+    me.nix_repl.enable = true;
     me.nix_worker.enable = true;
     me.nixdev.enable = true;
     me.nvme.enable = true;

nix/configuration/roles/nix_repl/default.nix

@@ -0,0 +1,38 @@
+{
+  config,
+  lib,
+  pkgs,
+  self,
+  ...
+}:
+
+let
+  nix-flake-repl = pkgs.writeShellScriptBin "nix-flake-repl" ''
+    source /etc/set-environment
+    target="''${1:-$(pwd)}"
+    nix repl --expr "builtins.getFlake \"''$target\""
+  '';
+  nix-self-repl = pkgs.writeShellScriptBin "nix-self-repl" ''
+    source /etc/set-environment
+    nix repl --expr 'builtins.getFlake "${self}"'
+  '';
+in
+{
+  imports = [ ];
+
+  options.me = {
+    nix_repl.enable = lib.mkOption {
+      type = lib.types.bool;
+      default = false;
+      example = true;
+      description = "Whether we want to install nix_repl.";
+    };
+  };
+
+  config = lib.mkIf config.me.nix_repl.enable {
+    environment.systemPackages = [
+      nix-flake-repl
+      nix-self-repl
+    ];
+  };
+}