feat: add unstable nixpkgs overlay

flake.lock

@@ -90,11 +90,28 @@
         "type": "github"
       }
     },
+    "nixpkgs-unstable": {
+      "locked": {
+        "lastModified": 1722813957,
+        "narHash": "sha256-IAoYyYnED7P8zrBFMnmp7ydaJfwTnwcnqxUElC1I26Y=",
+        "owner": "nixos",
+        "repo": "nixpkgs",
+        "rev": "cb9a96f23c491c081b38eab96d22fa958043c9fa",
+        "type": "github"
+      },
+      "original": {
+        "owner": "nixos",
+        "ref": "nixos-unstable",
+        "repo": "nixpkgs",
+        "type": "github"
+      }
+    },
     "root": {
       "inputs": {
         "mysecrets": "mysecrets",
         "nix-vscode-extensions": "nix-vscode-extensions",
         "nixpkgs": "nixpkgs",
+        "nixpkgs-unstable": "nixpkgs-unstable",
         "sops-nix": "sops-nix"
       }
     },

flake.nix

@@ -3,6 +3,7 @@
 
   inputs = {
     nixpkgs.url = "github:nixos/nixpkgs/nixos-24.05";
+    nixpkgs-unstable.url = "github:nixos/nixpkgs/nixos-unstable";
 
     # Secrets management
     sops-nix = {
@@ -27,7 +28,13 @@
     };
   };
 
-  outputs = { self, nixpkgs, ... }@inputs: {
+  outputs = { self, nixpkgs, ... }@inputs: let
+    inherit (self) outputs;
+  in {
+  
+    # Custom packages and modifications, exported as overlays
+    overlays = import ./overlays {inherit inputs;};
+
     nixosConfigurations = {
       sesame = nixpkgs.lib.nixosSystem {
         specialArgs = {inherit inputs;};
@@ -37,7 +44,7 @@
         ];
       };
       gwiad = nixpkgs.lib.nixosSystem {
-        specialArgs = {inherit inputs;};
+        specialArgs = {inherit inputs outputs;};
         modules = [
           ./hosts/gwiad/configuration.nix
           # inputs.home-manager.nixosModules.default

hosts/gwiad/configuration.nix

@@ -2,7 +2,7 @@
 # your system. Help is available in the configuration.nix(5) man page, on
 # https://search.nixos.org/options and in the NixOS manual (`nixos-help`).
 
-{ config, lib, pkgs, inputs, ... }:
+{ config, lib, pkgs, inputs, outputs, ... }:
 
 {
   imports =
@@ -43,6 +43,7 @@
     config.allowUnfree = true;
     overlays = [
       inputs.nix-vscode-extensions.overlays.default
+      outputs.overlays.unstable-packages
     ];
   };
 

overlays/default.nix

@@ -0,0 +1,11 @@
+# This file defines overlays
+{inputs, ...}: {
+  # When applied, the unstable nixpkgs set (declared in the flake inputs) will
+  # be accessible through 'pkgs.unstable'
+  unstable-packages = final: _prev: {
+    unstable = import inputs.nixpkgs-unstable {
+      system = final.system;
+      config.allowUnfree = true;
+    };
+  };
+}