Update multiple channel support

README.md

@@ -105,6 +105,16 @@ the latest and greatest nix3 flake-enabled command UX.
 
 # What next?
 
+## Multiple nixpkgs channels
+
+`multi-nixpkgs` shows how to setup multiple nixpkgs channels. For example, using the stable channel you can add the unstable version of neovim like:
+
+```
+home.packages = with pkgs; [
+  unstable.neovim
+];
+```
+
 ## Adding more hosts or users
 
 You can organize them by hostname and username on `nixos` and `home-manager`

multi-nixpkgs/flake.lock

@@ -37,10 +37,27 @@
         "type": "github"
       }
     },
+    "nixpkgs-unstable": {
+      "locked": {
+        "lastModified": 1672953546,
+        "narHash": "sha256-oz757DnJ1ITvwyTovuwG3l9cX6j9j6/DH9eH+cXFJmc=",
+        "owner": "nixos",
+        "repo": "nixpkgs",
+        "rev": "a518c77148585023ff56022f09c4b2c418a51ef5",
+        "type": "github"
+      },
+      "original": {
+        "owner": "nixos",
+        "ref": "nixos-unstable",
+        "repo": "nixpkgs",
+        "type": "github"
+      }
+    },
     "root": {
       "inputs": {
         "home-manager": "home-manager",
-        "nixpkgs": "nixpkgs"
+        "nixpkgs": "nixpkgs",
+        "nixpkgs-unstable": "nixpkgs-unstable"
       }
     },
     "utils": {

multi-nixpkgs/flake.nix

@@ -4,6 +4,7 @@
   inputs = {
     # Nixpkgs
     nixpkgs.url = "github:nixos/nixpkgs/nixos-22.11";
+    nixpkgs-unstable.url = "github:nixos/nixpkgs/nixos-unstable";
 
     # Home manager
     home-manager.url = "github:nix-community/home-manager";
@@ -43,7 +44,7 @@
       );
 
       # Your custom packages and modifications, exported as overlays
-      overlays = import ./overlays;
+      overlays = import ./overlays { inherit inputs; };
       # Reusable nixos modules you might want to export
       # These are usually stuff you would upstream into nixpkgs
       nixosModules = import ./modules/nixos;

multi-nixpkgs/home-manager/home.nix

@@ -18,6 +18,7 @@
     # You can add overlays here
     overlays = [
       # Add overlays your own flake exports (from overlays and pkgs dir):
+      outputs.overlays.unstable
       outputs.overlays.modifications
       outputs.overlays.additions
 

multi-nixpkgs/nixos/configuration.nix

@@ -22,6 +22,7 @@
     # You can add overlays here
     overlays = [
       # Add overlays your own flake exports (from overlays and pkgs dir):
+      outputs.overlays.unstable
       outputs.overlays.modifications
       outputs.overlays.additions
 

multi-nixpkgs/overlays/default.nix

@@ -1,5 +1,11 @@
+{ inputs, ... }:
 # This file defines overlays
 {
+  # Sets `unstable` under `pkgs` as the nixpkgs unstable channel
+  unstable = final: _prev: {
+    unstable = inputs.nixpkgs-unstable.legacyPackages.${final.system};
+  };
+
   # This one brings our custom packages from the 'pkgs' directory
   additions = final: _prev: import ../pkgs { pkgs = final; };