From 46e1d2a1552d4aaad676faf49cb0582515d62c86 Mon Sep 17 00:00:00 2001
From: Kjetil Orbekk <kj@orbekk.com>
Date: Sun, 7 Mar 2021 14:17:48 -0500
Subject: Properly wrap up unstable in flake config

---
 flake.nix | 33 +++++++++++++++++++++++++++++----
 1 file changed, 29 insertions(+), 4 deletions(-)

diff --git a/flake.nix b/flake.nix
index 2de484b..d94478d 100644
--- a/flake.nix
+++ b/flake.nix
@@ -11,6 +11,26 @@
   inputs.nix.inputs.nixpkgs.follows = "nixpkgs";
 
   outputs = { self, nixpkgs, nixpkgs-unstable, nix, nixos-hardware, home-manager }:
+    let
+      system = "x86_64-linux";
+
+      pkgs-module = {config, ...}:
+        let
+          cfg = config.nixpkgs;
+
+          unstable-overlay = final: prev: {
+            unstable = import nixpkgs-unstable {
+              inherit (cfg) config localSystem crossSystem;
+            };
+          };
+        in {
+        nixpkgs.pkgs = import nixpkgs {
+          inherit (cfg) config localSystem crossSystem;
+          overlays = cfg.overlays ++ [ unstable-overlay ];
+        };
+      };
+
+    in
     {
       nixosConfigurations = let
         mkConfig = { hostName
@@ -18,23 +38,28 @@
                    , system ? "x86_64-linux" }: {
           name = hostName;
           value = nixpkgs.lib.nixosSystem {
-            system = "x86_64-linux";
+            inherit system;
+
             modules =
               [
+                pkgs-module
                 module
                 nixpkgs.nixosModules.notDetected
                 ({config, pkgs, ...}: {
                   # Let 'nixos-version --json' know about the Git revision
                   # of this flake.
                   system.configurationRevision =
-                    if self ? rev then self.rev else "DIRTY";
+                    let
+                      lastModified = final.substring 0 8 (self.lastModifiedDate or self.lastModified or "19700101");
+                    in
+                    "${lastModified}.${self.shortRev or "dirty"}";
 
                   nixpkgs.overlays = [
                     # Add unstable packages.
                     (final: prev: {
                       my-extras = {
-                        inherit nixpkgs;
-                        inherit nixpkgs-unstable;
+                        # inherit nixpkgs;
+                        # inherit nixpkgs-unstable;
                         inherit nixos-hardware;
                       };
                     })
-- 
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