refactor nix flake

.envrc

@@ -1,2 +1,2 @@
-watch_file devshell.toml
 use flake || use nix
+watch_file flake.nix nix/devshell.*

default.nix

@@ -1 +1,2 @@
-(import lib/compat.nix).defaultNix
+# This file allows nix-build to find the flake
+(import nix/flake-compat.nix).defaultNix

flake.lock

@@ -15,13 +15,29 @@
         "type": "github"
       }
     },
+    "flake-compat": {
+      "flake": false,
+      "locked": {
+        "lastModified": 1650374568,
+        "narHash": "sha256-Z+s0J8/r907g149rllvwhb4pKi8Wam5ij0st8PwAh+E=",
+        "owner": "edolstra",
+        "repo": "flake-compat",
+        "rev": "b4a34015c698c7793d592d66adbab377907a2be8",
+        "type": "github"
+      },
+      "original": {
+        "owner": "edolstra",
+        "repo": "flake-compat",
+        "type": "github"
+      }
+    },
     "flake-utils": {
       "locked": {
-        "lastModified": 1623875721,
-        "narHash": "sha256-A8BU7bjS5GirpAUv4QA+QnJ4CceLHkcXdRp4xITDB0s=",
+        "lastModified": 1638122382,
+        "narHash": "sha256-sQzZzAbvKEqN9s0bzWuYmRaA03v40gaJ4+iL1LXjaeI=",
         "owner": "numtide",
         "repo": "flake-utils",
-        "rev": "f7e004a55b120c02ecb6219596820fcd32ca8772",
+        "rev": "74f7e4319258e287b0f9cb95426c9853b282730b",
         "type": "github"
       },
       "original": {
@@ -30,6 +46,25 @@
         "type": "github"
       }
     },
+    "fup": {
+      "inputs": {
+        "flake-utils": "flake-utils"
+      },
+      "locked": {
+        "lastModified": 1638172912,
+        "narHash": "sha256-jxhQGNEsZTdop/Br3JPS+xmBf6t9cIWRzVZFxbT76Rw=",
+        "owner": "gytis-ivaskevicius",
+        "repo": "flake-utils-plus",
+        "rev": "166d6ebd9f0de03afc98060ac92cba9c71cfe550",
+        "type": "github"
+      },
+      "original": {
+        "owner": "gytis-ivaskevicius",
+        "ref": "v1.3.1",
+        "repo": "flake-utils-plus",
+        "type": "github"
+      }
+    },
     "nixpkgs": {
       "locked": {
         "lastModified": 1624553300,
@@ -47,7 +82,8 @@
     "root": {
       "inputs": {
         "devshell": "devshell",
-        "flake-utils": "flake-utils",
+        "flake-compat": "flake-compat",
+        "fup": "fup",
         "nixpkgs": "nixpkgs"
       }
     }

flake.nix

@@ -12,33 +12,45 @@
 # ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
 # OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
 
+# The flake file is the entry point for nix commands
 {
   description = "guest NixOS images with minimal footprint";
 
+  # Inputs are how Nix can use code from outside the flake during evaluation.
   inputs.devshell.url = "github:numtide/devshell";
-  inputs.flake-utils.url = "github:numtide/flake-utils";
+  inputs.fup.url = "github:gytis-ivaskevicius/flake-utils-plus/v1.3.1";
+  inputs.flake-compat.url = "github:edolstra/flake-compat";
+  inputs.flake-compat.flake = false;
 
-  outputs = inputs@{ self, nixpkgs, devshell, flake-utils }:
-    with flake-utils.lib;
-    let
-      overlay = import tool/overlay.nix;
-    in
-    {
-      nixosModules.core = import ./core;
-      nixosModules.declarative = import ./declarative inputs;
-      inherit overlay;
-      defaultTemplate = {
-        description = "Example guest configurations";
-        path = ./template;
+  # Outputs are the public-facing interface to the flake.
+  outputs = inputs@{ self, devshell, fup, nixpkgs, ... }: fup.lib.mkFlake {
+
+    inherit self inputs;
+
+    sharedOverlays = [
+      devshell.overlay
+      self.overlay
+    ];
+
+    overlay = import tool/overlay.nix;
+
+    nixosModules.core = import ./core;
+    nixosModules.declarative = import ./declarative inputs;
+
+    defaultTemplate = {
+      description = "Example guest configurations";
+      path = ./template;
+    };
+
+    outputsBuilder = channels: rec {
+      packages = rec {
+        inherit (channels.nixpkgs) miniguest;
+        default = miniguest;
       };
-    } // eachDefaultSystem (system:
-      let pkgs = import nixpkgs { inherit system; overlays = [ overlay ]; };
-      in
-      {
-        packages.miniguest = pkgs.miniguest;
-        defaultPackage = pkgs.miniguest;
-        defaultApp = mkApp { drv = pkgs.miniguest; };
-        devShell = devshell.legacyPackages.${system}.fromTOML ./devshell.toml;
-        checks = import ./checks inputs system;
-      });
+      defaultPackage = packages.default;
+      defaultApp = fup.lib.mkApp { drv = packages.default; };
+      devShell = channels.nixpkgs.callPackage nix/devshell.nix { };
+      checks = import ./checks inputs channels.nixpkgs.system;
+    };
+  };
 }

nix/devshell.nix

@@ -0,0 +1,3 @@
+{ devshell }:
+
+devshell.fromTOML ./devshell.toml

nix/flake-compat.nix

@@ -1,8 +1,9 @@
 let
-  rev = "99f1c2157fba4bfe6211a321fd0ee43199025dbf";
+  lock = builtins.fromJSON (builtins.readFile ../flake.lock);
+  inherit (lock.nodes.flake-compat.locked) rev narHash;
   flake-compat = fetchTarball {
     url = "https://github.com/edolstra/flake-compat/archive/${rev}.tar.gz";
-    sha256 = "0x2jn3vrawwv9xp15674wjz9pixwjyj3j771izayl962zziivbx2";
+    sha256 = narHash;
   };
 in
 import flake-compat { src = ./..; }

shell.nix

@@ -1 +1,2 @@
-(import lib/compat.nix).shellNix
+# This file allows nix-shell to find the flake
+(import nix/flake-compat.nix).shellNix