Merge pull request #76 from jD91mZM2/flake

Flake support

.envrc

@@ -0,0 +1 @@
+eval "$(lorri direnv)"

default.nix

@@ -1,14 +1,3 @@
-{ pkgs ? import <nixpkgs> {} }:
-
-with pkgs;
-stdenv.mkDerivation {
-  name = "nixos-generators";
-  src = lib.cleanSource ./.;
-  meta.description = "Collection of image builders";
-  nativeBuildInputs = [ makeWrapper ];
-  installFlags = [ "PREFIX=$(out)" ];
-  postFixup = ''
-    wrapProgram $out/bin/nixos-generate \
-      --prefix PATH : ${lib.makeBinPath [ jq coreutils findutils nix ] }
-  '';
-}
+(import (builtins.fetchTarball https://github.com/edolstra/flake-compat/archive/master.tar.gz) {
+  src = ./.;
+}).defaultNix.default

flake.lock

@@ -0,0 +1,25 @@
+{
+  "nodes": {
+    "nixpkgs": {
+      "locked": {
+        "lastModified": 1603153815,
+        "narHash": "sha256-uCav0CJ0Zm0vbqJiS9NUYD4XZg4Ww9bbsFzcDUzh2+U=",
+        "owner": "NixOS",
+        "repo": "nixpkgs",
+        "rev": "007126eef72271480cb7670e19e501a1ad2c1ff2",
+        "type": "github"
+      },
+      "original": {
+        "id": "nixpkgs",
+        "type": "indirect"
+      }
+    },
+    "root": {
+      "inputs": {
+        "nixpkgs": "nixpkgs"
+      }
+    }
+  },
+  "root": "root",
+  "version": 7
+}

flake.nix

@@ -0,0 +1,49 @@
+{
+  description = "nixos-generators - one config, multiple formats";
+
+  outputs = { self, nixpkgs }: let
+    forAllSystems = nixpkgs.lib.genAttrs [ "x86_64-linux" "x86_64-darwin" "i686-linux" "aarch64-linux" ];
+  in {
+    # Packages
+    packages = forAllSystems (system: let
+      pkgs = nixpkgs.legacyPackages."${system}";
+    in {
+      nixos-generators = pkgs.stdenv.mkDerivation {
+        name = "nixos-generators";
+        src = ./.;
+        meta.description = "Collection of image builders";
+        nativeBuildInputs = with pkgs; [ makeWrapper ];
+        installFlags = [ "PREFIX=$(out)" ];
+        postFixup = ''
+          wrapProgram $out/bin/nixos-generate \
+            --prefix PATH : ${pkgs.lib.makeBinPath (with pkgs; [ jq coreutils findutils ])}
+        '';
+      };
+
+      # Currently, you need to mark your configurations with makeOverridable in
+      # order to use nixos-generate on them.
+      nixosConfigurations.example = nixpkgs.lib.makeOverridable nixpkgs.lib.nixosSystem {
+        inherit system;
+        modules = [
+          ./configuration.nix
+        ];
+      };
+    });
+    defaultPackage = forAllSystems (system: self.packages."${system}".nixos-generators);
+
+    devShell = forAllSystems (system: let
+      pkgs = nixpkgs.legacyPackages."${system}";
+    in pkgs.mkShell {
+      buildInputs = with pkgs; [ jq coreutils findutils ];
+    });
+
+    # Make it runnable with `nix app`
+    apps = forAllSystems (system: {
+      nixos-generate = {
+        type    = "app";
+        program = "${self.packages."${system}".nixos-generators}/bin/nixos-generate";
+      };
+    });
+    defaultApp = forAllSystems (system: self.apps."${system}".nixos-generate);
+  };
+}

nixos-generate

@@ -1,5 +1,4 @@
-#!/usr/bin/env nix-shell
-#! nix-shell -i bash -p jq
+#!/usr/bin/env bash
 set -euo pipefail
 
 ## Configuration
@@ -8,6 +7,8 @@ readonly libexec_dir="${0%/*}"
 readonly format_dir=$libexec_dir/formats
 
 configuration=${NIXOS_CONFIG:-$libexec_dir/configuration.nix}
+flake_uri=
+flake_attr=
 format_path=
 target_system=
 cores=
@@ -29,6 +30,8 @@ Options:
 * --help: shows this help
 * -c, --configuration PATH:
     select the nixos configuration to build. Default: $configuration
+* --flake URI:
+    selects the nixos configuration to build, using flake uri like "~/dotfiles#my-config"
 * -f, --format NAME: select one of the pre-determined formats
 * --format-path PATH: pass a custom format
 * --list: list the available built-in formats
@@ -61,6 +64,16 @@ while [[ $# -gt 0 ]]; do
       configuration=$2
       shift
       ;;
+    --flake)
+      # Note: The reason I'm using awk over cut is because cutting with an
+      # out-of-bounds field will return the last in-bound field instead of empty
+      # string.
+      flake="$(echo "$2" | awk -F'#' '{ print $1; }')"
+
+      flake_uri="$(nix flake info --json -- "$flake" | jq -r .url)"
+      flake_attr="$(echo "$2" | awk -F'#' '{ print $2; }')"
+      shift
+      ;;
     --cores)
       cores=$2
       shift
@@ -123,10 +136,18 @@ if [[ ! -f $format_path ]]; then
   abort "format file not found: $format_path"
 fi
 
-nix_args+=(
-  -I "nixos-config=$configuration"
-  -I "format-config=$format_path"
-)
+nix_args+=(--argstr formatConfig "$(realpath "$format_path")")
+
+if [[ -z "$flake_uri" ]]; then
+  nix_args+=(
+    -I "nixos-config=$configuration"
+  )
+else
+  nix_args+=(
+    --argstr flakeUri "$flake_uri"
+    --argstr flakeAttr "${flake_attr:-"$(hostname)"}"
+  )
+fi
 
 if [[ -n $target_system ]]; then
   nix_args+=(--argstr system "$target_system")

nixos-generate.nix

@@ -1,7 +1,11 @@
 { nixpkgs ? <nixpkgs>
 , configuration ? <nixos-config>
-, format-config ? <format-config>
 , system ? builtins.currentSystem
+
+, formatConfig
+
+, flakeUri ? null
+, flakeAttr ? null
 }:
 let
   module = { lib, ... }: {
@@ -17,12 +21,21 @@ let
       };
     };
   };
+
+  # Will only get evaluated when used, so no worries
+  flake = builtins.getFlake flakeUri;
+  flakeSystem = flake.outputs.packages."${system}".nixosConfigurations."${flakeAttr}" or flake.outputs.nixosConfigurations."${flakeAttr}";
 in
-import "${toString nixpkgs}/nixos/lib/eval-config.nix" {
-  inherit system;
-  modules = [
-    module
-    format-config
-    configuration
-  ];
-}
+  if flakeUri != null then
+    flakeSystem.override (attrs: {
+      modules = attrs.modules ++ [ module formatConfig ];
+    })
+  else
+    import "${toString nixpkgs}/nixos/lib/eval-config.nix" {
+      inherit system;
+      modules = [
+        module
+        formatConfig
+        configuration
+      ];
+    }

shell.nix

@@ -0,0 +1,3 @@
+(import (builtins.fetchTarball https://github.com/edolstra/flake-compat/archive/master.tar.gz) {
+  src = ./.;
+}).shellNix.default