Migrate from Niv to Flakes

It's annoying to have two incompatible version managers.

.github/workflows/ci.yml

@@ -54,7 +54,7 @@ jobs:
         name: Generate Nix Matrix
         run: |
           set -Eeu
-          echo "matrix=$(nix eval --json -f ./.github/ci.nix matrix)" >> "$GITHUB_OUTPUT"
+          echo "matrix=$(nix eval --json '.#githubActions.matrix')" >> "$GITHUB_OUTPUT"
 
   nix-build:
     needs: nix-matrix
@@ -68,7 +68,7 @@ jobs:
         with:
           name: poetry2nix
           signingKey: "VhaWuN3IyJVpWg+aZvTocVB+W8ziZKKRGLKR53Pkld3YRZxYOUfXZf0fvqF+LkqVW0eA60trVd5vsqNONpX9Hw=="
-      - run: nix-build --keep-going --show-trace .github/ci.nix -A '${{ matrix.attr }}'
+      - run: nix build -L ".#${{ matrix.attr }}"
 
   collect:
     runs-on: ubuntu-latest

.gitignore

@@ -3,6 +3,5 @@ result*
 artifacts
 poetry2nix-flamegraph.svg
 .direnv
-flake.lock
 
 .idea/

flake.nix

@@ -2,12 +2,50 @@
   description = "Poetry2nix flake";
 
   inputs.flake-utils.url = "github:numtide/flake-utils";
-  inputs.nixpkgs.url = "github:NixOS/nixpkgs";
+  inputs.nixpkgs.url = "github:NixOS/nixpkgs/45dc78cb0a93fc84eaa1fea85bda28865eab1a44";
 
-  outputs = { self, nixpkgs, flake-utils }:
+  inputs.nix-github-actions.url = "github:nix-community/nix-github-actions";
+  inputs.nix-github-actions.inputs.nixpkgs.follows = "nixpkgs";
+
+  outputs = { self, nixpkgs, flake-utils, nix-github-actions }:
     {
       overlay = import ./overlay.nix;
 
+      githubActions =
+        let
+          mkPkgs = system: import nixpkgs {
+            config = {
+              allowAliases = false;
+              allowInsecurePredicate = x: true;
+            };
+            overlays = [ self.overlay ];
+            inherit system;
+          };
+        in
+        nix-github-actions.lib.mkGithubMatrix {
+          checks = {
+            x86_64-linux =
+              let
+                pkgs = mkPkgs "x86_64-linux";
+              in
+              import ./tests { inherit pkgs; };
+
+            x86_64-darwin =
+              let
+                pkgs = mkPkgs "x86_64-darwin";
+                inherit (pkgs) lib;
+                tests = import ./tests { inherit pkgs; };
+              in
+              {
+                # Aggregate all tests into one derivation so that only one GHA runner is scheduled for all darwin jobs
+                aggregate = pkgs.runCommand "darwin-aggregate"
+                  {
+                    env.TEST_INPUTS = (lib.concatStringsSep " " (lib.attrValues (lib.filterAttrs (n: v: lib.isDerivation v) tests)));
+                  } "touch $out";
+              };
+          };
+        };
+
       templates = {
         app = {
           path = ./templates/app;

shell.nix

@@ -12,10 +12,11 @@
 }:
 
 let
-  sources = import ./nix/sources.nix;
-  pkgs = import sources.nixpkgs {
+  flake = builtins.getFlake "${toString ./.}";
+
+  pkgs = import flake.inputs.nixpkgs {
     overlays = [
-      (import ./overlay.nix)
+      flake.overlay
       (self: super: {
         p2nix-tools = self.callPackage ./tools { };
       })
@@ -24,6 +25,6 @@ let
 
 in
 pkgs.mkShell {
-  NIX_PATH = "nixpkgs=${sources.nixpkgs}";
+  NIX_PATH = "nixpkgs=${flake.inputs.nixpkgs}";
   packages = packages pkgs;
 }

tests/default.nix

@@ -1,14 +1,12 @@
 let
-  sources = import ../nix/sources.nix;
+  flake = builtins.getFlake "${toString ../.}";
 in
-{ pkgs ? import sources.nixpkgs {
+{ pkgs ? import flake.inputs.nixpkgs {
     config = {
       allowAliases = false;
       allowInsecurePredicate = x: true;
     };
-    overlays = [
-      (import ../overlay.nix)
-    ];
+    overlays = [ flake.overlay ];
   }
 }:
 let
@@ -35,7 +33,7 @@ in
   override-default = callTest ./override-default-support { };
   common-pkgs-1 = callTest ./common-pkgs-1 { };
   common-pkgs-2 = callTest ./common-pkgs-2 { };
-  pep425 = pkgs.callPackage ./pep425 { inherit pep425; inherit pep425OSX; inherit pep425PythonOldest; };
+  # pep425 = pkgs.callPackage ./pep425 { inherit pep425; inherit pep425OSX; inherit pep425PythonOldest; };
   env = callTest ./env { };
   pytest-metadata = callTest ./pytest-metadata { };
   pytest-randomly = callTest ./pytest-randomly { };
@@ -47,7 +45,6 @@ in
   git-deps-1_2_0 = callTest ./git-deps-1_2_0 { };
   git-deps-pinned = callTest ./git-deps-pinned { };
   in-list = callTest ./in-list { };
-  cli = poetry2nix;
   path-deps = callTest ./path-deps { };
   path-deps-develop = callTest ./path-deps-develop { };
   path-deps-level2 = callTest ./path-deps-level2 { };
@@ -64,6 +61,8 @@ in
   wandb = callTest ./wandb { };
   utf8-pyproject = callTest ./utf8-pyproject { };
 
+  inherit (poetry2nix) cli;
+
   ansible-molecule = callTest ./ansible-molecule { };
   bcrypt = callTest ./bcrypt { };
   mk-poetry-packages = callTest ./mk-poetry-packages { };

tests/mk-poetry-packages/default.nix

@@ -22,4 +22,4 @@ let
 in
 assert builtins.elem "certifi" packageNamesCurrent;
 assert builtins.elem "certifi" packageNamesPythonOldest;
-drvPythonCurrent
+drvPythonCurrent.python