add flake to ci

.github/workflows/test-flakes.yml

@@ -0,0 +1,29 @@
+name: "Flake test"
+on:
+  pull_request:
+  push:
+    branches:
+      - main
+  schedule:
+    - cron:  '51 2 * * *'
+jobs:
+  tests:
+    strategy:
+      matrix:
+        os: [ ubuntu-latest, macos-latest ]
+    runs-on: ${{ matrix.os }}
+    steps:
+    - uses: actions/checkout@v2
+      with:
+          # Nix Flakes doesn't work on shallow clones
+          fetch-depth: 0
+    - uses: cachix/install-nix-action@v12
+      with:
+        install_url: https://github.com/numtide/nix-flakes-installer/releases/download/nix-2.4pre20210207_fd6eaa1/install
+        extra_nix_config: |
+          experimental-features = nix-command flakes
+          system-features = nixos-test benchmark big-parallel kvm
+    - name: List flake structure
+      run: nix flake show
+    - name: Build
+      run: nix build

.gitignore

@@ -40,3 +40,5 @@ tmp/
 
 # build directory
 /build
+# nix-build
+/result

flake.nix

@@ -6,7 +6,7 @@
 
   outputs = { self, nixpkgs, flake-utils }:
     flake-utils.lib.eachDefaultSystem (system: {
-      packages.hydra-eval-jobs = nixpkgs.legacyPackages.${system}.callPackage ./. {
+      packages.hydra-eval-jobs = nixpkgs.legacyPackages.${system}.callPackage ./hydra.nix {
         srcDir = self;
       };
       defaultPackage = self.packages.${system}.hydra-eval-jobs;

hydra.nix

@@ -6,7 +6,7 @@
 , pkg-config
 , boost
 , nlohmann_json
-, srcDir ? ./.
+, srcDir ? null
 }:
 
 let
@@ -16,7 +16,7 @@ in
 stdenv.mkDerivation rec {
   pname = "hydra-eval-jobs";
   version = "0.0.1";
-  src = filterMesonBuild srcDir;
+  src = if srcDir == null then filterMesonBuild ./. else srcDir;
   buildInputs = [
     nlohmann_json nixFlakes boost
   ];