flake.nix: build all packages though a single evaluation

Author: charludo

.github/workflows/nix_build.yml

@@ -0,0 +1,37 @@
+name: build and cache all flake outputs
+
+on:
+  pull_request:
+    paths:
+      - "**"
+      - "!.github/**"
+      - ".github/actions/setup_nix.yml"
+      - ".github/workflows/nix_build.yml"
+      - "!dev-docs/**"
+      - "!docs/**"
+      - "!rfc/**"
+      - "!tools/vale/**"
+  workflow_dispatch:
+
+jobs:
+  checks:
+    runs-on: ${{ matrix.runner }}
+    permissions:
+      contents: read
+    strategy:
+      matrix:
+        include:
+          - runner: yet-to-be-set-up-nix-build-host
+            system: x86_64-linux
+    steps:
+      - uses: actions/checkout@93cb6efe18208431cddfb8368fd83d5badbf9bfd # v5.0.1
+        with:
+          persist-credentials: false
+      - uses: ./.github/actions/setup_nix
+        if: (!inputs.self-hosted)
+        with:
+          githubToken: ${{ secrets.GITHUB_TOKEN_IN || secrets.GITHUB_TOKEN }}
+          cachixToken: ${{ secrets.CACHIX_AUTH_TOKEN }}
+      - name: pre-build all flake outputs
+        run: |
+          nix build .#matrix.${{ matrix.system }}

flake.nix

@@ -36,12 +36,13 @@
           overlays = [
             (final: _prev: { fenix = self.inputs.fenix.packages.${final.stdenv.hostPlatform.system}; })
             (import ./overlays/nixpkgs.nix)
-            (import ./overlays/contrast.nix)
+            (import ./overlays/contrast.nix { inherit (self) inputs; })
           ];
           config.allowUnfree = true;
           config.nvidia.acceptLicense = true;
         };
         treefmtEval = treefmt-nix.lib.evalModule pkgs ./treefmt.nix;
+        inherit (pkgs) lib;
       in
 
       {
@@ -57,6 +58,8 @@
             "contrastPkgs"
           ];
         };
+
+        matrix = pkgs.writeText "output-matrix.json" (builtins.toJSON (lib.ci.allOutputs self system));
       }
     );
 

lib/ci.nix

@@ -0,0 +1,22 @@
+{ lib, ... }:
+rec {
+  fromPackageOutputs =
+    flake: system:
+    lib.concatMap (kind: lib.attrValues (lib.attrByPath [ kind system ] { } flake)) [
+      "legacyPackages"
+      "packages"
+      "checks"
+      "devShells"
+      "formatters"
+    ];
+
+  allOutputs =
+    flake: system:
+    lib.filter lib.isDerivation (
+      lib.unique (
+        lib.concatMap (from: from flake system) [
+          fromPackageOutputs
+        ]
+      )
+    );
+}

lib/default.nix

@@ -0,0 +1,12 @@
+{ inputs }:
+
+let
+  mkLib =
+    nixpkgs:
+    nixpkgs.lib.extend (
+      self: _: {
+        ci = import ./ci.nix { lib = self; };
+      }
+    );
+in
+mkLib inputs.nixpkgs

overlays/contrast.nix

@@ -1,8 +1,11 @@
 # Copyright 2024 Edgeless Systems GmbH
 # SPDX-License-Identifier: BUSL-1.1
 
+{ inputs }:
+
 final: _prev:
 
 {
   contrastPkgs = import ../packages { pkgs = final; };
+  lib = import ../lib { inherit inputs; };
 }

packages/contrast-releases.json

@@ -1,9 +1,5 @@
 {
   "contrast": [
-    {
-      "version": "v0.2.0",
-      "hash": "sha256-cGyWvUmL/rbjX3Bu1OPGTZlk5PgVW/O0qdo9KmZPo+U="
-    },
     {
       "version": "v0.3.0",
       "hash": "sha256-8yVZLhwf2bsWIMxSAqXUKDNCjltCSGA6bwrXTi+cJB0="

packages/static.nix

@@ -0,0 +1,16 @@
+# Copyright 2025 Edgeless Systems GmbH
+# SPDX-License-Identifier: BUSL-1.1
+
+{ pkgs }:
+
+let
+  inherit (pkgs.lib) makeScope;
+in
+
+makeScope pkgs.pkgsStatic.newScope (
+  self:
+  pkgs.lib.packagesFromDirectoryRecursive {
+    inherit (self) callPackage newScope;
+    directory = ./by-name;
+  }
+)