ci: Activate with darwin-rebuild

.github/workflows/ci.yaml

@@ -29,6 +29,11 @@ jobs:
           printf 'run\tprivate/var/run\n' | sudo tee -a /etc/synthetic.conf
           sudo /System/Library/Filesystems/apfs.fs/Contents/Resources/apfs.util -t || true
 
+      - name: Set up nix-homebrew CI
+        run: |
+          sudo touch /etc/nix-homebrew-ci
+          sudo mv /etc/nix/nix.conf{,.before-nix-darwin}
+
       - name: Migrate existing Homebrew installation (imperative taps)
         run: |
           sudo rm /etc/bashrc

ci/activate-example.sh

@@ -3,6 +3,11 @@ set -euo pipefail
 
 DIR=$(dirname $0)
 
+real_nix="$(type -P nix)"
+nix() {
+  "${real_nix}" --extra-experimental-features "nix-command flakes" "$@"
+}
+
 if [[ "$#" != "1" ]]; then
   >&2 echo "Usage: $0 [example]"
   exit 1
@@ -12,11 +17,12 @@ example="$1"
 system="$(nix eval --raw --impure --expr 'builtins.currentSystem')"
 >&2 echo "System: ${system}"
 
-systemProfile="$(nix build "./${DIR}/..#ci.${system}.${example}.system" -L --no-link --print-out-paths)"
->&2 echo "Built $systemProfile"
+flakeDarwinAttr="${system}.${example}"
 
-sudo rm "/etc/nix/nix.conf"
-sudo "$systemProfile/activate"
-"$systemProfile/activate-user"
+darwinRebuild="$(nix build ".#darwinConfigurations.${flakeDarwinAttr}.config.system.build.darwin-rebuild" -L --no-link --print-out-paths)/bin/darwin-rebuild"
+>&2 echo "Built $darwinRebuild"
+
+set -x
+"$darwinRebuild" switch --flake ".#${flakeDarwinAttr}" -L -v --option extra-experimental-features "nix-command flakes"
 
 # vim: set et ts=2 sw=2:

ci/default.nix

@@ -4,6 +4,13 @@
 
 let
   inherit (pkgs) lib system;
+  checkCIMarker = ''
+    if [[ ! -e /etc/nix-homebrew-ci ]]; then
+      >&2 echo "[!!] This configuration is only intended for nix-homebrew CI"
+      >&2 echo "[!!] Refusing to activate since it will likely brick your machine"
+      exit 1
+    fi
+  '';
   makeProfile = example: nix-darwin.lib.darwinSystem {
     inherit system pkgs;
     modules = [
@@ -15,6 +22,9 @@ let
         nix-homebrew = {
           user = lib.mkForce "runner";
         };
+
+        system.activationScripts.preActivation.text = lib.mkBefore checkCIMarker;
+        system.activationScripts.preUserActivation.text = lib.mkBefore checkCIMarker;
       }
     ];
   };

flake.nix

@@ -34,7 +34,7 @@
       BREW_SRC = brew-src;
     });
 
-    ci = forAllSystems (pkgs: import ./ci (inputs // {
+    darwinConfigurations = forAllSystems (pkgs: import ./ci (inputs // {
       inherit pkgs;
     }));