release: init action to create release with buildkite artifacts (#150)

* buildkite: also build x86_64-darwin

* release: init action to create release with buildkite artifacts

.buildkite/pipeline.yml

@@ -1,4 +1,13 @@
 steps:
+  - label: nix-installer-x86_64-darwin
+    agents:
+      mac: 1
+      system: x86_64-darwin
+      nix: 1
+    command:
+      - nix --extra-experimental-features "nix-command flakes" build .#packages.x86_64-darwin.nix-installer -L
+      - cp result/bin/nix-installer ./nix-installer-x86_64-darwin
+      - buildkite-agent artifact upload nix-installer-x86_64-darwin
   - label: nix-installer-aarch64-darwin
     agents:
       mac: 1

.github/workflows/release.yml

@@ -0,0 +1,28 @@
+name: Release
+
+permissions:
+  contents: write
+
+on:
+  push:
+    tags:
+      - "v*.*.*"
+
+jobs:
+  release:
+    runs-on: ubuntu-latest
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v3
+      - name: Download Buildkite Artifacts
+        uses: EnricoMi/download-buildkite-artifact-action@v1.14
+        with:
+          buildkite_token: ${{ secrets.BUILDKITE_TOKEN }}
+          output_path: artifacts
+      - name: Publish Release
+        uses: softprops/action-gh-release@v1
+        with:
+          fail_on_unmatched_files: true
+          files: |
+            artifacts/**
+            nix-installer.sh