ci: also publish to GitHub Packages

Allow Github users to not have another external dependency.

.github/workflows/nix.yml

@@ -8,6 +8,7 @@ on:
   schedule:
     # Run once per day
     - cron: '0 0 * * *'
+
 jobs:
   build:
     strategy:
@@ -20,7 +21,19 @@ jobs:
         system:
           - x86_64-linux
           - aarch64-linux
+        registry:
+          - name: ghcr.io
+            image_prefix: nix-community/docker-nixpkgs
+            auth: "${{ github.actor }}:${{ secrets.GITHUB_TOKEN }}"
+          - name: ghcr.io
+            image_prefix: nixpkgs
+            auth: "${{ secrets.REGISTRY_AUTH }}"
     runs-on: ubuntu-latest
+
+    permissions:
+      contents: read
+      packages: write
+
     steps:
       - uses: actions/checkout@v4
       - name: Set up QEMU
@@ -33,13 +46,23 @@ jobs:
             extra-platforms = aarch64-linux
       - uses: DeterminateSystems/magic-nix-cache-action@main
 
+      - name: Log in to the Container registry
+        if: "${{ matrix.registry.name == 'ghcr.io' }}"
+        uses: docker/[email protected]
+        with:
+          registry: ${{ matrix.registry.name }}
+          username: ${{ github.actor }}
+          password: ${{ secrets.GITHUB_TOKEN }}
+
       - run: nix-shell --run ./ci.sh
         env:
-          CI_REGISTRY_AUTH: '${{ secrets.REGISTRY_AUTH }}'
+          CI_PROJECT_PATH: '${{ matrix.registry.image_prefix }}'
+          CI_REGISTRY: '${{ matrix.registry.name }}'
+          CI_REGISTRY_AUTH: '${{ matrix.registry.auth }}'
           NIXPKGS_CHANNEL: '${{ matrix.channel }}'
           NIX_SYSTEM_NAME: '${{ matrix.system }}'
 
-  push-manifest:
+  push-manifest-to-docker-hub:
     needs: [build]
     strategy:
       fail-fast: false

ci.sh

@@ -45,8 +45,3 @@ fi
 
 banner "docker push"
 ./push-all "$registry" "$image_prefix" "$image_tag"
-
-if [[ -n "${registry_auth}" && $registry = *docker.io ]]; then
-  banner "docker metadata update"
-  ./dockerhub-metadata "$registry_auth" "$image_prefix"
-fi