perf: use native ARM runners for publish instead of QEMU

Split publish into build + merge jobs:
- build: matrix of PG version × runner (ubuntu-latest, ubuntu-24.04-arm),
  each pushes a single-platform image by digest
- merge: downloads digests per PG version and creates multi-arch manifests

Eliminates QEMU emulation overhead for ARM builds.

Author: naorpeled

.github/workflows/publish.yml

@@ -7,10 +7,74 @@ on:
 
 env:
   REGISTRY: ghcr.io
+  IMAGE_NAME: ${{ github.repository_owner }}/${{ github.event.repository.name }}
 
 jobs:
-  build-and-push:
+  build:
+    runs-on: ${{ matrix.runner }}
+    permissions:
+      contents: read
+      packages: write
+
+    strategy:
+      matrix:
+        runner: [ubuntu-latest, ubuntu-24.04-arm]
+        pg_version: ["17.9", "16.13", "15.17", "14.22"]
+        postgis_version: ["3.6.2"]
+        pgvector_version: ["0.8.2"]
+
+    steps:
+      - name: Checkout repository
+        uses: actions/checkout@v6
+
+      - name: Log in to GitHub Container Registry
+        uses: docker/login-action@v4
+        with:
+          registry: ${{ env.REGISTRY }}
+          username: ${{ github.actor }}
+          password: ${{ secrets.GITHUB_TOKEN }}
+
+      - name: Set up Docker Buildx
+        uses: docker/setup-buildx-action@v4
+
+      - name: Extract metadata (tags, labels) for Docker
+        id: meta
+        uses: docker/metadata-action@v6
+        with:
+          images: ${{ env.REGISTRY }}/${{ env.IMAGE_NAME }}
+
+      - name: Build and push by digest
+        id: build
+        uses: docker/build-push-action@v7
+        with:
+          context: .
+          push: true
+          labels: ${{ steps.meta.outputs.labels }}
+          build-args: |
+            PG_VERSION=${{ matrix.pg_version }}
+            POSTGIS_VERSION=${{ matrix.postgis_version }}
+            PGVECTOR_VERSION=${{ matrix.pgvector_version }}
+          cache-from: type=gha,scope=${{ matrix.pg_version }}-${{ matrix.runner }}
+          cache-to: type=gha,mode=max,scope=${{ matrix.pg_version }}-${{ matrix.runner }}
+          outputs: type=image,push-by-digest=true,name-canonical=true,push=true
+
+      - name: Export digest
+        run: |
+          mkdir -p /tmp/digests
+          digest="${{ steps.build.outputs.digest }}"
+          touch "/tmp/digests/${digest#sha256:}"
+
+      - name: Upload digest
+        uses: actions/upload-artifact@v4
+        with:
+          name: digest-${{ matrix.pg_version }}-${{ matrix.runner }}
+          path: /tmp/digests/*
+          if-no-files-found: error
+          retention-days: 1
+
+  merge:
     runs-on: ubuntu-latest
+    needs: build
     permissions:
       contents: read
       packages: write
@@ -36,8 +100,12 @@ jobs:
             latest: false
 
     steps:
-      - name: Checkout repository
-        uses: actions/checkout@v6
+      - name: Download digests
+        uses: actions/download-artifact@v4
+        with:
+          pattern: digest-${{ matrix.pg_version }}-*
+          merge-multiple: true
+          path: /tmp/digests
 
       - name: Log in to GitHub Container Registry
         uses: docker/login-action@v4
@@ -46,33 +114,19 @@ jobs:
           username: ${{ github.actor }}
           password: ${{ secrets.GITHUB_TOKEN }}
 
-      - name: Set up QEMU
-        uses: docker/setup-qemu-action@v4
-
-      - name: Set up Docker Buildx
-        uses: docker/setup-buildx-action@v4
-
       - name: Extract metadata (tags, labels) for Docker
         id: meta
         uses: docker/metadata-action@v6
         with:
-          images: ${{ env.REGISTRY }}/${{ github.repository_owner }}/${{ github.event.repository.name }}
+          images: ${{ env.REGISTRY }}/${{ env.IMAGE_NAME }}
           tags: |
             type=raw,value=postgres-${{ matrix.pg_version }}-postgis-${{ matrix.postgis_version }}-pgvector-${{ matrix.pgvector_version }}
             type=raw,value=latest,enable=${{ matrix.latest }}
             type=ref,event=tag,enable=${{ matrix.latest }}
 
-      - name: Build and push Docker image
-        uses: docker/build-push-action@v7
-        with:
-          context: .
-          push: true
-          platforms: linux/amd64,linux/arm64
-          tags: ${{ steps.meta.outputs.tags }}
-          labels: ${{ steps.meta.outputs.labels }}
-          build-args: |
-            PG_VERSION=${{ matrix.pg_version }}
-            POSTGIS_VERSION=${{ matrix.postgis_version }}
-            PGVECTOR_VERSION=${{ matrix.pgvector_version }}
-          cache-from: type=gha
-          cache-to: type=gha,mode=max
+      - name: Create multi-arch manifest and push
+        working-directory: /tmp/digests
+        run: |
+          docker buildx imagetools create \
+            $(jq -cr '.tags | map("-t " + .) | join(" ")' <<< "$DOCKER_METADATA_OUTPUT_JSON") \
+            $(printf '${{ env.REGISTRY }}/${{ env.IMAGE_NAME }}@sha256:%s ' *)