fix: Move docker builds to native platforms

The current Docker builds are taking an excessively long time to complete,
currently over 6 hours causing GitHub Actions to time out. We believe
it's because internally it's using virtualization to build the arm64
version of the container.

To attempt to alleviate this, this PR uses a GitHub Actions matrix to
separate the builds into runners on their own native platforms.

The hope is that the lack of needing to virtualize will speed up the
overall time.

Author: clintjedwards

.github/workflows/docker-publish.yml

@@ -11,36 +11,122 @@ env:
 
 jobs:
   build:
-    runs-on: ubuntu-latest
+    # We use a matrix to run each docker container build for a specific platform on it's own native runner.
+    # This avoids using virtualization and massively speeds up builds.
+    strategy:
+      matrix:
+        platform: [linux/amd64, linux/arm64]
+        include:
+          - platform: linux/amd64
+            runner: ubuntu-latest
+          - platform: linux/arm64
+            runner: ubuntu-24.04-arm
+
+
+    name: Build ${{ matrix.platform }}
+    runs-on: ${{ matrix.runner }}
     steps:
-      - name: Checkout
+      - name: Code checkout
         uses: actions/checkout@v4
+
       - name: Set up Docker Buildx
         uses: docker/setup-buildx-action@v3
+
       - name: Get source version
-        run: echo "SOURCE_VERSION=$(grep VERSION compose.yaml | awk {'print $2'})" >> "$GITHUB_ENV"
+        run: echo "SOURCE_VERSION=$(grep VERSION compose.yaml | awk '{print $2}')" >> "$GITHUB_ENV"
+
       - name: Docker meta
         id: meta
         uses: docker/metadata-action@v5
         with:
           images: ${{ env.REGISTRY }}/${{ env.IMAGE_NAME }}
+          flavor: |
+            latest=false
           tags: |
-            type=ref,event=branch
-            type=semver,pattern={{version}}
-      - name: Login to registry ${{ env.REGISTRY }}
+            type=ref,event=branch,pattern={{branch}}
+            type=semver,pattern={{version}},value=${{ env.SOURCE_VERSION }}
+
+      - name: Derive arch-suffixed tags as output
+        id: archtags
+        run: |
+          set -euo pipefail
+          ARCH="$(echo '${{ matrix.platform }}' | cut -d/ -f2)"
+          T="$(printf '%s\n' "${{ steps.meta.outputs.tags }}" | sed "s/$/-${ARCH}/")"
+          {
+            echo 'tags<<EOF'
+            echo "$T"
+            echo 'EOF'
+            echo "arch=$ARCH"
+          } >> "$GITHUB_OUTPUT"
+
+      - name: Login to ${{ env.REGISTRY }}
         if: github.event_name != 'pull_request'
         uses: docker/login-action@v3
         with:
           registry: ${{ env.REGISTRY }}
           username: ${{ secrets.DOCKER_USERNAME }}
           password: ${{ secrets.DOCKER_PASSWORD }}
-      - name: Build and push
-        uses: docker/build-push-action@v5
+
+      - name: Build & push ${{ matrix.platform }}
+        uses: docker/build-push-action@v6
         with:
           context: .
+          platforms: ${{ matrix.platform }}
+          push: ${{ github.event_name != 'pull_request' }}
           build-args: |
             VERSION=${{ env.SOURCE_VERSION }}
-          platforms: linux/amd64,linux/arm64
-          push: ${{ github.event_name != 'pull_request' }}
-          tags: ${{ steps.meta.outputs.tags }}
+          tags: ${{ steps.archtags.outputs.tags }}
           labels: ${{ steps.meta.outputs.labels }}
+
+  # In order to have a single tag that covers both archtectures we run one more job to create a multi-arch manifest
+  # under a single tag.
+  manifest:
+    name: Create multi-arch manifest
+    runs-on: ubuntu-latest
+    needs: build
+    steps:
+      - name: Code checkout
+        uses: actions/checkout@v4
+
+      - name: Get source version
+        run: echo "SOURCE_VERSION=$(grep VERSION compose.yaml | awk '{print $2}')" >> "$GITHUB_ENV"
+
+      - name: Docker meta (same base tags)
+        id: meta
+        uses: docker/metadata-action@v5
+        with:
+          images: ${{ env.REGISTRY }}/${{ env.IMAGE_NAME }}
+          flavor: |
+            latest=false
+          tags: |
+            type=ref,event=branch,pattern={{branch}}
+            type=semver,pattern={{version}},value=${{ env.SOURCE_VERSION }}
+
+      - name: Login
+        uses: docker/login-action@v3
+        with:
+          registry: ${{ env.REGISTRY }}
+          username: ${{ secrets.DOCKER_USERNAME }}
+          password: ${{ secrets.DOCKER_PASSWORD }}
+
+      - name: Create manifest for each base tag
+        if: github.event_name != 'pull_request'
+        run: |
+          set -euo pipefail
+          while IFS= read -r BASE; do
+            echo "Preparing manifest for $BASE"
+            AMD="${BASE}-amd64"
+            ARM="${BASE}-arm64"
+            # Skip if one arch is missing
+            docker buildx imagetools inspect "$AMD"
+            docker buildx imagetools inspect "$ARM"
+
+            docker buildx imagetools create \
+              --tag "$BASE" \
+              "$AMD" \
+              "$ARM"
+
+            echo "OK: $BASE now points to $AMD + $ARM"
+          done <<'EOF'
+          ${{ steps.meta.outputs.tags }}
+          EOF