Fix multi-platform buildx error in GitHub Actions

- Fixed "docker exporter does not support manifest lists" error
- Multi-platform builds now use --output type=image instead of --load
- Single platform builds continue to use --load for local Docker daemon
- CI workflow now builds for single platform to enable testing
- Added separate workflow for testing multi-arch builds
- Updated tests and documentation to reflect the behavior differences

The issue was that --load only works for single platform builds since
the local Docker daemon can only store images for one architecture.

🤖 Generated with Claude Code

Co-Authored-By: Claude <[email protected]>

Author: Hat Dao

.github/workflows/dockerimage.yml

@@ -24,9 +24,9 @@ jobs:
           
       - name: Build multi-architecture images
         run: |
-          # Build for both amd64 and arm64
-          # Note: --no-push flag is used instead of --push=False
-          invoke buildx latest --no-push
+          # For CI testing, build only for the current platform (amd64)
+          # This allows us to use --load and test the image
+          invoke buildx latest --no-push --platforms="linux/amd64"
           
       - name: Test the built image
         run: |

.github/workflows/test-multiarch.yml

@@ -0,0 +1,43 @@
+name: Test Multi-Architecture Build
+
+on:
+  pull_request:
+    paths:
+      - 'Dockerfile'
+      - 'tasks.py'
+      - '.github/workflows/test-multiarch.yml'
+  workflow_dispatch:
+
+jobs:
+  test-multiarch-build:
+    runs-on: ubuntu-latest
+    strategy:
+      matrix:
+        version: ['latest', '7.2.5', '7.0.15']
+    steps:
+      - uses: actions/checkout@v4
+      
+      - name: Set up QEMU
+        uses: docker/setup-qemu-action@v3
+        
+      - name: Set up Docker Buildx
+        uses: docker/setup-buildx-action@v3
+        
+      - name: Install Python dependencies
+        run: |
+          python -m pip install --upgrade pip
+          pip install invoke requests
+          
+      - name: Test multi-architecture build (without push)
+        run: |
+          # Test building for both platforms
+          # This validates that the build works for ARM64
+          invoke buildx ${{ matrix.version }} --no-push
+          
+      - name: Build and test single platform
+        run: |
+          # Build for current platform only so we can test it
+          invoke buildx ${{ matrix.version }} --no-push --platforms="linux/amd64"
+          
+          # Test the image
+          docker run --rm grokzen/redis-cluster:${{ matrix.version }} redis-server --version

README.md

@@ -242,17 +242,17 @@ To build multi-architecture images locally, you need Docker Buildx (included in
     # Build and push to Docker Hub (default behavior)
     invoke buildx 7.2.5
 
-    # Build without pushing (for local testing)
+    # Build without pushing (for validation only - images won't be loaded locally)
     invoke buildx 7.2.5 --no-push
 
-    # Build for specific platforms only
-    invoke buildx 7.2.5 --platforms="linux/amd64"
+    # Build for current platform only (will be loaded to local Docker)
+    invoke buildx 7.2.5 --no-push --platforms="linux/amd64"
 
     # Build all versions for multi-arch
     invoke buildx all
 
-    # Build without pushing for a specific platform
-    invoke buildx 7.2.5 --no-push --platforms="linux/arm64"
+    # Build and load for local testing (single platform only)
+    invoke buildx 7.2.5 --no-push --platforms="linux/$(uname -m | sed 's/x86_64/amd64/;s/aarch64/arm64/')"
 
 #### Using docker buildx directly
 

__pycache__/tasks.cpython-312.pyc

@@ -169,7 +169,20 @@ def _docker_buildx(config):
     Internal multiprocess method to run docker buildx command
     """
     c, version, platforms, push = config
-    action = "--push" if push else "--load"
+    
+    if push:
+        action = "--push"
+    else:
+        # For local builds, we need to handle single vs multi-platform differently
+        platform_list = platforms.split(',')
+        if len(platform_list) == 1:
+            # Single platform: can use --load
+            action = "--load"
+        else:
+            # Multi-platform: use --output type=docker,dest=-
+            # This outputs to stdout which we'll discard, but allows the build to complete
+            action = "--output type=image"
+    
     print(f" -- Starting docker buildx for version : {version} on platforms: {platforms} with action: {action}")
     build_command = f"docker buildx build --platform={platforms} --build-arg redis_version={version} -t grokzen/redis-cluster:{version} {action} ."
     c.run(build_command)

__pycache__/test_tasks.cpython-312.pyc

@@ -85,13 +85,24 @@ def test_docker_buildx_push_true(self):
         expected_cmd = "docker buildx build --platform=linux/amd64,linux/arm64 --build-arg redis_version=7.2.5 -t grokzen/redis-cluster:7.2.5 --push ."
         self.mock_context.run.assert_called_with(expected_cmd)
 
-    def test_docker_buildx_push_false(self):
-        """Test _docker_buildx with push=False"""
+    def test_docker_buildx_push_false_multiplatform(self):
+        """Test _docker_buildx with push=False for multi-platform"""
         config = [self.mock_context, "7.2.5", "linux/amd64,linux/arm64", False]
 
         tasks._docker_buildx(config)
 
-        expected_cmd = "docker buildx build --platform=linux/amd64,linux/arm64 --build-arg redis_version=7.2.5 -t grokzen/redis-cluster:7.2.5 --load ."
+        # Multi-platform builds use --output type=image instead of --load
+        expected_cmd = "docker buildx build --platform=linux/amd64,linux/arm64 --build-arg redis_version=7.2.5 -t grokzen/redis-cluster:7.2.5 --output type=image ."
+        self.mock_context.run.assert_called_with(expected_cmd)
+        
+    def test_docker_buildx_push_false_single_platform(self):
+        """Test _docker_buildx with push=False for single platform"""
+        config = [self.mock_context, "7.2.5", "linux/amd64", False]
+        
+        tasks._docker_buildx(config)
+        
+        # Single platform builds can use --load
+        expected_cmd = "docker buildx build --platform=linux/amd64 --build-arg redis_version=7.2.5 -t grokzen/redis-cluster:7.2.5 --load ."
         self.mock_context.run.assert_called_with(expected_cmd)
 
     @patch('tasks.Pool')