Scenario:

You have a Dockerfile at /home/interview/Dockerfile that needs to be built for multiple architectures to support different hardware platforms. Currently, building with docker build only creates images for the host architecture.

Task:

Configure Docker Buildx instance named multiarch with buildx create to build the image for both amd64 and arm64 architectures using Push the multi-arch manifest to localhost:5000/myapp:multi.

Example:

Building for linux/amd64 only

Building for linux/amd64, linux/arm64
Pushing manifest list to localhost:5000/myapp:multi

Step 1: List existing builders

docker buildx ls

See available builder instances.

Step 2: Create a new builder instance for multi-arch

docker buildx create --name multiarch --driver docker-container --driver-opt network=host --use

Create and activate a builder with container driver and host network access.

Step 3: Bootstrap the builder

docker buildx inspect --bootstrap

Initialize the builder instance.

Step 4: Build for multiple architectures and push

cd /home/interview && docker buildx build \
  --platform linux/amd64,linux/arm64 \
  -t localhost:5000/myapp:multi \
  --push \
  .

Build for both platforms and push manifest list.

Step 5: Verify the manifest was pushed

docker buildx imagetools inspect localhost:5000/myapp:multi

Shows the manifest list with both architectures.

Step 6: Pull the image (auto-selects architecture)

docker pull localhost:5000/myapp:multi

Pulls the image matching the current host architecture.

Step 7: Verify the pulled image architecture

docker image inspect localhost:5000/myapp:multi --format '{{.Architecture}}'

Should show the host's architecture (amd64 or arm64).