Docker buildx for Multi-Platform Image Builds: A Practical Guide

Sep 6
3 min read

Docker buildx to create multi platform docker images.

As cloud-native workloads evolve, developers are building and deploying containers across a variety of architectures — from traditional x86_64 VMs to ARM64-based systems like Raspberry Pi clusters, Apple M-series Macs, and Graviton-powered cloud VMs.

This diversity poses a challenge: how do you build Docker images that run seamlessly across different platforms?

Enter docker buildx — a powerful CLI plugin that enables multi-platform image builds, cross-compilation, and advanced caching strategies.

In this blog, we'll explore:

What is docker buildx?
Why multi-platform builds matter
Step-by-step usage of buildx for multiple architectures
Real-world examples
Tips for CI/CD (including GitHub Actions)

What is docker buildx?

buildx is an extended build command for Docker, based on the BuildKit backend. It brings enhanced functionality to the traditional docker build, including:

Multi-platform builds (linux/amd64, linux/arm64, windows/amd64, etc.)
Build cache export/import
Inline build secrets
Advanced output formats (e.g., OCI)

It's part of Docker CLI as of version 20.10+, and works out of the box with BuildKit enabled.

Why Multi-Platform Builds?

In modern cloud environments like Ananta Cloud, workloads may run on different architectures:

Use Case	Platform
Cloud VMs (Intel/AMD)	linux/amd64
Edge/Raspberry Pi	linux/arm/v7 or linux/arm64
Apple Silicon Dev Machines	linux/arm64
Serverless (FaaS) containers	Often arm64

Building a single image for one platform can lead to compatibility issues or runtime failures on others. Multi-platform images ensure:

✅ Portability

✅ Consistency across dev, test, and prod

✅ Reduced complexity in pipelines

Prerequisites

To get started, make sure your system has:

Docker 20.10 or higher
buildx plugin (usually pre-installed)
QEMU emulation for cross-platform builds

Install QEMU with:


docker run --privileged --rm tonistiigi/binfmt --install all

Step-by-Step: Multi-Platform Build with buildx

01 - Create a New Builder Instance


docker buildx create --name ananta-builder --use
docker buildx inspect --bootstrap

This sets ananta-builder as your active builder.

02 - Write a Simple Dockerfile


# Dockerfile
FROM alpine
RUN echo "Hello from Ananta Cloud!" > /message.txt
CMD ["cat", "/message.txt"]

03 - Build for Multiple Platforms


docker buildx build \
  --platform linux/amd64,linux/arm64 \
  -t anantacloud/hello-multiarch:1.0 \
  --push \
  .

This command builds the image for two platforms and pushes it to Docker Hub.

--push is required for multi-arch because multi-platform images cannot be loaded into local Docker.

04 - Inspect the Image


docker buildx imagetools inspect anantacloud/hello-multiarch:latest

You’ll see output like:


Name:      docker.io/anantacloud/hello-multiarch:v1.0
Platforms:
  - linux/amd64
  - linux/arm64

GitHub Actions Example

Here's a simple GitHub Actions workflow to build and push a multi-platform image:


name: Build and Push Multi-Arch Docker Image

on:
  push:
    branches: [ main ]

jobs:
  build:
    runs-on: ubuntu-latest
    steps:
      - uses: actions/checkout@v3
      
      - name: Set up QEMU
        uses: docker/setup-qemu-action@v3

      - name: Set up Docker Buildx
        uses: docker/setup-buildx-action@v3

      - name: Login to Docker Hub
        uses: docker/login-action@v3
        with:
          username: ${{ secrets.DOCKER_USERNAME }}
          password: ${{ secrets.DOCKER_PASSWORD }}

      - name: Build and Push
        uses: docker/build-push-action@v5
        with:
          context: .
          push: true
          tags: anantacloud/hello-multiarch:v1.0
          platforms: linux/amd64,linux/arm64

Pro Tips

01 - Local Test (Single Platform)

Use --load if you want to load the image into your local Docker engine:


docker buildx build \
  --platform linux/amd64 \
  -t hello-local:latest \
  --load \
  .

⚠️ --load works for single platform only.

02 - Optimize with Caching


docker buildx build \
  --platform linux/amd64,linux/arm64 \
  --cache-to=type=inline \
  --cache-from=type=registry,ref=your-cache-image \
  ...

Use this for faster CI builds.

Where Multi-Arch Matters?

Ananta Cloud supports running containers across a wide range of hardware — from edge devices to cloud-native ARM64 VMs. With buildx, you can:

Ship the same container to any Ananta region or architecture
Reduce complexity in hybrid deployments
Build once, run anywhere — truly

Conclusion

docker buildx is no longer a niche tool — it's an essential part of any modern container build pipeline. By leveraging multi-platform builds, you're future-proofing your applications for any architecture, reducing manual work, and improving the consistency of your deployments across environments.

At Ananta Cloud, we’re committed to helping developers and ops teams build portable, high-performance, and cross-architecture container workflows. If you haven't tried buildx yet — now's the time!

✉️ Have Questions?

Reach out to the Ananta Cloud team to discuss this further — we’d love to hear how you're using multi-platform containers.

Email: hello@anantacloud.com | LinkedIn: @anantacloud | Schedule Meeting