Master Multi‑Architecture Docker Images with Buildx: A Step‑by‑Step Guide

What Is Docker Buildx?

Docker Buildx is an official Docker CLI plugin that extends Docker’s build capabilities, allowing developers to create multi‑platform images (e.g., AMD64, ARM) and handle more complex build scenarios.

Key Features

Multi‑platform image building : Generate images for different CPU architectures and operating systems from a single build.

Builder instance management : Create and manage multiple builder instances, each with its own configuration, which is useful for CI/CD pipelines.

Distributed builds : Combine remote build nodes to accelerate large projects.

Configuring the Docker Buildx Environment

Prerequisites

Docker version 19.03 or newer

Kernel version 4.8 or newer

Download Buildx Plugin

<code>$ sudo mkdir -p /root/.docker/cli-plugins
$ sudo curl -L -o /root/.docker/cli-plugins/docker-buildx https://github.com/docker/buildx/releases/download/v0.20.1/buildx-v0.20.1.linux-amd64
$ sudo chmod +x /root/.docker/cli-plugins/docker-buildx
$ docker buildx version</code>

Create a Builder Instance

<code># Builder configuration
cat <<'EOF' | tee /tmp/buildkitd.toml > /dev/null
debug = true
[registry."docker.io"]
  mirrors = ["https://docker.xuanyuan.me"]
[registry."core.jiaxzeng.com"]
  ca=["/etc/docker/certs.d/core.jiaxzeng.com/ca.crt"]
EOF

# Create builder
sudo docker buildx create --use --name mybuilder --driver docker-container --config /tmp/buildkitd.toml

# Inspect and bootstrap
sudo docker buildx inspect --bootstrap</code>

Building Multi‑Architecture Images

<code># Add host entry for private registry
sudo docker exec -it buildx_buildkit_mybuilder0 sh
/ # echo '172.139.20.100 core.jiaxzeng.com' >> /etc/hosts
/ # exit

# Prepare a simple Dockerfile
mkdir client && cd client && echo "FROM ubuntu:24.10" > Dockerfile

# Build and push AMD64 & ARM64 images
sudo docker buildx build --platform linux/amd64,linux/arm64 -t core.jiaxzeng.com/jiaxzeng/ubuntu:24.10 . --push</code>

Tips

Configure DNS for private registries.

Log in to the registry on the host.

Trust the private registry’s certificate on the host.

Conclusion

Using Docker Buildx to build multi‑platform images simplifies developers’ workflows and ensures applications run reliably across diverse environments. As container and cloud‑native technologies evolve, Buildx is expected to introduce more innovative features that further accelerate containerization and meet varied business needs.