Building Multi-Arch Docker Images with Buildah

Buildah serves as a command-line tool for creating Open Container Initiative (OCI) images compatible with Docker, Kubernetes, and other container systems. Unlike Docker, it operates without requiring a daemon, offering a lightweight alternative for container image creation.

Why Use Buildah?

Daemon-less: Operates without a daemon, enhancing security and reducing resource overhead
Flexibility: Integrates seamlessly with existing CI/CD pipelines
Multi-Arch Support: Enables building images for different architectures without separate configurations

Installing Buildah

On Ubuntu systems, installation requires:

sudo apt-get update
sudo apt-get install -y buildah qemu-user-static

For other distributions, consult the official Buildah installation documentation.

Building Multi-Architecture Images

Step 1: Set Up QEMU

Enable cross-architecture building using QEMU emulation:

docker run --rm --privileged multiarch/qemu-user-static --reset -p yes

Alternatively, with Podman:

podman run --rm --privileged multiarch/qemu-user-static --reset -p yes

Step 2: Prepare Your Dockerfile

Create a Dockerfile for your application. Example using Alpine Linux with development tools:

FROM alpine:3.20.0
RUN apk add --no-cache \
    bash \
    curl \
    wget \
    vim \
    nano \
    htop \
    tcpdump \
    nmap \
    git \
    jq \
    netcat-openbsd \
    bind-tools \
    traceroute
CMD ["/bin/bash"]

Step 3: Build Images for Each Architecture

Generate separate images for both amd64 and arm64:

# Build image for amd64
buildah bud --arch amd64 -f Dockerfile -t dimjones/toolbox:amd64 .

# Build image for arm64
buildah bud --arch arm64 -f Dockerfile -t dimjones/toolbox:arm64 .

Step 4: Create a Multi-Architecture Manifest

Combine both architecture images into a single manifest:

# Create a new manifest
buildah manifest create dimjones/toolbox:latest

# Add the images to the manifest
buildah manifest add dimjones/toolbox:latest dimjones/toolbox:amd64
buildah manifest add dimjones/toolbox:latest dimjones/toolbox:arm64

Step 5: Push the Multi-Architecture Image

Upload the multi-architecture manifest to your Docker registry:

buildah manifest push --all dimjones/toolbox:latest docker://dimjones/toolbox:latest

Conclusion

Buildah enables efficient multi-architecture container image creation without Docker’s daemon dependency. This approach streamlines builds, reduces system dependencies, and eliminates the security overhead of running a daemon — making it ideal for cloud and edge computing environments.