Docker WSL: Building ARM and x86 Images Simultaneously – A Step-by-Step Guide

Are you tired of switching between different environments to build Docker images for ARM and x86 architectures? Do you wish you could build both images simultaneously, saving you time and effort? Well, you’re in luck! With Docker WSL (Windows Subsystem for Linux), you can do just that. In this article, we’ll take you through a step-by-step guide on how to build Docker images for both ARM and x86 architectures in the same project, using Docker WSL.

Prerequisites

Before we dive into the tutorial, make sure you have the following prerequisites met:

• Windows 10 or later with WSL 2 enabled
• Docker Desktop installed and running
• A Linux distribution installed on WSL (e.g., Ubuntu, Debian, or Kali Linux)
• Familiarity with Docker and Dockerfiles

Understanding the Challenge

Building Docker images for different architectures can be a challenge, especially when you need to build for both ARM and x86. The main issue lies in the fact that ARM and x86 have different instruction sets, which means you need to compile your code twice – once for each architecture. This can lead to duplicated efforts, increased build times, and maintenance headaches.

The Solution: Docker WSL and Multi-Architecture Builds

Docker WSL provides a solution to this problem by allowing you to run multiple architectures simultaneously. With Docker WSL, you can build Docker images for ARM and x86 architectures in the same project, using a single Dockerfile. This approach eliminates the need for duplicated efforts and reduces build times.

Setting Up the Environment

Before we start building our Docker images, let’s set up our environment:

# Open a new terminal in your WSL Linux distribution
$ cd ~
$ mkdir multi-arch-build
$ cd multi-arch-build

Create a new file called `Dockerfile` in the `multi-arch-build` directory:

touch Dockerfile

Writing the Dockerfile

The Dockerfile is the heart of our build process. Here’s an example Dockerfile that builds a simple Python application for both ARM and x86 architectures:

FROM python:3.9-slim as base

# Set the working directory
WORKDIR /app

# Copy the requirements file
COPY requirements.txt .

# Install the dependencies
RUN pip install -r requirements.txt

# Copy the application code
COPY . .

# Set the environment variables
ENV PYTHONDONTWRITEBYTECODE 1
ENV PYTHONUNBUFFERED 1

# Expose the port
EXPOSE 8000

# Run the command to start the application
CMD ["python", "app.py"]

This Dockerfile uses a multi-stage build process, where we first build the application for ARM and then for x86. We use the `as` keyword to define two stages: `arm` and `amd64` (for x86). We then use the `FROM` instruction to specify the base image for each stage.

Building for ARM

FROM arm32v7/python:3.9-slim as arm
WORKDIR /app
COPY requirements.txt .
RUN pip install -r requirements.txt
COPY . .
ENV PYTHONDONTWRITEBYTECODE 1
ENV PYTHONUNBUFFERED 1
EXPOSE 8000
CMD ["python", "app.py"]

Building for x86

FROM amd64/python:3.9-slim as amd64
WORKDIR /app
COPY requirements.txt .
RUN pip install -r requirements.txt
COPY . .
ENV PYTHONDONTWRITEBYTECODE 1
ENV PYTHONUNBUFFERED 1
EXPOSE 8000
CMD ["python", "app.py"]

Building the Docker Images

Now that we have our Dockerfile, let’s build the Docker images for both ARM and x86 architectures:

# Build the ARM image
$ docker build --platform=linux/arm/v7 -t my-arm-app .

# Build the x86 image
$ docker build --platform=linux/amd64 -t my-x86-app .

The `–platform` flag specifies the target platform for the build process. In this case, we’re building for `linux/arm/v7` and `linux/amd64`.

Pushing the Images to Docker Hub

Once the build process is complete, you can push the images to Docker Hub:

# Push the ARM image
$ docker tag my-arm-app:latest /my-arm-app:latest
$ docker push /my-arm-app:latest

# Push the x86 image
$ docker tag my-x86-app:latest /my-x86-app:latest
$ docker push /my-x86-app:latest

Replace `` with your actual Docker Hub username.

Conclusion

In this article, we’ve shown you how to build Docker images for both ARM and x86 architectures simultaneously using Docker WSL. By using a single Dockerfile and the `–platform` flag, you can build and push images for multiple architectures in a single step. This approach saves you time and effort, and eliminates the need for duplicated efforts.

With Docker WSL, you can take advantage of the power of multi-architecture builds and simplify your development workflow. So, what are you waiting for? Try it out today and start building your own multi-architecture Docker images!

Architecture	Image Name	Platform
ARM	my-arm-app	linux/arm/v7
x86	my-x86-app	linux/amd64

This table summarizes the architectures, image names, and platforms used in this tutorial.

Frequently Asked Question

Get ready to revolutionize your development workflow with Docker WSL build for ARM and x86!