Docker has revolutionized the way we deploy and manage applications by providing a standardized platform for building, shipping, and running applications. Docker containers are lightweight, portable, and secure, which makes them ideal for deploying applications across different platforms and architectures.
In this blog post, we will walk you through the steps required to build a Docker container on an ARM architecture for an i386 platform using Docker Buildx. Additionally, we will explain how to push the container directly to Docker Hub.
Before we begin, make sure that you have the following prerequisites installed:
- Docker Engine (version 19.03 or higher) and Docker CLI
- Docker Buildx plugin (version 0.5.1 or higher)
- An ARM-based system Mac M1 to build the container on
- An i386-based system to run the container on
Building a Docker container on ARM architecture
To build a Docker container on ARM architecture, we will use Docker Buildx, which is a CLI plugin that extends the Docker CLI with the ability to build and push images to multiple platforms and architectures.
- Start by creating a new Dockerfile in your project directory. In this example, we will be building a simple Node.js web application.
FROM arm32v7/node:14-alpine WORKDIR /app COPY package*.json ./ RUN npm install COPY . . EXPOSE 3000 CMD ["npm", "start"]
- Initialize a new builder instance with Docker Buildx by running the following command:
docker buildx create --name mybuilder --use
This will create a new builder instance named “mybuilder” and set it as the active builder.
- Set the builder instance to support the ARM architecture by running the following command:
docker buildx build --platform linux/arm/v7 -t your-dockerhub-username/myapp:arm .
This command tells Docker Buildx to build the image for the ARM architecture and tag it with the specified Docker Hub username and repository name.
- Once the build is complete, you can verify that the image was built correctly by running the following command:
This will display a list of all the images on your system, including the newly built ARM-based image.
Pushing the Docker container to Docker Hub
Now that we have built the Docker container for the ARM architecture, we can push it to Docker Hub and make it available for others to use.
- Login to Docker Hub using the Docker CLI by running the following command:
- Tag the ARM-based image with the i386 architecture by running the following command:
docker buildx build --platform linux/amd64,linux/arm/v7 -t your-dockerhub-username/myapp:latest --push .
This command tells Docker Buildx to build the image for both the i386 and ARM architectures and push it to Docker Hub.
- Verify that the image was pushed to Docker Hub by visiting the Docker Hub website and checking your repository.
Congratulations! You have successfully built and pushed a Docker container on an ARM architecture for an i386 platform using Docker Buildx. This technique can be used to build and deploy containers for any combination of platforms and architectures.