Create a reusable Docker image that supports multiple platforms

To create a reusable Docker image that supports multiple platforms (arm64, amd64), you can follow these steps to dump your current modified container into a reusable multi-platform image.

We’ll use Docker Buildx for this purpose, which enables multi-platform builds. Here’s a step-by-step guide:

Step 1: Install Docker Buildx

Ensure you have Docker Buildx installed. Docker Buildx is included in Docker Desktop, but if you’re using Docker Engine, you might need to enable the Buildx feature.

docker buildx version

Step 2: Create a New Builder Instance

Create a new builder instance and set it as the default.

docker buildx create --name mybuilder --use
docker buildx inspect mybuilder --bootstrap

Step 3: Commit Your Current Container

First, commit your running container to a new image. Replace container_id with your actual container ID and new_image_name with your desired image name.

docker commit container_id new_image_name:latest

Step 4: Write a Dockerfile (if not already existing)

If you already have a Dockerfile, ensure it’s optimized for multi-platform builds. If not, create a Dockerfile based on your committed container.

# Dockerfile
FROM new_image_name:latest

Step 5: Build the Multi-Platform Image

Use Docker Buildx to build and push the image for multiple platforms. Replace your_dockerhub_username with your Docker Hub username and your_repo_name with your repository name.

docker buildx build --platform linux/amd64,linux/arm64 -t your_dockerhub_username/your_repo_name:latest --push .

Complete Example

Here’s a complete example assuming I have committed my container as traffic and want to build a multi-platform image.

1. Install Buildx and create a builder instance:

docker buildx create --name mybuilder --use
docker buildx inspect mybuilder --bootstrap

2. Commit the container:

docker commit traffic traffik:latest

3. Create a Dockerfile:

# Dockerfile
FROM traffik:latest

4. Build and push the multi-platform image:

docker buildx build --platform linux/amd64,linux/arm64 -t ngtrthanh/traffiq:latest --push .

Notes:

• Ensure that the Dockerfile and committed image are correctly set up.
• The --push flag in the docker buildx build command pushes the built images directly to Docker Hub.
• Add more platforms as needed by appending them to the --platform flag.

This approach helps to create a multi-platform Docker image from my current container, making it reusable across different architectures.