This project provides a GitHub Actions workflow to automatically pull a specified Docker image and push it to the GitHub Container Registry (GHCR), with a focus on supporting users who utilize the container command on macOS.

The main goal of this project is to make popular container images easily accessible and compatible for macOS users, especially those using the container command. By mirroring images to GHCR, macOS users can benefit from improved reliability and performance when pulling images.

1. How to Trigger

   • On push to the main branch (excluding changes to README.md)
   • Manually via the GitHub Actions workflow_dispatch event, with the option to specify the image to sync

2. Customizing the Image
   When running the workflow manually from the Actions tab, you can specify the image to sync using the image_to_sync input (e.g., ubuntu:latest).
   The default image is ubuntu:latest.

3. Sync Process

   • Pulls the specified Docker image (for the linux/arm64 platform, which is compatible with Apple Silicon Macs)
   • Extracts the image name and tag
   • Retags the image for GHCR as:
     ghcr.io/<github-username>/<repository-name>/<image-name>:<tag>
   • Pushes the image to GHCR

4. Example
   If you specify nginx:alpine, the resulting image will be available at:

   ghcr.io/<your-github-username>/<repository-name>/nginx:alpine
   

• Designed for macOS users, especially those using the container command
• Requires the repository's GITHUB_TOKEN (enabled by default)
• The workflow runs on ubuntu-latest
• Only public images are supported for syncing
• The image tag will always be converted to lowercase when syncing to GHCR