How should one back up Docker Trusted Registry (DTR) metadata?

Backing up Docker Trusted Registry (DTR) metadata using the method of running a container from the DTR image with the backup command is the correct approach because it ensures that the backup process follows the prescribed and supported backup methodology provided by Docker. When utilizing the specified backup command within the DTR container, it automatically handles the nuances of the metadata structure, keeping the integrity and consistency of the data intact during the backup operation.

This method integrates with the DTR's existing architecture and leverages built-in tools to safely and effectively capture the metadata without risking corruption or loss of important data. The process is designed to account for any possible dependencies or configurations within the registry setup, leading to a more reliable backup.

In contrast, the other methods like manually copying metadata files or utilizing the Docker CLI to save the metadata come with significant risks. Manually copying files can lead to incomplete backups or the omission of crucial files, as the user may not know all the dependencies or changes in the metadata structure. Similarly, exporting metadata to a JSON file may not capture all the necessary configurations or states needed for a complete restoration, as it might only address visible or explicit data rather than the underlying setup essential for a fully functional rollback.