A manifest file, or manifest, is a file containing metadata for a group of files that are part of a set unit.
For example, a manifest file could store information about a container image. You can access additional information through the Docker manifest command.
You can delete untagged manifests using doctl, which can free up space in your registry. However, after you delete a manifest, you cannot reference its corresponding layer data.
If you have untagged image manifests, you can delete them during garbage collection. This is ideal to free up even more storage in your repositories. We recommend including the --include-untagged-manifests option or checking Delete untagged manifests in the control panel, since this also deletes untagged manifests, maximizing the amount of space freed by the garbage collection. For detailed steps, see our guide, How to Free Up Space in Your Container Registry.