This section defines a format for encoding a container as a filesystem bundle - a set of files organized in a certain way, and containing all the necessary data and metadata for any compliant runtime to perform all standard operations against it. See also OS X application bundles for a similar use of the term bundle.
The definition of a bundle is only concerned with how a container, and its configuration data, are stored on a local filesystem so that it can be consumed by a compliant runtime.
A Standard Container bundle contains all the information needed to load and run a container. This MUST include the following artifacts:
A directory representing the root filesystem of the container. While the name of this REQUIRED directory may be arbitrary, users should consider using a conventional name, such as
rootfs. This directory MUST be referenced from within the
While these artifacts MUST all be present in a single directory on the local filesystem, that directory itself is not part of the bundle. In other words, a tar archive of a bundle will have these artifacts at the root of the archive, not nested within a top-level directory.