[MESOS-6899] Document the unified containerizer image pulling `cached` option.

• Type: Documentation
• Status: Open
• Priority: Major
• Resolution: Unresolved
• Component/s: containerization, documentation
• Labels: containerizer document
• Assignee: Unassigned
• Reporter: Gilbert Song
• Created: 10/Jan/17 11:18
• Updated: 10/Jan/17 11:19

Description

In docker containerizer, there is a `force_pull_image` option to force the image being pulled overwriting the existing image in docker daemon.

Correspondingly, in unified containerizer, both docker and appc store support this option (named as `cached` in protobuf), which overwrites existing image layers.

We should document this option in unified containerizer.