Image cache

An image cache is the set of sandbox images already stored on a host, which lets a sandbox start there without a pull.

An image cache holds the sandbox images that are already stored on a host. The sandbox runtime builds the root filesystem of a new sandbox as a copy-on-write view over a base image on the host. When the base image is already on the host, creation costs almost nothing. A cold image on a host means a pull before the first start.