Write about App Container specification in Rocket containerization.
Rocket is a command line tool, rkt, that implements the App Container specification created by CoreOS for an open portable container format, composed of:
App Container Image (ACI): Signed and optionally encrypted tgz with all the bits to run the container. Encryption allows distribution via BitTorrent, public object storage, or mirror networks.
App Container runtime: Environment in which the container should run, including devices, environment variables, privileges and a definition of a meta-data service interface for exposing data to the environment from outside the container.
App Container discovery: Federated protocol for finding and downloading images, inspired by golang’s vanity URL convention for import paths. Images can referred to with names such as coreos.com/etcd, allowing federated downloads without running a registry.