EachBackend calls a given function for each registered backend.

NewBackendProvider looks up a backend by its alias and returns a provider via the factory func on the registered *Backend.

Register adds a backend to the registry!.

DockerMinSupportedAPIVersion of 1.24 means the client library in use here can only support docker-engine 1.12 and above (https://docs.docker.com/release-notes/docker-engine/#1120-2016-07-28).

ErrMissingEndpointConfig is returned if the provider config was missing an 'ENDPOINT' configuration, but one is required.

ErrStaleVM is returned from one of the Instance methods if it detects that the VM had already been used for a repository and was not reverted afterwards.

Backend wraps up an alias, backend provider help, and a factory func for a given backend provider wheee.

RunResult represents the result of running a script with Instance.RunScript.

StartAttributes contains some parts of the config which can be used to determine the type of instance to boot up (for example, what image to use).

An Instance is something that can run a build script.

Provider represents some kind of instance provider.