Primitives

The domain objects that show up across many subsystems. Each has its own canonical home in the codebase but is referenced from the API, the daemon, the builder, swarm, libnetwork, and storage.

Primitive	Home	Touched by
Container	daemon/container/	Daemon, server, builder, swarm executor.
Image	daemon/internal/image/, daemon/containerd/	Image service, builder, distribution, plugins.
Layer	daemon/internal/layer/	Legacy image store, graphdrivers, distribution.
Network / Sandbox / Endpoint	daemon/libnetwork/	Daemon container start/stop, swarm, plugins, server.
Volume / Mount	daemon/volume/	Daemon container start, swarm executor, plugins.
Service / Task	daemon/cluster/, api/types/swarm/	Swarm cluster, libnetwork (overlay), executor.

These primitives are deliberately minimal: most are plain Go structs in the api/types/<area>/ packages so they can travel over the wire without translation.