A reference to a filesystem tree. For example: - The root filesystem of a container - A source code repository - A directory containing binary artifacts Rule of thumb: if it fits in a tar archive, it fits in a #FS.
Container image config. See [OCI](https://opencontainers.org/). Spec left open on purpose to account for additional fields. [Image Spec](https://github.com/opencontainers/image-spec/blob/main/specs-go/v1/config.go) [Docker Superset](https://github.com/moby/buildkit/blob/master/frontend/dockerfile/dockerfile2llb/image.go)
A reference to an external secret, for example: - A password - A SSH private key - An API token Secrets are never merged in the Cue tree. They can only be used by a special filesystem mount designed to minimize leak risk.
### engine.#Secret Inputs
_No input._
### engine.#Secret Outputs
_No output._
## engine.#Service
A reference to a network service endpoint, for example: - A TCP or UDP port - A unix or npipe socket - An HTTPS endpoint