Image scanning, signing, and provenance answer different questions. Scanning asks what is inside; a signature helps verify integrity and trusted origin; provenance describes how an artifact was built. Small teams can stage these controls without turning Compose into a platform project.
What should come first?
Inventory the images you run, record immutable digests, and define trusted registries and builders. Then decide whether verification belongs in CI, deployment admission, or a manual release check. A signature without a trusted verification policy is documentation, not enforcement.
Where does Cosign fit?
Cosign is a Sigstore project used for signing and verifying OCI artifacts. Docker documents Cosign signatures for Docker Hardened Images; the same distinction applies generally: verify the image digest and the signer identity, not merely a mutable latest tag.
Provenance adds build context. It can help answer which workflow produced an image, but it does not prove that the source or dependencies were safe. Keep vulnerability review, dependency updates, and runtime least privilege alongside it.
For adjacent container controls, see rootless Docker and user namespaces and Docker port exposure.