Cosign — sign images, verify at admit/deploy

sigstore/cosign supply-chain hygiene: sign at build, verify at admit/deploy. No bypass or attack content.

Supply-chain hygiene only. Cosign (Sigstore) signs and verifies container images (and related artifacts). The MSP-ready pattern: sign at build with keys or keyless OIDC flows your security team approves; verify at admit/deploy via admission policy or deploy gate so unsigned or untrusted digests never reach managed clusters.

Keep provenance (e.g. attestations) beside signatures when your customers require it. Rotate keys, restrict who can push signed tags, and fail closed when verification fails. This draft does not cover bypasses, key theft, or attack chains — only the verify-before-run control.

Pair with image scanning (e.g. Trivy) so signed ≠ automatically safe: signature proves provenance of a digest; scanners still judge known vulns in that digest.

FAQ

Where should verification happen?

At cluster admission or deploy gates — fail closed if the digest lacks an approved signature/identity.

Does signing replace vulnerability scanning?

No. Signing asserts provenance of a digest; scanners still assess known CVEs in that digest.

Sources

Draft only — do not publish without editorial review.