Verify release manifests with Cosign bundles before deployment
A release manifest is often the small file that connects an approved build to a deployment. It might list image digests, package hashes, chart versions, or a generated SBOM. If an automation job fetches that file and treats it as trusted without checking its signature, changing one line can redirect a deployment to a different artifact.
This guide builds a small verification boundary around a detached release manifest using Cosign 3.1.3 and a self-managed signing key. The result is a script that accepts only a manifest that matches its Cosign bundle and configured public key, and exits nonzero before a deployment step can read it. A successful run prints Verified OK; a manifest changed after signing is rejected with an invalid-signature error.