The base image is the biggest piece of software most teams never read. Safeguard's Secure Containers page describes a catalogue meant to be smaller and verifiable.
What it is
The page describes hardened base images rebuilt from upstream source in a factory pipeline. Images are distroless style: no shell, package manager or busybox. Debug variants exist for engineering work, not production. Each image has a semver tag and an immutable sha256 digest, and works with any orchestrator or registry.
Images and attestations are signed with Sigstore and recorded in its public transparency log. Each carries an in-toto attestation with SLSA provenance describing the source commit, build platform, dependencies and signer identity, and an SBOM in CycloneDX and SPDX.
How to use it
- Pin by digest, not by tag.
- Verify with cosign before you deploy. Use the identity and issuer the vendor documents.
- Add an admission controller that rejects unsigned images at the cluster boundary. The page names several that work for this.
- Keep the SBOM with the release.
cosign verify --certificate-identity IDENTITY --certificate-oidc-issuer ISSUER IMAGE@sha256:DIGEST
Replace the uppercase words with the values from the image documentation.
What to verify
The page uses labels such as near-zero CVE and quotes patch timings in hours, without measured data. The package and CVE comparison on the page is an illustration. Scan the image yourself.
Quick check
Why pin by digest?
A tag can move. A sha256 digest names exactly one set of bits.
