Understanding SBOM
A Software Bill of Materials (SBOM) is a comprehensive inventory of components, libraries, and dependencies that make up a software artifact such as a container image, application, or binary. Just like a product label lists ingredients, an SBOM allows organizations to identify what their software is composed of.
In Kubernetes environments, SBOMs play a foundational role in supply chain security, helping teams verify the integrity of workloads and trace vulnerabilities to specific packages.
Why SBOMs Matter
SBOMs help improve software transparency and security. They are essential for the following reasons:
-
Vulnerability identification
SBOMs make it possible to scan known packages for vulnerabilities using tools like Grype or Trivy. -
Incident response
In the event of an exploit disclosure (such as Log4Shell), SBOMs help determine which workloads are affected. -
License compliance
Teams can track open source licenses and ensure legal compliance in production software. -
Provenance and trust
SBOMs support attestations and digital signatures that confirm the origin and integrity of a component.
SBOM Generation in Kubernetes Workflows
SBOMs are typically generated during the CI/CD build phase and bundled with container images. These SBOMs can be stored as separate files, pushed to registries, or embedded as image layers.
Tools that generate SBOMs include:
- Syft – Generates SBOMs in formats like SPDX, CycloneDX, and Syft-native. Supports a wide range of ecosystems.
- Trivy – Generates SBOMs alongside vulnerability scans using SPDX or CycloneDX.
- Docker BuildKit – Supports SBOM generation via the
buildxCLI with native SBOM output. - Podman – Supports SBOM generation using
podman image generate sbom.
SBOM Formats
Common SBOM formats used in Kubernetes and cloud-native tooling:
- SPDX – A widely adopted, open standard for sharing SBOMs across vendors.
- CycloneDX – Designed for modern DevSecOps and supports package integrity, dependency graphs, and attestations.
- Syft JSON – A tool-specific format that is easily parsed and integrated into automation pipelines.
SBOM Validation and Use
Once generated, SBOMs can be:
- Stored alongside container images
- Scanned for vulnerabilities using tools like Grype or Trivy
- Signed using tools like Cosign
- Embedded in OCI registries or referenced through attestations
Some Kubernetes admission control solutions can also validate SBOM presence or scan results as part of deployment policy enforcement.
Related Tools
Refer to the following tools for generating, analyzing, and verifying SBOMs:
Conclusion
SBOMs are a critical component of Kubernetes supply chain security. They provide the transparency required to assess risk, respond to vulnerabilities, and validate compliance. By integrating SBOM generation and validation into CI/CD and runtime workflows, organizations can strengthen their defenses against emerging threats and improve overall visibility into their software systems.