BuildKit

BuildKit is Docker’s newer build engine for creating images with better caching, parallelism, and output control. In CI/CD, it also becomes part of the trust chain because build behaviour, provenance, and reproducibility can vary depending on how it is configured and invoked.

Expanded Definition

BuildKit is the build subsystem used with Docker to create container images, but its security relevance goes beyond faster builds and improved layer caching. It changes how build steps are executed, how secrets are passed into the build context, and how provenance data can be attached to the resulting image. That makes it part of the software supply chain, especially when organisations use CI/CD pipelines to produce artefacts that are later deployed into production.

Definitions vary across vendors and toolchains on how much BuildKit itself guarantees versus what must be configured around it. NHI Management Group treats BuildKit as an execution and trust boundary, not just a convenience feature. Its behaviour depends on flags, build drivers, remote builders, and whether organisations explicitly enable provenance, attestations, and reproducible inputs. For governance teams, the key question is not only whether the image was built, but whether the build was observable and defensible.

The most common misapplication is assuming BuildKit automatically makes a build secure, which occurs when teams enable it for performance but leave secrets handling, base image trust, and provenance controls unmanaged.

Examples and Use Cases

Implementing BuildKit rigorously often introduces pipeline complexity, requiring organisations to weigh build speed and observability against tighter configuration discipline and more careful secret handling.

• CI pipelines use BuildKit to speed up repeated image builds through caching, while security teams require pinned base images and deterministic inputs to reduce drift.
• Engineering teams mount secrets during a build so credentials are not baked into the image, aligning with guidance from the Docker BuildKit documentation on ephemeral secret use.
• Release processes generate provenance or attestations so downstream consumers can verify how an artefact was produced, which supports supply chain controls described in the NIST Cybersecurity Framework 2.0.
• Platform teams run remote BuildKit builders in shared infrastructure, then restrict who can invoke them and what data sources they can reach.
• Security reviewers compare image outputs from repeated builds to detect non-reproducible behaviour, unexpected network access, or hidden dependencies introduced during compilation.

Why It Matters for Security Teams

BuildKit matters because the build process can be a point of compromise even when application code looks clean. If an attacker alters the build environment, injects a malicious dependency, or captures secrets exposed during compilation, the resulting image may appear legitimate while carrying embedded risk into production. That is why BuildKit should be treated as part of the broader control environment for software supply chain security, not just as a developer productivity tool.

This is especially relevant for teams using CI/CD to produce container images for identity services, IAM platforms, or agentic AI workloads, where a compromised build can undermine authentication flows, token handling, or model-serving components. Controls around provenance, build isolation, and least-privilege builder access align with the governance intent of the NIST Cybersecurity Framework 2.0, even when organisations implement them through different tooling.

Organisations typically encounter the consequences only after a suspicious image, failed audit, or production incident forces them to reconstruct how the artefact was built, at which point BuildKit becomes operationally unavoidable to address.

Related resources from NHI Mgmt Group

• What is the difference between Docker Secrets and BuildKit secret mounts?
• BuildKit secret mount