Docker Sandbox Kit Specification is a specification for describing the runtime environment, capabilities, and authority model of containerized agents and workloads beyond what a Dockerfile can express.
The specification addresses the problem that Dockerfiles describe only the contents of a container image, leaving the runtime environment, network access, credential grants, and external dependencies to be managed separately through docker run flags, compose files, CI configs, and documentation. This fragmentation means authority decisions—what resources an agent can access—remain unversioned and unreviewable. The Kit specification brings these concerns into a single, versioned artifact by defining a descriptor grammar that captures both the content and the authority an agent requires, making those decisions diffable and reviewable as part of the image itself rather than scattered across deployment configurations.
The specification is most relevant for teams deploying agents and autonomous workloads that need explicit, auditable control over what resources and capabilities they can access. It suits projects where authority decisions are material to security and compliance, and where reproducibility of those decisions across different deployment environments matters. The approach is particularly valuable when agent versions introduce new capability requirements—those changes surface as diffs in the Kit descriptor rather than hidden in updated deployment scripts or documentation.
The project maintains a BuildKit frontend for building Kits and conformance suites for validating both published Kits and runtimes claiming to support them. Development activity shows consistent engagement with the specification itself, with updates to the descriptor grammar and the conformance test suites. The project includes tooling across multiple concerns—the grammar definition, OCI artifact handling, and build integration—indicating active work to make the specification practically usable rather than theoretical.
