Closure View¶

The closure view shows a Sankey diagram of a build's (or evaluation's) full dependency closure, sized by uncompressed NAR size. It exists to answer "what is taking up space?" when trimming netboot images, ISOs, or container layers.

Open it from an entry point's metrics page via the View Closure button, which links to the closure of that entry point's most recent build.

Runtime vs build closure¶

The view shows the runtime closure by default - the transitive store-path references (narinfo References:) of the build's outputs, i.e. what the artefact actually needs to run. It is only as complete as the cached outputs. Append ?type=build to the URL to see the build-time closure instead (the full derivation dependency graph); there is no button for this, it is reached by URL only. The header badge shows which closure is displayed.

The dependency graph is a DAG, which has no conserved flow; rendering it as a Sankey directly produces meaningless bar heights and backward links. The view therefore reduces it to a rooted tree (each package keeps a single parent, via breadth-first walk from the roots) and sizes every flow by the package's accumulated closure size - its own NAR size plus everything it pulls in. Flow accumulates from leaf packages on the left into the root on the right, so a bar's height reflects how much that package contributes to the total.

The largest packages render individually; everything outside the top 500 by closure size collapses into a per-parent others bucket attached to its nearest kept ancestor. The header shows the exact total closure size and warns when a very large closure had its node list truncated server-side (the total stays exact regardless). The diagram uses the open-source d3-sankey renderer and shares the dependency graph's controls: scroll to zoom, drag to pan, and the zoom-in / zoom-out / fit-to-screen buttons in the header.

API¶

Both endpoints return per-node sizes plus an exact total_size_bytes, so they are also useful for custom tooling and scripts:

GET /api/v1/builds/{build}/closure          # build-time closure
GET /api/v1/evals/{evaluation}/closure
GET /api/v1/builds/{build}/runtime-closure  # runtime reference closure
GET /api/v1/evals/{evaluation}/runtime-closure

Response (ClosureGraph): roots, total_size_bytes, node_count, edge_count, truncated, nodes (id, name, path, nar_size), and edges (source → target, where target depends on source). Node ids are derivation UUIDs for the build closure and store-path hashes for the runtime closure.