Internals

Implementation details outside the scheduler and the protocol. The pages are covering Git host events, NAR storage and serving, SQL graph queries and request authentication. Paths are relative to backend/.

flowchart LR
    githost[Git host] -->|webhook| hooks[Git Host Webhooks]
    hooks --> eval[Evaluation]
    worker[Worker] -->|NAR| storage[NAR Storage]
    storage --> serving[Cache Serving]
    serving --> nix[nix clients]
    eval --> dag[(Graph)]
    dag --> queries[Graph Queries]

• Git Host Webhooks

  Hook routes, signature checks and the chain from a push to a queued evaluation.

• NAR Storage

  Object layout, idempotent writes, bucket requirements, closure rows and the deep GC.

• Cache Serving

  Signing, narinfo, pull-through, debug info and the status codes under /cache/.

• Graph Queries

  Recursive walks, the OFFSET 0 fence, indexes, counter updates, metrics and the graph API.

• Authentication

  Sessions, API keys, download tokens and OIDC.

Covered Elsewhere

Topic	Page
Evaluation steps, fetch and walk	Jobs, Eval Worker Setup
Batch import, shared builds	Shared Builds
Queueing, start conditions, failure cascade	Queueing and Counters
Offers, assignment, scoring	Capabilities and Assignment, Scoring
Uploads and downloads	Transfer
Complete closures, cache access	Cache Closure
Worker registration and auth	Connection
Statuses	Evaluations and Builds