A18 · Model Downloader / Artifact Distribution A18 · 模型分发器 / 制品分发系统
Verified source经核实出处
Prompt: "Design a system that distributes model artifacts…integrity validation…rollout to thousands of hosts…rollback…auditability" — PracHub, Onsite 2026-02. Credibility B.
Architecture (control plane + host agent)架构（控制面 + 主机 agent）
flowchart LR REG[(Model Registry)] --> CDN[Artifact Storage / CDN] REG --> CTRL[Rollout Controller] CTRL --> AG[Host Agent] AG --> CDN AG --> RUN[Inference Runtime] AG --> OBS[Report Status] OBS --> CTRL
Correctness invariants正确性不变量
- Manifest = {version, deps, checksum, signature}. Verified before activation.Manifest = {版本、依赖、checksum、签名}。激活前验证。
- Atomic switch: download to staging dir; validate; flip symlink; old kept for rollback.原子切换：下载到暂存目录；校验；切 symlink；旧版本保留用于回滚。
- Rollback: keep last N versions; auto-rollback on agent-reported health failure.回滚：保留最近 N 版本；agent 上报失败时自动回滚。
- Rate control: stage by AZ / batch; prevent thundering-herd download.限速：按 AZ / 批次分发；防止惊群下载。
Observability可观测性
- Per-host status + version lag histogram.按主机状态 + 版本滞后直方图。
- SLI: rollout duration p95, failed-host rate, rollback rate.SLI：rollout 时长 p95、失败主机率、回滚率。