nordisk/holger

.nornir/assets/metrics-flow.svg

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  <text x="20" y="26" class="lbl" font-size="15" font-weight="700">Prometheus /metrics — bump at the call sites, render on scrape</text>

  <!-- The bump sites -->
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  <text x="120" y="76" class="lbl" text-anchor="middle">HTTP door: get/put/delete</text>
  <text x="120" y="91" class="sub" text-anchor="middle">record_request(verb, status, bytes)</text>
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  <text x="120" y="132" class="lbl" text-anchor="middle">/-/search · /-/sbom doors</text>
  <text x="120" y="147" class="sub" text-anchor="middle">record_request(Search|Sbom, …)</text>
  <rect class="surface" x="20" y="168" width="200" height="42" rx="8"/>
  <text x="120" y="188" class="lbl" text-anchor="middle">retention executor</text>
  <text x="120" y="203" class="sub" text-anchor="middle">record_retention_run()</text>

  <!-- The global registry -->
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  <text x="385" y="122" class="lbl" text-anchor="middle" font-weight="700">metrics::global()</text>
  <text x="385" y="142" class="sub" text-anchor="middle">OnceLock&lt;Metrics&gt;</text>
  <text x="385" y="159" class="sub" text-anchor="middle">AtomicU64 counters:</text>
  <text x="385" y="175" class="sub" text-anchor="middle">requests{verb} · bytes</text>
  <text x="385" y="191" class="sub" text-anchor="middle">errors · retention_runs</text>
  <text x="385" y="207" class="sub" text-anchor="middle">(lock-free, relaxed)</text>

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  <!-- The scrape door -->
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  <text x="620" y="122" class="lbl" text-anchor="middle" font-weight="700">GET /metrics</text>
  <text x="620" y="142" class="sub" text-anchor="middle">render_prometheus(</text>
  <text x="620" y="158" class="sub" text-anchor="middle">repo_counts)</text>
  <text x="620" y="178" class="sub" text-anchor="middle">snapshot atomics +</text>
  <text x="620" y="194" class="sub" text-anchor="middle">list() each backend</text>
  <text x="620" y="210" class="sub" text-anchor="middle">(spawn_blocking)</text>
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  <!-- Backends for the gauge -->
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  <text x="620" y="270" class="lbl" text-anchor="middle">every configured backend</text>
  <text x="620" y="288" class="sub" text-anchor="middle">list() → artifact count</text>
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  <text x="790" y="122" class="lbl" text-anchor="middle" font-weight="700">text 0.0.4</text>
  <text x="790" y="146" class="sub" text-anchor="middle">counters</text>
  <text x="790" y="164" class="sub" text-anchor="middle">+ gauges</text>
  <text x="790" y="188" class="sub" text-anchor="middle">Prometheus</text>
  <text x="790" y="204" class="sub" text-anchor="middle">scrapes it</text>
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  <text x="20" y="352" class="sub">Read-only, unauthenticated, unaudited — exposes only aggregate counters, never artifact bytes. No hot-path cost beyond a relaxed atomic add.</text>
  <text x="20" y="374" class="sub">The per-repo artifact gauge is the one scrape-time I/O (bounded list, off the reactor); an errored backend reports 0, never sinks the scrape.</text>
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