Telemetry

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Aurora Meter emits :telemetry events you can attach to for metrics and logs.

EventMeasurementsMetadata
[:aurora_meter, :track]%{count}%{tenant_key, feature}
[:aurora_meter, :reserve]%{qty}%{tenant_key, feature, result} — result is :ok, :limit_exceeded or :not_entitled
[:aurora_meter, :flush]%{count, delta_sum}%{}
[:aurora_meter, :flush, :error]%{count}%{error} — the database write failed; the deltas stay pending
[:aurora_meter, :broadcast]%{count, deltas}%{}
[:aurora_meter, :cluster, :apply]%{count}%{kind, origin} — deltas or totals applied from another node
[:aurora_meter, :credits, kind]%{amount, balance_after, available_after}%{tenant_key, reference, category, duplicate, overrun} — one per committed ledger entry; kind is :grant, :hold, :settle, :release, :debit or :expire. duplicate: true marks an idempotent grant replay (amount 0), overrun: true a settlement above its hold
[:aurora_meter, :credits, :low_balance]%{available, threshold}%{tenant_key} — the available balance crossed below the threshold (once per crossing)

Example — count tracked usage with Telemetry.Metrics:

def metrics do
  [
    Telemetry.Metrics.sum("aurora_meter.track.count", tags: [:feature]),
    Telemetry.Metrics.summary("aurora_meter.flush.count"),
    Telemetry.Metrics.sum("aurora_meter.credits.settle.amount", tags: [:tenant_key]),
    Telemetry.Metrics.counter("aurora_meter.credits.low_balance.available")
  ]
end

Attach a handler directly:

:telemetry.attach(
  "log-aurora-flush",
  [:aurora_meter, :flush],
  fn _event, %{count: n}, _meta, _cfg -> Logger.info("flushed #{n} counters") end,
  nil
)