Telemetry.Metrics definitions for every core event worth a series.

This module exists only when the optional telemetry_metrics dependency is installed. Without it AuroraMeter.Telemetry and every event still work; this module is simply not defined, and nothing in the library references it.

Use it instead of writing the list yourself

defmodule MyApp.Telemetry do
  def metrics do
    AuroraMeter.Telemetry.Metrics.metrics() ++ my_own_metrics()
  end
end

Every tag here is on AuroraMeter.Telemetry.tag_allow_list/0 and every value set behind one is bounded. Where an event's natural metadata name is not an allow-listed name, or where its value is not bounded, the preset maps it with :tag_values rather than tagging on it raw. The clearest case is [:aurora_meter, :credits, :hold_reconciliation], whose decision is {:settle, amount} for a settlement: tagging on that metadata key directly gives one time series per distinct amount of money, which is unbounded. The preset maps it to kind: :settle.

Cost

metrics/1 is pure: it builds structs and reads configuration. Attaching them is the host's reporter's job, and the reporter's handlers run in the process that emitted the event. The gauges are emitted by AuroraMeter.Store and AuroraMeter.Cluster, so a slow handler on one of them delays flush batch snapshots.

Options

• :feature_label - tag metering metrics on :feature. Defaults to AuroraMeter.Config.metrics_feature_label?/0 (false). One series per feature per metric: cheap for ten features, not for ten thousand.
• :include - which groups to return, any of [:metering, :quotas, :flush, :cluster, :events, :credits, :workers]. Defaults to all of them.

The metric name prefix is fixed at aurora_meter. A host that needs another maps the list itself; making it an option would let two hosts disagree about what a documented metric is called.