Behaviour for metric specification modules consumed by OtelBridge.

A spec module defines metric metadata in plain Telemetry.Metrics terms while leaving OpenTelemetry instrument creation and backend policy to the bridge.

Example

defmodule MyApp.Metrics do
  use OtelBridge.Spec

  @impl OtelBridge.Spec
  def metrics(meta) do
    [
      summary("my_app.request.duration",
        event_name: [:my_app, :request, :stop],
        measurement: :duration,
        unit: {:native, :millisecond},
        tags: [:route],
        tag_values: fn metadata ->
          Map.put(metadata, :route, Keyword.get(meta, :default_route, "unknown"))
        end
      )
    ]
  end
end