Parapet + Accrue

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Accrue is a billing and subscription library. When you attach the Accrue integration, Parapet translates Accrue checkout and webhook telemetry into billing journey metrics you can use as the foundation for a custom SLO.

Prerequisites

  • accrue installed in your host app (optional dep — if it is absent, Accrue never emits the telemetry events the adapter listens for, so the attached handlers stay dormant and harmless; Parapet does not probe for the accrue library itself)
  • Parapet installed and configured (mix parapet.install)

What it unlocks

Accrue billing events become Parapet journey metrics:

  • parapet_journey_billing_checkout_count — counted per outcome and plan tags
  • parapet_journey_billing_webhook_duration — distribution per outcome and event_type tags

There is no pre-built SLO provider for Accrue billing journeys. These metrics are the foundation for a custom slice you author yourself. See SLO authoring guide for the journey-slicing decision tree and the exact SliceSpec shape.

Activation

Add the adapter when you start your supervision tree, typically in application.ex:

Parapet.attach(adapters: [:accrue])

This attaches telemetry handlers for [:accrue, :billing, :processed], [:accrue, :billing, :failed], [:accrue, :billing, :checkout, :stop], [:accrue, :billing, :checkout, :exception], [:accrue, :billing, :webhook, :stop], and [:accrue, :billing, :webhook, :exception].

Config keys

The Accrue integration has no Parapet-level config keys. It reads standard Accrue telemetry events and re-emits them as Parapet journey events without additional configuration.

Troubleshooting

Metrics are not appearing in Prometheus

Confirm two things: (1) Parapet.attach(adapters: [:accrue]) was called before the first Accrue event fired, and (2) your Telemetry.Metrics reporter includes the metrics from Parapet.Metrics.Accrue.metrics(). Without the reporter wiring, the counters and distributions are defined but never scraped.

Checkout events arrive but no billing metrics appear

The checkout handler listens on [:accrue, :billing, :checkout, :stop] and [:accrue, :billing, :checkout, :exception]. If Accrue emits events under a different name or version, the handler is silently skipped. Check Accrue telemetry docs to confirm the event name matches.

I want a burn-rate alert on the checkout success rate

Accrue metrics are the raw ingredient, not a pre-wired alert. You need to define a Parapet.SLO.Provider module with a SliceSpec that references parapet_journey_billing_checkout_count as its source metric, then register it in config :parapet, providers: [...]. The SLO authoring guide walks through the full process.