# Observability Patterns

Use these decisions alongside the linked implementation guides. Application event schemas, billing policies, alert thresholds, and delivery behavior still need to be designed for the application.

| Task | Design decision and documentation |
| --- | --- |
| Usage-based billing | Define the billable event, tenant identity, time window, and accuracy requirements. Start with the maintained [Analytics Engine billing recipe](https://developers.cloudflare.com/analytics/analytics-engine/recipes/usage-based-billing-for-your-saas-product/index.md) and [sampling guidance](https://developers.cloudflare.com/analytics/analytics-engine/sampling/index.md); assess whether sampled estimates satisfy the billing contract. |
| Performance monitoring | Use [built-in metrics](https://developers.cloudflare.com/workers/observability/metrics-and-analytics/index.md) for aggregate health and [traces](https://developers.cloudflare.com/workers/observability/traces/index.md) to investigate dependency latency. Custom measurements need consistent units and aggregation semantics; check [runtime timers](https://developers.cloudflare.com/workers/runtime-apis/performance/index.md) before measuring CPU-only work. |
| Error tracking | Emit structured context without secrets, investigate with [Query Builder](https://developers.cloudflare.com/workers/observability/query-builder/index.md), and choose [Tail Workers](https://developers.cloudflare.com/workers/observability/logs/tail-workers/index.md) if custom alert processing is needed. Define thresholds and duplicate handling for your alert destination. |
| Multi-tenant tracking | Choose the tenant dimension and consistent field positions using [Analytics Engine get started](https://developers.cloudflare.com/analytics/analytics-engine/get-started/index.md) and [sampling guidance](https://developers.cloudflare.com/analytics/analytics-engine/sampling/index.md). Enforce tenant authorization in the application that exposes analytics; a dataset index is not an access-control boundary. |
| Tail Worker filtering | Use the current [Tail handler schema](https://developers.cloudflare.com/workers/runtime-apis/handlers/tail/index.md) for outcomes, exceptions, and timing fields, with [Tail configuration](https://developers.cloudflare.com/workers/observability/logs/tail-workers/index.md) for producer wiring. Define filtering, redaction, and downstream failure handling for the destination. |
| OpenTelemetry export | Prefer the maintained [OTLP export integration](https://developers.cloudflare.com/observability/export/opentelemetry/index.md) for supported destinations. For Honeycomb, follow [Export to Honeycomb](https://developers.cloudflare.com/observability/export/opentelemetry/honeycomb/index.md) instead of synthesizing spans from Tail events. |

Use [Workers Logpush](https://developers.cloudflare.com/workers/observability/logs/logpush/index.md) when the requirement is Workers Trace Event delivery to a supported log destination. Use a Tail Worker when custom processing is required beyond the configured export integration.