# Semantic Conventions for Feature Flags in Logs **Status**: [Experimental][DocumentStatus] This document defines semantic conventions for recording feature flag evaluations as a [log record](https://github.com/open-telemetry/opentelemetry-specification/tree/v1.37.0/specification/logs/data-model.md#log-and-event-record-definition) emitted through the [Logger API](https://github.com/open-telemetry/opentelemetry-specification/tree/v1.37.0/specification/logs/bridge-api.md#emit-a-logrecord). This is useful when a flag is evaluated outside of a transaction context such as when the application loads or on a timer. To record a flag evaluation as a part of a transaction context, consider [recording it as a span event](feature-flags-spans.md). For more information about why it is useful to capture feature flag evaluations, refer to the [motivation](feature-flags-spans.md#motivation) section of the trace semantic convention for feature flag evaluations. - [Recording an Evaluation](#recording-an-evaluation) - [Evaluation event](#evaluation-event) ## Recording an Evaluation Feature flag evaluations SHOULD be recorded as attributes on the [LogRecord](https://github.com/open-telemetry/opentelemetry-specification/tree/v1.37.0/specification/logs/data-model.md#log-and-event-record-definition) passed to the [Logger](https://github.com/open-telemetry/opentelemetry-specification/tree/v1.37.0/specification/logs/bridge-api.md#logger) emit operations. Evaluations MAY be recorded on "logs" or "events" depending on the context. ## Evaluation event The table below indicates which attributes should be added to the [LogRecord](https://github.com/open-telemetry/opentelemetry-specification/tree/v1.37.0/specification/logs/data-model.md#log-and-event-record-definition) and their types. **Status:**  The event name MUST be `feature_flag`. This event describes feature flag evaluation representation on a Log Record. | Attribute | Type | Description | Examples | [Requirement Level](https://opentelemetry.io/docs/specs/semconv/general/attribute-requirement-level/) | Stability | |---|---|---|---|---|---| | [`feature_flag.key`](/docs/attributes-registry/feature-flag.md) | string | The unique identifier of the feature flag. | `logo-color` | `Recommended` |  | | [`feature_flag.provider_name`](/docs/attributes-registry/feature-flag.md) | string | The name of the service provider that performs the flag evaluation. | `Flag Manager` | `Recommended` |  | | [`feature_flag.variant`](/docs/attributes-registry/feature-flag.md) | string | SHOULD be a semantic identifier for a value. If one is unavailable, a stringified version of the value can be used. [1] | `red`; `true`; `on` | `Recommended` |  | **[1]:** A semantic identifier, commonly referred to as a variant, provides a means for referring to a value without including the value itself. This can provide additional context for understanding the meaning behind a value. For example, the variant `red` maybe be used for the value `#c05543`. A stringified version of the value can be used in situations where a semantic identifier is unavailable. String representation of the value should be determined by the implementer. [DocumentStatus]: https://opentelemetry.io/docs/specs/otel/document-status