Add value_type to feature flag event

.chloggen/feature-flag-eval-value-type.yaml

@@ -0,0 +1,22 @@
+# Use this changelog template to create an entry for release notes.
+#
+# If your change doesn't affect end users you should instead start
+# your pull request title with [chore] or use the "Skip Changelog" label.
+
+# One of 'breaking', 'deprecation', 'new_component', 'enhancement', 'bug_fix'
+change_type: enhancement
+
+# The name of the area of concern in the attributes-registry, (e.g. http, cloud, db)
+component: feature_flag
+
+# A brief description of the change. Surround your text with quotes ("") if it needs to start with a backtick (`).
+note: Add `feature_flag.evaluation.value_type` event attribute.
+
+# Mandatory: One or more tracking issues related to the change. You can use the PR number here if no issue exists.
+# The values here must be integers.
+issues: [4349]
+
+# (Optional) One or more lines of additional information to render under the primary note.
+# These lines will be padded with 2 spaces and then inserted directly into the document.
+# Use pipe (|) for multiline entries.
+subtext:

docs/attributes-registry/feature-flag.md

@@ -15,6 +15,7 @@ This document defines attributes for Feature Flags.
 | <a id="feature-flag-context-id" href="#feature-flag-context-id">`feature_flag.context.id`</a> | string | The unique identifier for the flag evaluation context. For example, the targeting key. | `5157782b-2203-4c80-a857-dbbd5e7761db` | ![Experimental](https://img.shields.io/badge/-experimental-blue) |
 | <a id="feature-flag-evaluation-error-message" href="#feature-flag-evaluation-error-message">`feature_flag.evaluation.error.message`</a> | string | A message explaining the nature of an error occurring during flag evaluation. | `Flag `header-color` expected type `string` but found type `number`` | ![Experimental](https://img.shields.io/badge/-experimental-blue) |
 | <a id="feature-flag-evaluation-reason" href="#feature-flag-evaluation-reason">`feature_flag.evaluation.reason`</a> | string | The reason code which shows how a feature flag value was determined. | `static`; `targeting_match`; `error`; `default` | ![Experimental](https://img.shields.io/badge/-experimental-blue) |
+| <a id="feature-flag-evaluation-value-type" href="#feature-flag-evaluation-value-type">`feature_flag.evaluation.value_type`</a> | string | Indicates the type of the `feature_flag.evaluation` event body field `value`. | `string`; `boolean` | ![Experimental](https://img.shields.io/badge/-experimental-blue) |
 | <a id="feature-flag-key" href="#feature-flag-key">`feature_flag.key`</a> | string | The lookup key of the feature flag. | `logo-color` | ![Experimental](https://img.shields.io/badge/-experimental-blue) |
 | <a id="feature-flag-provider-name" href="#feature-flag-provider-name">`feature_flag.provider_name`</a> | string | Identifies the feature flag provider. | `Flag Manager` | ![Experimental](https://img.shields.io/badge/-experimental-blue) |
 | <a id="feature-flag-set-id" href="#feature-flag-set-id">`feature_flag.set.id`</a> | string | The identifier of the [flag set](https://openfeature.dev/specification/glossary/#flag-set) to which the feature flag belongs. | `proj-1`; `ab98sgs`; `service1/dev` | ![Experimental](https://img.shields.io/badge/-experimental-blue) |
@@ -41,3 +42,19 @@ For example, the variant `red` maybe be used for the value `#c05543`.
 | `static` | The resolved value is static (no dynamic evaluation). | ![Experimental](https://img.shields.io/badge/-experimental-blue) |
 | `targeting_match` | The resolved value was the result of a dynamic evaluation, such as a rule or specific user-targeting. | ![Experimental](https://img.shields.io/badge/-experimental-blue) |
 | `unknown` | The reason for the resolved value could not be determined. | ![Experimental](https://img.shields.io/badge/-experimental-blue) |
+
+---
+
+`feature_flag.evaluation.value_type` has the following list of well-known values. If one of them applies, then the respective value MUST be used; otherwise, a custom value MAY be used.
+
+| Value  | Description | Stability |
+|---|---|---|
+| `array` | This indicates the type of `feature_flag.evaluation` event body field `value` is array. | ![Experimental](https://img.shields.io/badge/-experimental-blue) |
+| `boolean` | This indicates the type of `feature_flag.evaluation` event body field `value` is boolean. | ![Experimental](https://img.shields.io/badge/-experimental-blue) |
+| `byte_array` | This indicates the type of `feature_flag.evaluation` event body field `value` is byte array. | ![Experimental](https://img.shields.io/badge/-experimental-blue) |
+| `float` | This indicates the type of `feature_flag.evaluation` event body field `value` is double precision floating point (IEEE 754-1985). | ![Experimental](https://img.shields.io/badge/-experimental-blue) |
+| `int` | This indicates the type of `feature_flag.evaluation` event body field `value` is 64-bit integer. | ![Experimental](https://img.shields.io/badge/-experimental-blue) |
+| `map` | This indicates the type of `feature_flag.evaluation` event body field `value` is map. | ![Experimental](https://img.shields.io/badge/-experimental-blue) |
+| `null` | This indicates the type of `feature_flag.evaluation` event body field `value` is null. | ![Experimental](https://img.shields.io/badge/-experimental-blue) |
+| `string` | This indicates the type of `feature_flag.evaluation` event body field `value` is string. | ![Experimental](https://img.shields.io/badge/-experimental-blue) |
+| `unknown` | This indicates the type of `feature_flag.evaluation` event body field `value` is unknown. | ![Experimental](https://img.shields.io/badge/-experimental-blue) |

docs/feature-flags/feature-flags-logs.md

@@ -60,9 +60,10 @@ A `feature_flag.evaluation` event SHOULD be emitted whenever a feature flag valu
 |---|---|---|---|---|---|
 | [`feature_flag.key`](/docs/attributes-registry/feature-flag.md) | string | The lookup key of the feature flag. | `logo-color` | `Required` | ![Experimental](https://img.shields.io/badge/-experimental-blue) |
 | [`error.type`](/docs/attributes-registry/error.md) | string | Describes a class of error the operation ended with. [1] | `provider_not_ready`; `targeting_key_missing`; `provider_fatal`; `general` | `Conditionally Required` [2] | ![Stable](https://img.shields.io/badge/-stable-lightgreen) |
-| [`feature_flag.variant`](/docs/attributes-registry/feature-flag.md) | string | A semantic identifier for an evaluated flag value. [3] | `red`; `true`; `on` | `Conditionally Required` [4] | ![Experimental](https://img.shields.io/badge/-experimental-blue) |
+| [`feature_flag.evaluation.value_type`](/docs/attributes-registry/feature-flag.md) | string | Indicates the type of the `feature_flag.evaluation` event body field `value`. | `string`; `boolean` | `Conditionally Required` [3] | ![Experimental](https://img.shields.io/badge/-experimental-blue) |
+| [`feature_flag.variant`](/docs/attributes-registry/feature-flag.md) | string | A semantic identifier for an evaluated flag value. [4] | `red`; `true`; `on` | `Conditionally Required` [5] | ![Experimental](https://img.shields.io/badge/-experimental-blue) |
 | [`feature_flag.context.id`](/docs/attributes-registry/feature-flag.md) | string | The unique identifier for the flag evaluation context. For example, the targeting key. | `5157782b-2203-4c80-a857-dbbd5e7761db` | `Recommended` | ![Experimental](https://img.shields.io/badge/-experimental-blue) |
-| [`feature_flag.evaluation.error.message`](/docs/attributes-registry/feature-flag.md) | string | A message explaining the nature of an error occurring during flag evaluation. | `Flag `header-color` expected type `string` but found type `number`` | `Recommended` [5] | ![Experimental](https://img.shields.io/badge/-experimental-blue) |
+| [`feature_flag.evaluation.error.message`](/docs/attributes-registry/feature-flag.md) | string | A message explaining the nature of an error occurring during flag evaluation. | `Flag `header-color` expected type `string` but found type `number`` | `Recommended` [6] | ![Experimental](https://img.shields.io/badge/-experimental-blue) |
 | [`feature_flag.evaluation.reason`](/docs/attributes-registry/feature-flag.md) | string | The reason code which shows how a feature flag value was determined. | `static`; `targeting_match`; `error`; `default` | `Recommended` | ![Experimental](https://img.shields.io/badge/-experimental-blue) |
 | [`feature_flag.provider_name`](/docs/attributes-registry/feature-flag.md) | string | Identifies the feature flag provider. | `Flag Manager` | `Recommended` | ![Experimental](https://img.shields.io/badge/-experimental-blue) |
 | [`feature_flag.set.id`](/docs/attributes-registry/feature-flag.md) | string | The identifier of the [flag set](https://openfeature.dev/specification/glossary/#flag-set) to which the feature flag belongs. | `proj-1`; `ab98sgs`; `service1/dev` | `Recommended` | ![Experimental](https://img.shields.io/badge/-experimental-blue) |
@@ -83,14 +84,16 @@ A `feature_flag.evaluation` event SHOULD be emitted whenever a feature flag valu
 
 **[2] `error.type`:** If and only if an error occurred during flag evaluation.
 
-**[3] `feature_flag.variant`:** A semantic identifier, commonly referred to as a variant, provides a means
+**[3] `feature_flag.evaluation.value_type`:** If and only if `value` field is supplied in the event body
+
+**[4] `feature_flag.variant`:** 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`.
 
-**[4] `feature_flag.variant`:** If feature flag provider supplies a variant or equivalent concept.
+**[5] `feature_flag.variant`:** If feature flag provider supplies a variant or equivalent concept.
 
-**[5] `feature_flag.evaluation.error.message`:** If and only if an error occurred. It's NOT RECOMMENDED to duplicate the value of `error.type` in `feature_flag.evaluation.error.message`.
+**[6] `feature_flag.evaluation.error.message`:** If and only if an error occurred. It's NOT RECOMMENDED to duplicate the value of `error.type` in `feature_flag.evaluation.error.message`.
 
 ---
 
@@ -116,6 +119,22 @@ For example, the variant `red` maybe be used for the value `#c05543`.
 | `targeting_match` | The resolved value was the result of a dynamic evaluation, such as a rule or specific user-targeting. | ![Experimental](https://img.shields.io/badge/-experimental-blue) |
 | `unknown` | The reason for the resolved value could not be determined. | ![Experimental](https://img.shields.io/badge/-experimental-blue) |
 
+---
+
+`feature_flag.evaluation.value_type` has the following list of well-known values. If one of them applies, then the respective value MUST be used; otherwise, a custom value MAY be used.
+
+| Value  | Description | Stability |
+|---|---|---|
+| `array` | This indicates the type of `feature_flag.evaluation` event body field `value` is array. | ![Experimental](https://img.shields.io/badge/-experimental-blue) |
+| `boolean` | This indicates the type of `feature_flag.evaluation` event body field `value` is boolean. | ![Experimental](https://img.shields.io/badge/-experimental-blue) |
+| `byte_array` | This indicates the type of `feature_flag.evaluation` event body field `value` is byte array. | ![Experimental](https://img.shields.io/badge/-experimental-blue) |
+| `float` | This indicates the type of `feature_flag.evaluation` event body field `value` is double precision floating point (IEEE 754-1985). | ![Experimental](https://img.shields.io/badge/-experimental-blue) |
+| `int` | This indicates the type of `feature_flag.evaluation` event body field `value` is 64-bit integer. | ![Experimental](https://img.shields.io/badge/-experimental-blue) |
+| `map` | This indicates the type of `feature_flag.evaluation` event body field `value` is map. | ![Experimental](https://img.shields.io/badge/-experimental-blue) |
+| `null` | This indicates the type of `feature_flag.evaluation` event body field `value` is null. | ![Experimental](https://img.shields.io/badge/-experimental-blue) |
+| `string` | This indicates the type of `feature_flag.evaluation` event body field `value` is string. | ![Experimental](https://img.shields.io/badge/-experimental-blue) |
+| `unknown` | This indicates the type of `feature_flag.evaluation` event body field `value` is unknown. | ![Experimental](https://img.shields.io/badge/-experimental-blue) |
+
 **Body fields:**
 
 | Body Field  | Type | Description  | Examples  | [Requirement Level](https://opentelemetry.io/docs/specs/semconv/general/attribute-requirement-level/) | Stability |

model/feature-flags/logs.yaml

@@ -49,6 +49,9 @@ groups:
       - ref: feature_flag.evaluation.error.message
         requirement_level:
           recommended: If and only if an error occurred. It's NOT RECOMMENDED to duplicate the value of `error.type` in `feature_flag.evaluation.error.message`.
+      - ref: feature_flag.evaluation.value_type
+        requirement_level:
+          conditionally_required: If and only if `value` field is supplied in the event body
     body:
       id: feature_flag.evaluation
       type: map

model/feature-flags/registry.yaml

@@ -93,3 +93,45 @@ groups:
         stability: experimental
         examples: ["Flag `header-color` expected type `string` but found type `number`"]
         brief: A message explaining the nature of an error occurring during flag evaluation.
+      - id: feature_flag.evaluation.value_type
+        type:
+          members:
+            - id: string
+              value: "string"
+              brief: This indicates the type of `feature_flag.evaluation` event body field `value` is string.
+              stability: experimental
+            - id: boolean
+              value: "boolean"
+              brief: This indicates the type of `feature_flag.evaluation` event body field `value` is boolean.
+              stability: experimental
+            - id: int
+              value: "int"
+              brief: This indicates the type of `feature_flag.evaluation` event body field `value` is 64-bit integer.
+              stability: experimental
+            - id: float
+              value: "float"
+              brief: This indicates the type of `feature_flag.evaluation` event body field `value` is double precision floating point (IEEE 754-1985).
+              stability: experimental
+            - id: byte_array
+              value: "byte_array"
+              brief: This indicates the type of `feature_flag.evaluation` event body field `value` is byte array.
+              stability: experimental
+            - id: array
+              value: "array"
+              brief: This indicates the type of `feature_flag.evaluation` event body field `value` is array.
+              stability: experimental
+            - id: map
+              value: "map"
+              brief: This indicates the type of `feature_flag.evaluation` event body field `value` is map.
+              stability: experimental
+            - id: "null"
+              value: "null"
+              brief: This indicates the type of `feature_flag.evaluation` event body field `value` is null.
+              stability: experimental
+            - id: unknown
+              value: "unknown"
+              brief: This indicates the type of `feature_flag.evaluation` event body field `value` is unknown.
+              stability: experimental
+        stability: experimental
+        examples: ["string", "boolean"]
+        brief: Indicates the type of the `feature_flag.evaluation` event body field `value`.