fix: otel metric semantic convs

libs/hooks/open-telemetry/src/lib/conventions.ts

@@ -0,0 +1,16 @@
+// see: https://opentelemetry.io/docs/specs/otel/logs/semantic_conventions/feature-flags/
+export const FEATURE_FLAG = 'feature_flag';
+export const EXCEPTION_ATTR = 'exception'
+
+export const ACTIVE_COUNT_NAME = `${FEATURE_FLAG}.evaluation_active_count`;
+export const REQUESTS_TOTAL_NAME = `${FEATURE_FLAG}.evaluation_requests_total`;
+export const SUCCESS_TOTAL_NAME = `${FEATURE_FLAG}.evaluation_success_total`;
+export const ERROR_TOTAL_NAME = `${FEATURE_FLAG}.evaluation_error_total`;
+
+export type EvaluationAttributes = {[key: `${typeof FEATURE_FLAG}.${string}`]: string | undefined };
+export type ExceptionAttributes = { [EXCEPTION_ATTR]: string };
+
+export const KEY_ATTR: keyof EvaluationAttributes = `${FEATURE_FLAG}.key`;
+export const PROVIDER_NAME_ATTR: keyof EvaluationAttributes = `${FEATURE_FLAG}.provider_name`;
+export const VARIANT_ATTR: keyof EvaluationAttributes = `${FEATURE_FLAG}.variant`;
+export const REASON_ATTR: keyof EvaluationAttributes = `${FEATURE_FLAG}.reason`;

libs/hooks/open-telemetry/src/lib/metrics/metrics-hook.spec.ts

@@ -6,7 +6,7 @@ import {
   MetricReader,
   ScopeMetrics,
 } from '@opentelemetry/sdk-metrics';
-import { ACTIVE_COUNT_NAME, ERROR_TOTAL_NAME, REQUESTS_TOTAL_NAME, SUCCESS_TOTAL_NAME } from '../constants';
+import { ACTIVE_COUNT_NAME, ERROR_TOTAL_NAME, KEY_ATTR, PROVIDER_NAME_ATTR, REASON_ATTR, REQUESTS_TOTAL_NAME, SUCCESS_TOTAL_NAME, VARIANT_ATTR } from '../conventions';
 import { MetricsHook } from './metrics-hook';
 
 // no-op "in-memory" reader
@@ -53,7 +53,7 @@ describe(MetricsHook.name, () => {
           ACTIVE_COUNT_NAME,
           0,
           (point) =>
-            point.value === 1 && point.attributes.key === FLAG_KEY && point.attributes.provider === PROVIDER_NAME
+            point.value === 1 && point.attributes[KEY_ATTR] === FLAG_KEY && point.attributes[PROVIDER_NAME_ATTR] === PROVIDER_NAME
         )
       ).toBeTruthy();
       expect(
@@ -62,7 +62,7 @@ describe(MetricsHook.name, () => {
           REQUESTS_TOTAL_NAME,
           0,
           (point) =>
-            point.value === 1 && point.attributes.key === FLAG_KEY && point.attributes.provider === PROVIDER_NAME
+            point.value === 1 && point.attributes[KEY_ATTR] === FLAG_KEY && point.attributes[PROVIDER_NAME_ATTR] === PROVIDER_NAME
         )
       ).toBeTruthy();
     });
@@ -97,10 +97,10 @@ describe(MetricsHook.name, () => {
             0,
             (point) =>
               point.value === 1 &&
-              point.attributes.key === FLAG_KEY &&
-              point.attributes.provider === PROVIDER_NAME &&
-              point.attributes.variant === VARIANT &&
-              point.attributes.reason === StandardResolutionReasons.STATIC
+              point.attributes[KEY_ATTR] === FLAG_KEY &&
+              point.attributes[PROVIDER_NAME_ATTR] === PROVIDER_NAME &&
+              point.attributes[VARIANT_ATTR] === VARIANT &&
+              point.attributes[REASON_ATTR] === StandardResolutionReasons.STATIC
           )
         ).toBeTruthy();
       });
@@ -130,10 +130,10 @@ describe(MetricsHook.name, () => {
             1,
             (point) =>
               point.value === 1 &&
-              point.attributes.key === FLAG_KEY &&
-              point.attributes.provider === PROVIDER_NAME &&
-              point.attributes.variant === VALUE.toString() &&
-              point.attributes.reason === StandardResolutionReasons.STATIC
+              point.attributes[KEY_ATTR] === FLAG_KEY &&
+              point.attributes[PROVIDER_NAME_ATTR] === PROVIDER_NAME &&
+              point.attributes[VARIANT_ATTR] === VALUE.toString() &&
+              point.attributes[REASON_ATTR] === StandardResolutionReasons.STATIC
           )
         ).toBeTruthy();
       });
@@ -160,7 +160,7 @@ describe(MetricsHook.name, () => {
           ACTIVE_COUNT_NAME,
           1,
           (point) =>
-            point.value === -1 && point.attributes.key === FLAG_KEY && point.attributes.provider === PROVIDER_NAME
+            point.value === -1 && point.attributes[KEY_ATTR] === FLAG_KEY && point.attributes[PROVIDER_NAME_ATTR] === PROVIDER_NAME
         )
       ).toBeTruthy();
     });
@@ -188,7 +188,7 @@ describe(MetricsHook.name, () => {
           ERROR_TOTAL_NAME,
           0,
           (point) =>
-            point.value === 1 && point.attributes.key === FLAG_KEY && point.attributes.provider === PROVIDER_NAME
+            point.value === 1 && point.attributes[KEY_ATTR] === FLAG_KEY && point.attributes[PROVIDER_NAME_ATTR] === PROVIDER_NAME
         )
       ).toBeTruthy();
     });

libs/hooks/open-telemetry/src/lib/metrics/metrics-hook.ts

@@ -7,13 +7,21 @@ import {
   type HookContext,
 } from '@openfeature/js-sdk';
 import { Counter, UpDownCounter, ValueType, metrics } from '@opentelemetry/api';
-import { ACTIVE_COUNT_NAME, ERROR_TOTAL_NAME, REQUESTS_TOTAL_NAME, SUCCESS_TOTAL_NAME } from '../constants';
+import {
+  ACTIVE_COUNT_NAME,
+  EXCEPTION_ATTR,
+  ERROR_TOTAL_NAME,
+  EvaluationAttributes,
+  ExceptionAttributes,
+  KEY_ATTR,
+  PROVIDER_NAME_ATTR,
+  REASON_ATTR,
+  REQUESTS_TOTAL_NAME,
+  SUCCESS_TOTAL_NAME,
+  VARIANT_ATTR
+} from '../conventions';
 
-type EvaluationAttributes = Pick<EvaluationDetails<FlagValue>, 'variant' | 'reason'> & {
-  key: string;
-  provider: string;
-};
-type ErrorEvaluationAttributes = EvaluationAttributes & { exception: string };
+type ErrorEvaluationAttributes = EvaluationAttributes & ExceptionAttributes;
 
 const METER_NAME = 'js.openfeature.dev';
 
@@ -49,35 +57,35 @@ export class MetricsHook implements Hook {
   }
 
   before(hookContext: BeforeHookContext) {
-    const attributes = {
-      key: hookContext.flagKey,
-      provider: hookContext.providerMetadata.name,
+    const attributes: EvaluationAttributes = {
+      [KEY_ATTR]: hookContext.flagKey,
+      [PROVIDER_NAME_ATTR]: hookContext.providerMetadata.name,
     };
     this.evaluationActiveUpDownCounter.add(1, attributes);
     this.evaluationRequestCounter.add(1, attributes);
   }
 
   after(hookContext: Readonly<HookContext<FlagValue>>, evaluationDetails: EvaluationDetails<FlagValue>) {
     this.evaluationSuccessCounter.add(1, {
-      key: hookContext.flagKey,
-      provider: hookContext.providerMetadata.name,
-      variant: evaluationDetails.variant ?? evaluationDetails.value?.toString(),
-      reason: evaluationDetails.reason ?? StandardResolutionReasons.UNKNOWN,
+      [KEY_ATTR]: hookContext.flagKey,
+      [PROVIDER_NAME_ATTR]: hookContext.providerMetadata.name,
+      [VARIANT_ATTR]: evaluationDetails.variant ?? evaluationDetails.value?.toString(),
+      [REASON_ATTR]: evaluationDetails.reason ?? StandardResolutionReasons.UNKNOWN,
     });
   }
 
   error(hookContext: Readonly<HookContext<FlagValue>>, error: unknown) {
     this.evaluationErrorCounter.add(1, {
-      key: hookContext.flagKey,
-      provider: hookContext.providerMetadata.name,
-      exception: (error as Error)?.message || 'Unknown error',
+      [KEY_ATTR]: hookContext.flagKey,
+      [PROVIDER_NAME_ATTR]: hookContext.providerMetadata.name,
+      [EXCEPTION_ATTR]: (error as Error)?.message || 'Unknown error',
     });
   }
 
   finally(hookContext: Readonly<HookContext<FlagValue>>) {
     this.evaluationActiveUpDownCounter.add(-1, {
-      key: hookContext.flagKey,
-      provider: hookContext.providerMetadata.name,
+      [KEY_ATTR]: hookContext.flagKey,
+      [PROVIDER_NAME_ATTR]: hookContext.providerMetadata.name,
     });
   }
 }

libs/hooks/open-telemetry/src/lib/traces/tracing-hook.ts

@@ -1,12 +1,6 @@
 import { Hook, HookContext, EvaluationDetails, FlagValue } from '@openfeature/js-sdk';
 import { trace } from '@opentelemetry/api';
-import { FEATURE_FLAG } from '../constants';
-
-const spanEventProperties = Object.freeze({
-  FLAG_KEY: `${FEATURE_FLAG}.key`,
-  PROVIDER_NAME: `${FEATURE_FLAG}.provider_name`,
-  VARIANT: `${FEATURE_FLAG}.variant`,
-});
+import { FEATURE_FLAG, KEY_ATTR, PROVIDER_NAME_ATTR, VARIANT_ATTR } from '../conventions';
 
 export class TracingHook implements Hook {
   after(hookContext: HookContext, evaluationDetails: EvaluationDetails<FlagValue>) {
@@ -23,9 +17,9 @@ export class TracingHook implements Hook {
       }
 
       currentTrace.addEvent(FEATURE_FLAG, {
-        [spanEventProperties.FLAG_KEY]: hookContext.flagKey,
-        [spanEventProperties.PROVIDER_NAME]: hookContext.providerMetadata.name,
-        [spanEventProperties.VARIANT]: variant,
+        [KEY_ATTR]: hookContext.flagKey,
+        [PROVIDER_NAME_ATTR]: hookContext.providerMetadata.name,
+        [VARIANT_ATTR]: variant,
       });
     }
   }