feat: lifecycle stage entered counter (#7449)

src/lib/features/feature-lifecycle/fake-feature-lifecycle-store.ts

@@ -2,6 +2,7 @@ import type {
     FeatureLifecycleStage,
     IFeatureLifecycleStore,
     FeatureLifecycleView,
+    NewStage,
 } from './feature-lifecycle-store-type';
 
 export class FakeFeatureLifecycleStore implements IFeatureLifecycleStore {
@@ -9,20 +10,31 @@ export class FakeFeatureLifecycleStore implements IFeatureLifecycleStore {
 
     async insert(
         featureLifecycleStages: FeatureLifecycleStage[],
-    ): Promise<void> {
-        await Promise.all(
-            featureLifecycleStages.map((stage) => this.insertOne(stage)),
+    ): Promise<NewStage[]> {
+        const results = await Promise.all(
+            featureLifecycleStages.map(async (stage) => {
+                const success = await this.insertOne(stage);
+                if (success) {
+                    return {
+                        feature: stage.feature,
+                        stage: stage.stage,
+                    };
+                }
+                return null;
+            }),
         );
+        return results.filter((result) => result !== null) as NewStage[];
     }
 
     async backfill() {}
 
     private async insertOne(
         featureLifecycleStage: FeatureLifecycleStage,
-    ): Promise<void> {
+    ): Promise<boolean> {
         if (await this.stageExists(featureLifecycleStage)) {
-            return;
+            return false;
         }
+        const newStages: NewStage[] = [];
         const existingStages = await this.get(featureLifecycleStage.feature);
         this.lifecycles[featureLifecycleStage.feature] = [
             ...existingStages,
@@ -34,6 +46,7 @@ export class FakeFeatureLifecycleStore implements IFeatureLifecycleStore {
                 enteredStageAt: new Date(),
             },
         ];
+        return true;
     }
 
     async get(feature: string): Promise<FeatureLifecycleView> {

src/lib/features/feature-lifecycle/feature-lifecycle-service.test.ts

@@ -10,8 +10,8 @@ import {
 } from '../../types';
 import { createFakeFeatureLifecycleService } from './createFeatureLifecycle';
 import EventEmitter from 'events';
-import { STAGE_ENTERED } from './feature-lifecycle-service';
 import noLoggerProvider from '../../../test/fixtures/no-logger';
+import { STAGE_ENTERED } from '../../metric-events';
 
 test('can insert and read lifecycle stages', async () => {
     const eventBus = new EventEmitter();
@@ -42,7 +42,7 @@ test('can insert and read lifecycle stages', async () => {
     }
     function reachedStage(feature: string, name: StageName) {
         return new Promise((resolve) =>
-            featureLifecycleService.on(STAGE_ENTERED, (event) => {
+            eventBus.on(STAGE_ENTERED, (event) => {
                 if (event.stage === name && event.feature === feature)
                     resolve(name);
             }),

src/lib/features/feature-lifecycle/feature-lifecycle-service.ts

@@ -15,17 +15,17 @@ import {
 import type {
     FeatureLifecycleView,
     IFeatureLifecycleStore,
+    NewStage,
 } from './feature-lifecycle-store-type';
-import EventEmitter from 'events';
+import type EventEmitter from 'events';
 import type { Logger } from '../../logger';
 import type EventService from '../events/event-service';
 import type { FeatureLifecycleCompletedSchema } from '../../openapi';
 import type { IClientMetricsEnv } from '../metrics/client-metrics/client-metrics-store-v2-type';
 import groupBy from 'lodash.groupby';
+import { STAGE_ENTERED } from '../../metric-events';
 
-export const STAGE_ENTERED = 'STAGE_ENTERED';
-
-export class FeatureLifecycleService extends EventEmitter {
+export class FeatureLifecycleService {
     private eventStore: IEventStore;
 
     private featureLifecycleStore: IFeatureLifecycleStore;
@@ -65,7 +65,6 @@ export class FeatureLifecycleService extends EventEmitter {
             getLogger,
         }: Pick<IUnleashConfig, 'flagResolver' | 'eventBus' | 'getLogger'>,
     ) {
-        super();
         this.eventStore = eventStore;
         this.featureLifecycleStore = featureLifecycleStore;
         this.environmentStore = environmentStore;
@@ -128,22 +127,26 @@ export class FeatureLifecycleService extends EventEmitter {
     }
 
     private async featureInitialized(feature: string) {
-        await this.featureLifecycleStore.insert([
+        const result = await this.featureLifecycleStore.insert([
             { feature, stage: 'initial' },
         ]);
-        this.emit(STAGE_ENTERED, { stage: 'initial', feature });
+        this.recordStagesEntered(result);
     }
 
     private async stageReceivedMetrics(
         features: string[],
         stage: 'live' | 'pre-live',
     ) {
-        await this.featureLifecycleStore.insert(
+        const newlyEnteredStages = await this.featureLifecycleStore.insert(
             features.map((feature) => ({ feature, stage })),
         );
-        features.forEach((feature) =>
-            this.emit(STAGE_ENTERED, { stage, feature }),
-        );
+        this.recordStagesEntered(newlyEnteredStages);
+    }
+
+    private recordStagesEntered(newlyEnteredStages: NewStage[]) {
+        newlyEnteredStages.forEach(({ stage, feature }) => {
+            this.eventBus.emit(STAGE_ENTERED, { stage, feature });
+        });
     }
 
     private async featuresReceivedMetrics(
@@ -182,7 +185,7 @@ export class FeatureLifecycleService extends EventEmitter {
         status: FeatureLifecycleCompletedSchema,
         auditUser: IAuditUser,
     ) {
-        await this.featureLifecycleStore.insert([
+        const result = await this.featureLifecycleStore.insert([
             {
                 feature,
                 stage: 'completed',
@@ -190,6 +193,7 @@ export class FeatureLifecycleService extends EventEmitter {
                 statusValue: status.statusValue,
             },
         ]);
+        this.recordStagesEntered(result);
         await this.eventService.storeEvent(
             new FeatureCompletedEvent({
                 project: projectId,
@@ -219,10 +223,10 @@ export class FeatureLifecycleService extends EventEmitter {
     }
 
     private async featureArchived(feature: string) {
-        await this.featureLifecycleStore.insert([
+        const result = await this.featureLifecycleStore.insert([
             { feature, stage: 'archived' },
         ]);
-        this.emit(STAGE_ENTERED, { stage: 'archived', feature });
+        this.recordStagesEntered(result);
     }
 
     private async featureRevived(feature: string) {

src/lib/features/feature-lifecycle/feature-lifecycle-store-type.ts

@@ -14,8 +14,12 @@ export type FeatureLifecycleProjectItem = FeatureLifecycleStage & {
     project: string;
 };
 
+export type NewStage = Pick<FeatureLifecycleStage, 'feature' | 'stage'>;
+
 export interface IFeatureLifecycleStore {
-    insert(featureLifecycleStages: FeatureLifecycleStage[]): Promise<void>;
+    insert(
+        featureLifecycleStages: FeatureLifecycleStage[],
+    ): Promise<NewStage[]>;
     get(feature: string): Promise<FeatureLifecycleView>;
     stageExists(stage: FeatureLifecycleStage): Promise<boolean>;
     delete(feature: string): Promise<void>;

src/lib/features/feature-lifecycle/feature-lifecycle-store.ts

@@ -3,6 +3,7 @@ import type {
     IFeatureLifecycleStore,
     FeatureLifecycleView,
     FeatureLifecycleProjectItem,
+    NewStage,
 } from './feature-lifecycle-store-type';
 import type { Db } from '../../db/db';
 import type { StageName } from '../../types';
@@ -38,7 +39,7 @@ export class FeatureLifecycleStore implements IFeatureLifecycleStore {
 
     async insert(
         featureLifecycleStages: FeatureLifecycleStage[],
-    ): Promise<void> {
+    ): Promise<NewStage[]> {
         const existingFeatures = await this.db('features')
             .select('name')
             .whereIn(
@@ -53,9 +54,9 @@ export class FeatureLifecycleStore implements IFeatureLifecycleStore {
         );
 
         if (validStages.length === 0) {
-            return;
+            return [];
         }
-        await this.db('feature_lifecycles')
+        const result = await this.db('feature_lifecycles')
             .insert(
                 validStages.map((stage) => ({
                     feature: stage.feature,
@@ -67,6 +68,11 @@ export class FeatureLifecycleStore implements IFeatureLifecycleStore {
             .returning('*')
             .onConflict(['feature', 'stage'])
             .ignore();
+
+        return result.map((row) => ({
+            stage: row.stage,
+            feature: row.feature,
+        }));
     }
 
     async get(feature: string): Promise<FeatureLifecycleView> {

src/lib/features/feature-lifecycle/feature-lifecycle.e2e.test.ts

@@ -14,13 +14,11 @@ import {
     type StageName,
 } from '../../types';
 import type EventEmitter from 'events';
-import {
-    type FeatureLifecycleService,
-    STAGE_ENTERED,
-} from './feature-lifecycle-service';
+import type { FeatureLifecycleService } from './feature-lifecycle-service';
 import type { FeatureLifecycleCompletedSchema } from '../../openapi';
 import { FeatureLifecycleReadModel } from './feature-lifecycle-read-model';
 import type { IFeatureLifecycleReadModel } from './feature-lifecycle-read-model-type';
+import { STAGE_ENTERED } from '../../metric-events';
 
 let app: IUnleashTest;
 let db: ITestDb;
@@ -102,7 +100,7 @@ const uncompleteFeature = async (featureName: string, expectedCode = 200) => {
 
 function reachedStage(feature: string, stage: StageName) {
     return new Promise((resolve) =>
-        featureLifecycleService.on(STAGE_ENTERED, (event) => {
+        eventBus.on(STAGE_ENTERED, (event) => {
             if (event.stage === stage && event.feature === feature)
                 resolve(stage);
         }),

src/lib/metric-events.ts

@@ -7,6 +7,7 @@ const EVENTS_CREATED_BY_PROCESSED = 'events_created_by_processed';
 const FRONTEND_API_REPOSITORY_CREATED = 'frontend_api_repository_created';
 const PROXY_REPOSITORY_CREATED = 'proxy_repository_created';
 const PROXY_FEATURES_FOR_TOKEN_TIME = 'proxy_features_for_token_time';
+const STAGE_ENTERED = 'stage-entered' as const;
 
 export {
     REQUEST_TIME,
@@ -18,4 +19,5 @@ export {
     FRONTEND_API_REPOSITORY_CREATED,
     PROXY_REPOSITORY_CREATED,
     PROXY_FEATURES_FOR_TOKEN_TIME,
+    STAGE_ENTERED,
 };

src/lib/metrics.test.ts

@@ -320,5 +320,6 @@ test('should collect metrics for lifecycle', async () => {
 
     const metrics = await prometheusRegister.metrics();
     expect(metrics).toMatch(/feature_lifecycle_stage_duration/);
-    expect(metrics).toMatch(/stage_count_by_project/);
+    expect(metrics).toMatch(/feature_lifecycle_stage_count_by_project/);
+    expect(metrics).toMatch(/feature_lifecycle_stage_entered/);
 });

src/lib/metrics.ts

@@ -285,12 +285,18 @@ export default class MetricsMonitor {
             help: 'Duration of feature lifecycle stages',
         });
 
-        const stageCountByProject = createGauge({
-            name: 'stage_count_by_project',
+        const featureLifecycleStageCountByProject = createGauge({
+            name: 'feature_lifecycle_stage_count_by_project',
             help: 'Count features in a given stage by project id',
             labelNames: ['stage', 'project_id'],
         });
 
+        const featureLifecycleStageEnteredCounter = createCounter({
+            name: 'feature_lifecycle_stage_entered',
+            help: 'Count how many features entered a given stage',
+            labelNames: ['stage'],
+        });
+
         const projectEnvironmentsDisabled = createCounter({
             name: 'project_environments_disabled',
             help: 'How many "environment disabled" events we have received for each project',
@@ -337,9 +343,18 @@ export default class MetricsMonitor {
                         .set(stage.duration);
                 });
 
-                stageCountByProject.reset();
+                eventBus.on(
+                    events.STAGE_ENTERED,
+                    (entered: { stage: string; feature: string }) => {
+                        featureLifecycleStageEnteredCounter
+                            .labels({ stage: entered.stage })
+                            .inc();
+                    },
+                );
+
+                featureLifecycleStageCountByProject.reset();
                 stageCountByProjectResult.forEach((stageResult) =>
-                    stageCountByProject
+                    featureLifecycleStageCountByProject
                         .labels({
                             project_id: stageResult.project,
                             stage: stageResult.stage,