feat: Add active users statistics to metrics (#4674)

## About the changes
- `getActiveUsers` is using multiple stores, so it is refactored into
read-model
- Refactored Instance stats service into `features` to co-locate related
code

Closes https://linear.app/unleash/issue/UNL-230/active-users-prometheus

### Important files
`src/lib/features/instance-stats/getActiveUsers.ts`


## Discussion points
`getActiveUsers` is coded less _class-based_ then previous similar
read-models. In one file instead of 3 (read-model interface, fake read
model, sql read model). I find types and functions way more readable,
but I'm ready to refactor it to interfaces and classes if consistency is
more important.

src/lib/db/user-store.ts

@@ -201,31 +201,6 @@ class UserStore implements IUserStore {
             .then((res) => Number(res[0].count));
     }
 
-    async getActiveUsersCount(): Promise<{
-        last7: number;
-        last30: number;
-        last90: number;
-    }> {
-        const result = await this.db.raw(
-            `SELECT
-                (SELECT COUNT(*) FROM ${TABLE} WHERE seen_at > NOW() - INTERVAL '1 week') AS last_week,
-                (SELECT COUNT(*) FROM ${TABLE} WHERE seen_at > NOW() - INTERVAL '1 month') AS last_month,
-                (SELECT COUNT(*) FROM ${TABLE} WHERE seen_at > NOW() - INTERVAL '3 months') AS last_quarter`,
-        );
-
-        const {
-            last_week: last7,
-            last_month: last30,
-            last_quarter: last90,
-        } = result.rows[0];
-
-        return {
-            last7,
-            last30,
-            last90,
-        };
-    }
-
     destroy(): void {}
 
     async exists(id: number): Promise<boolean> {

src/lib/features/instance-stats/getActiveUsers.e2e.test.ts

@@ -0,0 +1,154 @@
+import { createGetActiveUsers, type GetActiveUsers } from './getActiveUsers';
+import dbInit, { type ITestDb } from '../../../test/e2e/helpers/database-init';
+import getLogger from '../../../test/fixtures/no-logger';
+
+let db: ITestDb;
+let getActiveUsers: GetActiveUsers;
+
+const mockUserDaysAgo = (days: number) => {
+    const result = new Date();
+    result.setDate(result.getDate() - days);
+    return {
+        email: `${days}.user@example.com`,
+        seen_at: result,
+    };
+};
+
+const mockTokenDaysAgo = (userId: number, days: number) => {
+    const result = new Date();
+    result.setDate(result.getDate() - days);
+
+    return {
+        user_id: userId,
+        seen_at: result,
+        secret: 'secret',
+        expires_at: new Date('2031-12-31'),
+    };
+};
+
+beforeAll(async () => {
+    db = await dbInit('active_users_serial', getLogger);
+    getActiveUsers = createGetActiveUsers(db.rawDatabase);
+});
+
+afterEach(async () => {
+    await db.rawDatabase('users').delete();
+    await db.rawDatabase('personal_access_tokens').delete();
+});
+
+afterAll(async () => {
+    await db.destroy();
+});
+
+test('should return 0 users', async () => {
+    expect(getActiveUsers()).resolves.toEqual({
+        last7: 0,
+        last30: 0,
+        last60: 0,
+        last90: 0,
+    });
+});
+
+test('should return 1 user', async () => {
+    await db.rawDatabase('users').insert(mockUserDaysAgo(1));
+
+    expect(getActiveUsers()).resolves.toEqual({
+        last7: 1,
+        last30: 1,
+        last60: 1,
+        last90: 1,
+    });
+});
+
+test('should handle intervals of activity', async () => {
+    await db
+        .rawDatabase('users')
+        .insert([
+            mockUserDaysAgo(5),
+            mockUserDaysAgo(10),
+            mockUserDaysAgo(20),
+            mockUserDaysAgo(40),
+            mockUserDaysAgo(70),
+            mockUserDaysAgo(100),
+        ]);
+
+    expect(getActiveUsers()).resolves.toEqual({
+        last7: 1,
+        last30: 3,
+        last60: 4,
+        last90: 5,
+    });
+});
+
+test('should count user as active if they have an active token', async () => {
+    const users = await db
+        .rawDatabase('users')
+        .insert(mockUserDaysAgo(100))
+        .returning('id');
+    const userId = users[0].id;
+    await db
+        .rawDatabase('personal_access_tokens')
+        .insert(mockTokenDaysAgo(userId, 31));
+
+    expect(getActiveUsers()).resolves.toEqual({
+        last7: 0,
+        last30: 0,
+        last60: 1,
+        last90: 1,
+    });
+});
+
+test('should prioritize user seen_at if newer then token seen_at', async () => {
+    const users = await db
+        .rawDatabase('users')
+        .insert(mockUserDaysAgo(14))
+        .returning('id');
+    const userId = users[0].id;
+    await db
+        .rawDatabase('personal_access_tokens')
+        .insert([
+            mockTokenDaysAgo(userId, 31),
+            mockTokenDaysAgo(userId, 61),
+            mockTokenDaysAgo(userId, 91),
+        ]);
+
+    expect(getActiveUsers()).resolves.toEqual({
+        last7: 0,
+        last30: 1,
+        last60: 1,
+        last90: 1,
+    });
+});
+
+test('should handle multiple users and with multiple tokens', async () => {
+    const users = await db
+        .rawDatabase('users')
+        .insert([
+            mockUserDaysAgo(5),
+            mockUserDaysAgo(10),
+            mockUserDaysAgo(20),
+            mockUserDaysAgo(40),
+            mockUserDaysAgo(70),
+            mockUserDaysAgo(100),
+        ])
+        .returning('id');
+
+    await db
+        .rawDatabase('personal_access_tokens')
+        .insert([
+            mockTokenDaysAgo(users[0].id, 31),
+            mockTokenDaysAgo(users[1].id, 61),
+            mockTokenDaysAgo(users[1].id, 15),
+            mockTokenDaysAgo(users[1].id, 55),
+            mockTokenDaysAgo(users[2].id, 4),
+            mockTokenDaysAgo(users[3].id, 91),
+            mockTokenDaysAgo(users[4].id, 91),
+        ]);
+
+    expect(getActiveUsers()).resolves.toEqual({
+        last7: 2,
+        last30: 3,
+        last60: 4,
+        last90: 5,
+    });
+});

src/lib/features/instance-stats/getActiveUsers.ts

@@ -0,0 +1,56 @@
+import { type Db } from 'lib/server-impl';
+
+export type GetActiveUsers = () => Promise<{
+    last7: number;
+    last30: number;
+    last60: number;
+    last90: number;
+}>;
+
+export const createGetActiveUsers =
+    (db: Db): GetActiveUsers =>
+    async () => {
+        const combinedQuery = db
+            .select('id as user_id', 'seen_at')
+            .from('users')
+            .unionAll(
+                db.select('user_id', 'seen_at').from('personal_access_tokens'),
+            );
+
+        const result = await db
+            .with('Combined', combinedQuery)
+            .select({
+                last_week: db.raw(
+                    "COUNT(DISTINCT CASE WHEN seen_at > NOW() - INTERVAL '1 week' THEN user_id END)",
+                ),
+                last_month: db.raw(
+                    "COUNT(DISTINCT CASE WHEN seen_at > NOW() - INTERVAL '1 month' THEN user_id END)",
+                ),
+                last_two_months: db.raw(
+                    "COUNT(DISTINCT CASE WHEN seen_at > NOW() - INTERVAL '2 months' THEN user_id END)",
+                ),
+                last_quarter: db.raw(
+                    "COUNT(DISTINCT CASE WHEN seen_at > NOW() - INTERVAL '3 months' THEN user_id END)",
+                ),
+            })
+            .from('Combined');
+
+        return {
+            last7: parseInt(result?.[0]?.last_week || '0', 10),
+            last30: parseInt(result?.[0]?.last_month || '0', 10),
+            last60: parseInt(result?.[0]?.last_two_months || '0', 10),
+            last90: parseInt(result?.[0]?.last_quarter || '0', 10),
+        };
+    };
+
+export const createFakeGetActiveUsers =
+    (
+        activeUsers: Awaited<ReturnType<GetActiveUsers>> = {
+            last7: 0,
+            last30: 0,
+            last60: 0,
+            last90: 0,
+        },
+    ): GetActiveUsers =>
+    () =>
+        Promise.resolve(activeUsers);

src/lib/features/instance-stats/instance-stats-service.test.ts

@@ -1,7 +1,8 @@
-import { createTestConfig } from '../../test/config/test-config';
+import { createTestConfig } from '../../../test/config/test-config';
 import { InstanceStatsService } from './instance-stats-service';
-import createStores from '../../test/fixtures/store';
+import createStores from '../../../test/fixtures/store';
-import VersionService from './version-service';
+import VersionService from '../../services/version-service';
+import { createFakeGetActiveUsers } from './getActiveUsers';
 
 let instanceStatsService: InstanceStatsService;
 let versionService: VersionService;
@@ -14,6 +15,7 @@ beforeEach(() => {
         stores,
         config,
         versionService,
+        createFakeGetActiveUsers(),
     );
 
     jest.spyOn(instanceStatsService, 'refreshStatsSnapshot');

src/lib/features/instance-stats/instance-stats-service.ts

@@ -1,24 +1,25 @@
 import { sha256 } from 'js-sha256';
-import { Logger } from '../logger';
+import { Logger } from '../../logger';
-import { IUnleashConfig } from '../types/option';
+import { IUnleashConfig } from '../../types/option';
 import {
     IClientInstanceStore,
     IEventStore,
     IUnleashStores,
-} from '../types/stores';
+} from '../../types/stores';
-import { IContextFieldStore } from '../types/stores/context-field-store';
+import { IContextFieldStore } from '../../types/stores/context-field-store';
-import { IEnvironmentStore } from '../types/stores/environment-store';
+import { IEnvironmentStore } from '../../types/stores/environment-store';
-import { IFeatureToggleStore } from '../types/stores/feature-toggle-store';
+import { IFeatureToggleStore } from '../../types/stores/feature-toggle-store';
-import { IGroupStore } from '../types/stores/group-store';
+import { IGroupStore } from '../../types/stores/group-store';
-import { IProjectStore } from '../types/stores/project-store';
+import { IProjectStore } from '../../types/stores/project-store';
-import { IStrategyStore } from '../types/stores/strategy-store';
+import { IStrategyStore } from '../../types/stores/strategy-store';
-import { IActiveUsers, IUserStore } from '../types/stores/user-store';
+import { IUserStore } from '../../types/stores/user-store';
-import { ISegmentStore } from '../types/stores/segment-store';
+import { ISegmentStore } from '../../types/stores/segment-store';
-import { IRoleStore } from '../types/stores/role-store';
+import { IRoleStore } from '../../types/stores/role-store';
-import VersionService from './version-service';
+import VersionService from '../../services/version-service';
-import { ISettingStore } from '../types/stores/settings-store';
+import { ISettingStore } from '../../types/stores/settings-store';
-import { FEATURES_EXPORTED, FEATURES_IMPORTED } from '../types';
+import { FEATURES_EXPORTED, FEATURES_IMPORTED } from '../../types';
-import { CUSTOM_ROOT_ROLE_TYPE } from '../util';
+import { CUSTOM_ROOT_ROLE_TYPE } from '../../util';
+import { type GetActiveUsers } from './getActiveUsers';
 
 export type TimeRange = 'allTime' | '30d' | '7d';
 
@@ -43,7 +44,7 @@ export interface InstanceStats {
     SAMLenabled: boolean;
     OIDCenabled: boolean;
     clientApps: { range: TimeRange; count: number }[];
-    activeUsers: IActiveUsers;
+    activeUsers: Awaited<ReturnType<GetActiveUsers>>;
 }
 
 export interface InstanceStatsSigned extends InstanceStats {
@@ -83,6 +84,8 @@ export class InstanceStatsService {
 
     private appCount?: Partial<{ [key in TimeRange]: number }>;
 
+    private getActiveUsers: GetActiveUsers;
+
     constructor(
         {
             featureToggleStore,
@@ -114,6 +117,7 @@ export class InstanceStatsService {
         >,
         { getLogger }: Pick<IUnleashConfig, 'getLogger'>,
         versionService: VersionService,
+        getActiveUsers: GetActiveUsers,
     ) {
         this.strategyStore = strategyStore;
         this.userStore = userStore;
@@ -129,6 +133,7 @@ export class InstanceStatsService {
         this.eventStore = eventStore;
         this.clientInstanceStore = clientInstanceStore;
         this.logger = getLogger('services/stats-service.js');
+        this.getActiveUsers = getActiveUsers;
     }
 
     async refreshStatsSnapshot(): Promise<void> {
@@ -195,7 +200,7 @@ export class InstanceStatsService {
         ] = await Promise.all([
             this.getToggleCount(),
             this.userStore.count(),
-            this.userStore.getActiveUsersCount(),
+            this.getActiveUsers(),
             this.projectStore.count(),
             this.contextFieldStore.count(),
             this.groupStore.count(),

src/lib/metrics.test.ts

@@ -10,8 +10,9 @@ import {
 } from './types/events';
 import { createMetricsMonitor } from './metrics';
 import createStores from '../test/fixtures/store';
-import { InstanceStatsService } from './services/instance-stats-service';
+import { InstanceStatsService } from './features/instance-stats/instance-stats-service';
 import VersionService from './services/version-service';
+import { createFakeGetActiveUsers } from './features/instance-stats/getActiveUsers';
 
 const monitor = createMetricsMonitor();
 const eventBus = new EventEmitter();
@@ -28,7 +29,13 @@ beforeAll(() => {
     stores = createStores();
     eventStore = stores.eventStore;
     const versionService = new VersionService(stores, config);
-    statsService = new InstanceStatsService(stores, config, versionService);
+    statsService = new InstanceStatsService(
+        stores,
+        config,
+        versionService,
+        createFakeGetActiveUsers(),
+    );
+
     const db = {
         client: {
             pool: {

src/lib/metrics.ts

@@ -22,7 +22,7 @@ import { IUnleashConfig } from './types/option';
 import { IUnleashStores } from './types/stores';
 import { hoursToMilliseconds, minutesToMilliseconds } from 'date-fns';
 import Timer = NodeJS.Timer;
-import { InstanceStatsService } from './services/instance-stats-service';
+import { InstanceStatsService } from './features/instance-stats/instance-stats-service';
 import { ValidatedClientMetrics } from './services/client-metrics/schema';
 
 export default class MetricsMonitor {
@@ -86,6 +86,22 @@ export default class MetricsMonitor {
             name: 'users_total',
             help: 'Number of users',
         });
+        const usersActive7days = new client.Gauge({
+            name: 'users_active_7',
+            help: 'Number of users active in the last 7 days',
+        });
+        const usersActive30days = new client.Gauge({
+            name: 'users_active_30',
+            help: 'Number of users active in the last 30 days',
+        });
+        const usersActive60days = new client.Gauge({
+            name: 'users_active_60',
+            help: 'Number of users active in the last 60 days',
+        });
+        const usersActive90days = new client.Gauge({
+            name: 'users_active_90',
+            help: 'Number of users active in the last 90 days',
+        });
         const projectsTotal = new client.Gauge({
             name: 'projects_total',
             help: 'Number of projects',
@@ -167,6 +183,15 @@ export default class MetricsMonitor {
                 usersTotal.reset();
                 usersTotal.set(stats.users);
 
+                usersActive7days.reset();
+                usersActive7days.set(stats.activeUsers.last7);
+                usersActive30days.reset();
+                usersActive30days.set(stats.activeUsers.last30);
+                usersActive60days.reset();
+                usersActive60days.set(stats.activeUsers.last60);
+                usersActive90days.reset();
+                usersActive90days.set(stats.activeUsers.last90);
+
                 projectsTotal.reset();
                 projectsTotal.set(stats.projects);
 

src/lib/openapi/spec/instance-admin-stats-schema.ts

@@ -58,6 +58,13 @@ export const instanceAdminStatsSchema = {
                     example: 10,
                     minimum: 0,
                 },
+                last60: {
+                    type: 'number',
+                    description:
+                        'The number of active users in the last 60 days',
+                    example: 12,
+                    minimum: 0,
+                },
                 last90: {
                     type: 'number',
                     description:

src/lib/routes/admin-api/instance-admin.ts

@@ -10,7 +10,7 @@ import {
     InstanceStats,
     InstanceStatsService,
     InstanceStatsSigned,
-} from '../../services/instance-stats-service';
+} from '../../features/instance-stats/instance-stats-service';
 import { OpenApiService } from '../../services/openapi-service';
 import {
     createCsvResponseSchema,
@@ -110,6 +110,7 @@ class InstanceAdminController extends Controller {
             versionOSS: '5.1.7',
             activeUsers: {
                 last90: 15,
+                last60: 12,
                 last30: 10,
                 last7: 5,
             },

src/lib/services/index.ts

@@ -36,7 +36,7 @@ import EdgeService from './edge-service';
 import PatService from './pat-service';
 import { PublicSignupTokenService } from './public-signup-token-service';
 import { LastSeenService } from './client-metrics/last-seen-service';
-import { InstanceStatsService } from './instance-stats-service';
+import { InstanceStatsService } from '../features/instance-stats/instance-stats-service';
 import { FavoritesService } from './favorites-service';
 import MaintenanceService from './maintenance-service';
 import {
@@ -64,6 +64,10 @@ import {
     createFakePrivateProjectChecker,
     createPrivateProjectChecker,
 } from '../features/private-project/createPrivateProjectChecker';
+import {
+    createFakeGetActiveUsers,
+    createGetActiveUsers,
+} from '../features/instance-stats/getActiveUsers';
 
 // TODO: will be moved to scheduler feature directory
 export const scheduleServices = async (
@@ -262,6 +266,7 @@ export const createServices = (
         stores,
         config,
         versionService,
+        db ? createGetActiveUsers(db) : createFakeGetActiveUsers(),
     );
 
     const schedulerService = new SchedulerService(config.getLogger);

src/lib/types/services.ts

@@ -33,7 +33,7 @@ import EdgeService from '../services/edge-service';
 import PatService from '../services/pat-service';
 import { PublicSignupTokenService } from '../services/public-signup-token-service';
 import { LastSeenService } from '../services/client-metrics/last-seen-service';
-import { InstanceStatsService } from '../services/instance-stats-service';
+import { InstanceStatsService } from '../features/instance-stats/instance-stats-service';
 import { FavoritesService } from '../services/favorites-service';
 import MaintenanceService from '../services/maintenance-service';
 import { AccountService } from '../services/account-service';

src/lib/types/stores/user-store.ts

@@ -19,12 +19,6 @@ export interface IUserUpdateFields {
     email?: string;
 }
 
-export interface IActiveUsers {
-    last7: number;
-    last30: number;
-    last90: number;
-}
-
 export interface IUserStore extends Store<IUser, number> {
     update(id: number, fields: IUserUpdateFields): Promise<IUser>;
     insert(user: ICreateUser): Promise<IUser>;
@@ -38,5 +32,4 @@ export interface IUserStore extends Store<IUser, number> {
     incLoginAttempts(user: IUser): Promise<void>;
     successfullyLogin(user: IUser): Promise<void>;
     count(): Promise<number>;
-    getActiveUsersCount(): Promise<IActiveUsers>;
 }

src/test/fixtures/fake-user-store.ts

@@ -1,6 +1,5 @@
 import User, { IUser } from '../../lib/types/user';
 import {
-    IActiveUsers,
     ICreateUser,
     IUserLookup,
     IUserStore,
@@ -47,26 +46,6 @@ class UserStoreMock implements IUserStore {
         return this.data.find((u) => u.id === key);
     }
 
-    async getActiveUsersCount(): Promise<IActiveUsers> {
-        return Promise.resolve({
-            last7: this.data.filter(
-                (u) =>
-                    u.seenAt &&
-                    u.seenAt > new Date(Date.now() - 7 * 24 * 60 * 60 * 1000),
-            ).length,
-            last30: this.data.filter(
-                (u) =>
-                    u.seenAt &&
-                    u.seenAt > new Date(Date.now() - 30 * 24 * 60 * 60 * 1000),
-            ).length,
-            last90: this.data.filter(
-                (u) =>
-                    u.seenAt &&
-                    u.seenAt > new Date(Date.now() - 90 * 24 * 60 * 60 * 1000),
-            ).length,
-        });
-    }
-
     async insert(user: User): Promise<User> {
         // eslint-disable-next-line no-param-reassign
         user.id = this.idSeq;