add tldraw application level metrics

apps/server/src/modules/tldraw/metrics/index.ts

@@ -0,0 +1 @@
+export * from './metrics.service';

apps/server/src/modules/tldraw/metrics/metrics.service.ts

@@ -0,0 +1,40 @@
+import { Injectable } from '@nestjs/common';
+import { Gauge, register } from 'prom-client';
+
+@Injectable()
+export class MetricsService {
+	private numberOfUsersOnServerCounter: Gauge<string>;
+
+	private numberOfBoardsOnServerCounter: Gauge<string>;
+
+	constructor() {
+		this.numberOfUsersOnServerCounter = new Gauge({
+			name: 'sc_tldraw_users',
+			help: 'Number of active users per pod',
+		});
+
+		this.numberOfBoardsOnServerCounter = new Gauge({
+			name: 'sc_tldraw_boards',
+			help: 'Number of active boards per pod',
+		});
+
+		register.registerMetric(this.numberOfUsersOnServerCounter);
+		register.registerMetric(this.numberOfBoardsOnServerCounter);
+	}
+
+	public incrementNumberOfUsersOnServerCounter(): void {
+		this.numberOfUsersOnServerCounter.inc();
+	}
+
+	public decrementNumberOfUsersOnServerCounter(): void {
+		this.numberOfUsersOnServerCounter.dec();
+	}
+
+	public incrementNumberOfBoardsOnServerCounter(): void {
+		this.numberOfBoardsOnServerCounter.inc();
+	}
+
+	public decrementNumberOfBoardsOnServerCounter(): void {
+		this.numberOfBoardsOnServerCounter.dec();
+	}
+}

apps/server/src/modules/tldraw/service/tldraw.ws.service.spec.ts

@@ -10,6 +10,7 @@ import * as SyncProtocols from 'y-protocols/sync';
 import * as AwarenessProtocol from 'y-protocols/awareness';
 import { encoding } from 'lib0';
 import { TldrawWsFactory } from '@shared/testing/factory/tldraw.ws.factory';
+import { MetricsService } from '@modules/tldraw/metrics';
 import { WsSharedDocDo } from '../domain/ws-shared-doc.do';
 import { config } from '../config';
 import { TldrawBoardRepo } from '../repo';
@@ -51,7 +52,7 @@ describe('TldrawWSService', () => {
 		const imports = [CoreModule, ConfigModule.forRoot(createConfigModuleOptions(config))];
 		const testingModule = await Test.createTestingModule({
 			imports,
-			providers: [TldrawWs, TldrawBoardRepo, TldrawWsService],
+			providers: [TldrawWs, TldrawBoardRepo, TldrawWsService, MetricsService],
 		}).compile();
 
 		service = testingModule.get<TldrawWsService>(TldrawWsService);

apps/server/src/modules/tldraw/service/tldraw.ws.service.ts

@@ -8,6 +8,7 @@ import { Persitence, WSConnectionState, WSMessageType } from '../types';
 import { TldrawConfig } from '../config';
 import { WsSharedDocDo } from '../domain/ws-shared-doc.do';
 import { TldrawBoardRepo } from '../repo';
+import { MetricsService } from '../metrics';
 
 @Injectable()
 export class TldrawWsService {
@@ -19,7 +20,8 @@ export class TldrawWsService {
 
 	constructor(
 		private readonly configService: ConfigService<TldrawConfig, true>,
-		private readonly tldrawBoardRepo: TldrawBoardRepo
+		private readonly tldrawBoardRepo: TldrawBoardRepo,
+		private readonly metricsService: MetricsService
 	) {
 		this.pingTimeout = this.configService.get<number>('TLDRAW_PING_TIMEOUT');
 	}
@@ -47,7 +49,9 @@ export class TldrawWsService {
 					})
 					.catch(() => {});
 				this.docs.delete(doc.name);
+				this.metricsService.decrementNumberOfBoardsOnServerCounter();
 			}
+			this.metricsService.decrementNumberOfUsersOnServerCounter();
 		}
 
 		try {
@@ -106,6 +110,7 @@ export class TldrawWsService {
 				this.persistence.bindState(docName, doc).catch(() => {});
 			}
 			this.docs.set(docName, doc);
+			this.metricsService.incrementNumberOfBoardsOnServerCounter();
 			return doc;
 		});
 	}
@@ -197,6 +202,7 @@ export class TldrawWsService {
 				this.send(doc, ws, encoding.toUint8Array(encoder));
 			}
 		}
+		this.metricsService.incrementNumberOfUsersOnServerCounter();
 	}
 
 	public async updateDocument(docName: string, ydoc: WsSharedDocDo): Promise<void> {

apps/server/src/modules/tldraw/tldraw-test.module.ts

@@ -5,6 +5,7 @@ import { LoggerModule } from '@src/core/logger';
 import { AuthenticationModule } from '@modules/authentication/authentication.module';
 import { AuthorizationModule } from '@modules/authorization';
 import { Course, User } from '@shared/domain/entity';
+import { MetricsService } from '@modules/tldraw/metrics';
 import { AuthenticationApiModule } from '../authentication/authentication-api.module';
 import { TldrawWsModule } from './tldraw-ws.module';
 import { TldrawWs } from './controller';
@@ -20,7 +21,7 @@ const imports = [
 	CoreModule,
 	LoggerModule,
 ];
-const providers = [TldrawWs, TldrawBoardRepo, TldrawWsService];
+const providers = [TldrawWs, TldrawBoardRepo, TldrawWsService, MetricsService];
 @Module({
 	imports,
 	providers,

apps/server/src/modules/tldraw/tldraw-ws-test.module.ts

@@ -3,13 +3,14 @@ import { MongoMemoryDatabaseModule, MongoDatabaseModuleOptions } from '@infra/da
 import { CoreModule } from '@src/core';
 import { ConfigModule } from '@nestjs/config';
 import { createConfigModuleOptions } from '@src/config';
+import { MetricsService } from '@modules/tldraw/metrics';
 import { TldrawBoardRepo } from './repo';
 import { TldrawWsService } from './service';
 import { config } from './config';
 import { TldrawWs } from './controller';
 
 const imports = [CoreModule, ConfigModule.forRoot(createConfigModuleOptions(config))];
-const providers = [TldrawWs, TldrawBoardRepo, TldrawWsService];
+const providers = [TldrawWs, TldrawBoardRepo, TldrawWsService, MetricsService];
 @Module({
 	imports,
 	providers,

apps/server/src/modules/tldraw/tldraw-ws.module.ts

@@ -3,13 +3,14 @@ import { ConfigModule } from '@nestjs/config';
 import { createConfigModuleOptions } from '@src/config';
 import { CoreModule } from '@src/core';
 import { Logger } from '@src/core/logger';
+import { MetricsService } from '@modules/tldraw/metrics';
 import { TldrawBoardRepo } from './repo';
 import { TldrawWsService } from './service';
 import { TldrawWs } from './controller';
 import { config } from './config';
 
 @Module({
 	imports: [CoreModule, ConfigModule.forRoot(createConfigModuleOptions(config))],
-	providers: [Logger, TldrawWs, TldrawWsService, TldrawBoardRepo],
+	providers: [Logger, TldrawWs, TldrawWsService, TldrawBoardRepo, MetricsService],
 })
 export class TldrawWsModule {}