feat: loki

Author: naman22a

apps/api-gateway/package.json

@@ -32,6 +32,7 @@
         "@nestjs/platform-socket.io": "^11.1.9",
         "@nestjs/swagger": "^11.2.1",
         "@nestjs/websockets": "^11.1.9",
+        "axios": "^1.13.2",
         "bullmq": "^5.63.1",
         "class-transformer": "^0.5.1",
         "class-validator": "^0.14.2",

apps/api-gateway/src/logging/loki-logger.service.ts

@@ -0,0 +1,43 @@
+import { Injectable, LoggerService } from '@nestjs/common';
+import axios from 'axios';
+
+@Injectable()
+export class LokiLogger implements LoggerService {
+    private lokiUrl = process.env.LOKI_URL ?? 'http://loki:3100/loki/api/v1/push';
+    private appName = process.env.APP_NAME ?? 'api-gateway';
+
+    log(message: string, context?: string) {
+        this.sendLog('info', message, context);
+        console.log(`[INFO]${context ? ` [${context}]` : ''} ${message}`);
+    }
+
+    error(message: string, trace?: string, context?: string) {
+        this.sendLog('error', `${message} ${trace || ''}`, context);
+        console.error(`[ERROR]${context ? ` [${context}]` : ''} ${message}`, trace);
+    }
+
+    warn(message: string, context?: string) {
+        this.sendLog('warn', message, context);
+        console.warn(`[WARN]${context ? ` [${context}]` : ''} ${message}`);
+    }
+
+    debug(message: string, context?: string) {
+        this.sendLog('debug', message, context);
+        console.debug(`[DEBUG]${context ? ` [${context}]` : ''} ${message}`);
+    }
+
+    private async sendLog(level: string, msg: string, context?: string) {
+        try {
+            await axios.post(this.lokiUrl, {
+                streams: [
+                    {
+                        stream: { level, app: this.appName, context: context || 'default' },
+                        values: [[`${Date.now() * 1_000_000}`, msg]], // nanoseconds
+                    },
+                ],
+            });
+        } catch (err) {
+            console.error('Failed to send log to Loki', err);
+        }
+    }
+}

apps/api-gateway/src/logging/loki-logging.interceptor.ts

@@ -0,0 +1,31 @@
+import { Injectable, NestInterceptor, ExecutionContext, CallHandler } from '@nestjs/common';
+import { Observable, tap } from 'rxjs';
+import { LokiLogger } from './loki-logger.service';
+
+@Injectable()
+export class LokiLoggingInterceptor implements NestInterceptor {
+    constructor(private readonly logger: LokiLogger) {}
+
+    intercept(context: ExecutionContext, next: CallHandler): Observable<any> {
+        const req = context.switchToHttp().getRequest();
+        const { method, url, body } = req;
+        const start = Date.now();
+
+        return next.handle().pipe(
+            tap({
+                next: (res) => {
+                    const ms = Date.now() - start;
+                    this.logger.log(`${method} ${url} ${res?.statusCode || 200} - ${ms}ms`, 'HTTP');
+                },
+                error: (err) => {
+                    const ms = Date.now() - start;
+                    this.logger.error(
+                        `${method} ${url} - ${err.message} - ${ms}ms`,
+                        err.stack,
+                        'HTTP',
+                    );
+                },
+            }),
+        );
+    }
+}

apps/api-gateway/src/main.ts

@@ -6,6 +6,8 @@ import cookieParser from 'cookie-parser';
 import { DocumentBuilder, SwaggerModule } from '@nestjs/swagger';
 import { ConfigService } from '@nestjs/config';
 import { Configuration } from '@leetcode/config';
+import { LokiLogger } from './logging/loki-logger.service';
+import { LokiLoggingInterceptor } from './logging/loki-logging.interceptor';
 
 declare global {
     namespace Express {
@@ -17,6 +19,7 @@ declare global {
 
 async function bootstrap() {
     const app = await NestFactory.create(AppModule);
+    const logger = new LokiLogger();
 
     // CONFIGURATION
     const configService = app.get(ConfigService<Configuration>);
@@ -26,6 +29,9 @@ async function bootstrap() {
     // VALIDATION
     app.useGlobalPipes(new ValidationPipe({ exceptionFactory }));
 
+    // LOGGING
+    app.useGlobalInterceptors(new LokiLoggingInterceptor(logger));
+
     // MIDDLWARE
     app.use(cookieParser());
     app.enableCors({

docker-compose.yml

@@ -347,6 +347,13 @@ services:
             - "3001:3000"
         restart: unless-stopped
 
+    loki:
+        image: grafana/loki:latest
+        container_name: loki
+        ports:
+            - "3100:3100"
+        restart: unless-stopped
+
 volumes:
     pgdata:
     redis-data: