feat(logger): add Loki transport for Winston

Author: soorq

.env.example

@@ -49,4 +49,6 @@ S3_ACCESS_KEY=''
 S3_SECRET_KEY=''
 
 IMAGOR_SECRET=''
-IMAGOR_URL=''
+IMAGOR_URL=''
+
+LOKI_HOST=''

libs/bootstrap/src/bootstrap.ts

@@ -2,7 +2,7 @@ import { Logger, VersioningType } from '@nestjs/common';
 import { ConfigService } from '@nestjs/config';
 import { NestFactory } from '@nestjs/core';
 import { DEFAULT_THROTTLER_OPTIONS } from './configs/throttler';
-import { setupCors, setupLogger, setupThrottler, setupSwagger, LoggingInterceptor } from './setups';
+import { setupCors, setupLogger, setupThrottler, setupSwagger } from './setups';
 import { FastifyAdapter, type NestFastifyApplication } from '@nestjs/platform-fastify';
 import type { BootstrapOptions } from './interfaces/options.interface';
 import fastifyCookie from '@fastify/cookie';
@@ -21,8 +21,6 @@ export async function bootstrapApp(options: BootstrapOptions) {
         },
     });
 
-    const winston = setupLogger(options.serviceName);
-
     const {
         appModule,
         apiPrefix,
@@ -48,8 +46,6 @@ export async function bootstrapApp(options: BootstrapOptions) {
         bufferLogs: true,
     });
 
-    app.useLogger(winston);
-
     const logger = new Logger(serviceName[0].toUpperCase() + serviceName.slice(1));
     const configService = app.get(ConfigService);
     const port = configService.getOrThrow<number>(portEnvKey, defaultPort);
@@ -64,7 +60,7 @@ export async function bootstrapApp(options: BootstrapOptions) {
             return payload;
         });
 
-    app.useGlobalInterceptors(new LoggingInterceptor());
+    await setupLogger(app, options.serviceName);
 
     await app.register(fastifyCompress, {
         global: true,

libs/bootstrap/src/setups/index.ts

@@ -1,4 +1,4 @@
 export { setupCors } from './cors';
 export { setupThrottler } from './throttler';
 export { setupSwagger } from './swagger';
-export { setupLogger, LoggingInterceptor } from './logger';
+export { setupLogger } from './logger';

libs/bootstrap/src/setups/logger.ts

@@ -9,42 +9,66 @@ import { Observable, throwError } from 'rxjs';
 import { tap, catchError } from 'rxjs/operators';
 import type { FastifyRequest } from 'fastify';
 import { WinstonModule, utilities } from 'nest-winston';
-import { format, transports } from 'winston';
+import { format, transport, transports } from 'winston';
+import Loki from 'winston-loki';
+import type { NestFastifyApplication } from '@nestjs/platform-fastify';
+import { ConfigService } from '@nestjs/config';
 
-export function setupLogger(service: string) {
-    const isProduction = process.env.NODE_ENV === 'production';
+export function setupLogger(app: NestFastifyApplication, service: string) {
+    const cfg = app.get(ConfigService);
 
-    return WinstonModule.createLogger({
-        level: isProduction ? 'info' : 'debug',
-        transports: [
-            new transports.Console({
-                format: format.combine(
-                    format.timestamp({ format: 'YYYY-MM-DD HH:mm:ss' }),
-                    format.ms(),
-                    format.errors({ stack: true }),
-                    format.metadata({ fillExcept: ['message', 'level', 'timestamp', 'context'] }),
-                    format((info) => {
-                        const mask = (obj: any) => {
-                            const sensitive = ['password', 'token', 'secret', 'authorization'];
-                            for (const key in obj) {
-                                if (sensitive.includes(key.toLowerCase())) obj[key] = '***';
-                                else if (typeof obj[key] === 'object') mask(obj[key]);
-                            }
-                        };
-                        if (info.metadata) mask(info.metadata);
-                        return info;
-                    })(),
-
-                    isProduction
-                        ? format.json()
-                        : utilities.format.nestLike(service, {
-                              colors: true,
-                              prettyPrint: false,
-                          }),
-                ),
+    const isProduction = cfg.get('NODE_ENV') === 'production';
+    const loki = cfg.get('LOKI_HOST');
+
+    const transportsList: transport[] = [
+        new transports.Console({
+            format: format.combine(
+                format.timestamp({ format: 'YYYY-MM-DD HH:mm:ss' }),
+                format.ms(),
+                format.errors({ stack: true }),
+                format.metadata({ fillExcept: ['message', 'level', 'timestamp', 'context'] }),
+                format((info) => {
+                    const mask = (obj: any) => {
+                        const sensitive = ['password', 'token', 'secret', 'authorization'];
+                        for (const key in obj) {
+                            if (sensitive.includes(key.toLowerCase())) obj[key] = '***';
+                            else if (typeof obj[key] === 'object') mask(obj[key]);
+                        }
+                    };
+                    if (info.metadata) mask(info.metadata);
+                    return info;
+                })(),
+
+                isProduction
+                    ? format.json()
+                    : utilities.format.nestLike(service, {
+                          colors: true,
+                          prettyPrint: false,
+                      }),
+            ),
+        }),
+    ];
+
+    if (loki) {
+        transportsList.push(
+            new Loki({
+                host: loki,
+                labels: { app: service },
+                json: true,
+                format: format.json(),
+                replaceTimestamp: true,
+                onConnectionError: (err) => console.error('Loki connection error:', err),
             }),
-        ],
+        );
+    }
+
+    const logger = WinstonModule.createLogger({
+        level: isProduction ? 'info' : 'debug',
+        transports: transportsList,
     });
+
+    app.useLogger(logger);
+    app.useGlobalInterceptors(new LoggingInterceptor());
 }
 
 @Injectable()

libs/config/src/config.schema.ts

@@ -91,6 +91,7 @@ export const ConfigSchema = z.object({
     S3_SECRET_KEY: z.string({
         error: 'S3_SECRET_KEY is missing (MinIO root password or IAM secret)',
     }),
+    LOKI_HOST: z.string().url().min(1).optional(),
 });
 
 export type Config = z.infer<typeof ConfigSchema>;

package.json

@@ -79,6 +79,7 @@
         "transliteration": "^2.6.1",
         "ua-parser-js": "^2.0.9",
         "winston": "^3.19.0",
+        "winston-loki": "^6.1.4",
         "zod": "^4.3.6"
     },
     "devDependencies": {