logger.module.ts

import { Module } from '@nestjs/common';
import { ConfigModule, ConfigService } from '@nestjs/config';
import { LoggerModule as PinoLoggerModule } from 'nestjs-pino';

/**
 * Structured logging built on Pino. In development logs are pretty-printed for
 * readability; in production they are emitted as JSON for log aggregation.
 */
@Module({
  imports: [
    PinoLoggerModule.forRootAsync({
      imports: [ConfigModule],
      inject: [ConfigService],
      useFactory: (config: ConfigService) => {
        const isProduction = config.get<string>('app.nodeEnv') === 'production';

        return {
          pinoHttp: {
            level: config.get<string>('app.logLevel') ?? 'info',
            transport: isProduction
              ? undefined
              : {
                  target: 'pino-pretty',
                  options: {
                    singleLine: true,
                    translateTime: 'SYS:standard',
                    ignore: 'pid,hostname',
                  },
                },
          },
        };
      },
    }),
  ],
})
export class LoggerModule {}