winston_logger_with_file_and_console_transports.ts

1import * as winston from 'winston';
2
3const logger = winston.createLogger({
4  level: 'info',
5  format: winston.format.json(),
6  defaultMeta: { service: 'user-service' },
7  transports: [
8    //
9    // - Write all logs with importance level of `error` or less to `error.log`
10    // - Write all logs with importance level of `info` or less to `combined.log`
11    //
12    new winston.transports.File({ filename: 'error.log', level: 'error' }),
13    new winston.transports.File({ filename: 'combined.log' }),
14  ],
15});
16
17//
18// If we're not in production then log to the `console` with the format:
19// `${info.level}: ${info.message} JSON.stringify({ ...rest }) `
20//
21if (process.env.NODE_ENV !== 'production') {
22  logger.add(new winston.transports.Console({
23    format: winston.format.simple(),
24  }));
25}
26
27// Example logs
28logger.info('Hello world!');
29logger.error('Something went wrong');