How to Log Full Stack Trace with Winston 3?

My logger is set up like:

const myFormat = printf(info => {
   return `${info.timestamp}: ${info.level}: ${info.message}: ${info.err}`;
 });


 const logger =
   winston.createLogger({
   level: "info",
   format: combine(timestamp(), myFormat),

   transports: [
     new winston.transports.File({
     filename:
      "./logger/error.log",
        level: "error"
    }),
     new winston.transports.File({
       filename:
       "./logger/info.log",
       level: "info"
   })
  ]
})

Then I am logging out some error like this:

logger.error(`GET on /history`, { err });

How is it possible to log the full stack trace for errors to via the error transport? I tried passing in the err.stack and it came out as undefined.

Thanks !

Solution 1:

For winston version 3.2.0+, following will add stacktrace to log output:

import { createLogger, format, transports } from 'winston';

const { combine, timestamp, prettyPrint, colorize, errors,  } = format;


const logger = createLogger({
  format: combine(
    errors({ stack: true }), // <-- use errors format
    colorize(),
    timestamp(),
    prettyPrint()
  ),
  transports: [new transports.Console()],
});  

Ref: https://github.com/winstonjs/winston/issues/1338#issuecomment-482784056

Solution 2:

You can write a formatter to pass error.stack to log.

const errorStackFormat = winston.format(info => {
  if (info instanceof Error) {
    return Object.assign({}, info, {
      stack: info.stack,
      message: info.message
    })
  }
  return info
})

const logger = winston.createLogger({
  transports: [ ... ],
  format: winston.format.combine(errorStackFormat(), myFormat)
})

logger.info(new Error('yo')) // => {message: 'yo', stack: "Error blut at xxx.js:xx ......"} 

(the output will depend on your configuration)

Solution 3:

UPDATE 1/14/2021 - This no longer works in newer versions of Winston.

Original Answer

@Ming's answer got me partly there, but to have a string description with the error, this is how I got full stack tracing working on ours:

import winston from "winston";

const errorStackTracerFormat = winston.format(info => {
    if (info.meta && info.meta instanceof Error) {
        info.message = `${info.message} ${info.meta.stack}`;
    }
    return info;
});

const logger = winston.createLogger({
    format: winston.format.combine(
        winston.format.splat(), // Necessary to produce the 'meta' property
        errorStackTracerFormat(),
        winston.format.simple()
    )
});

logger.error("Does this work?", new Error("Yup!"));

// The log output:
//   error: Does this work? Error: Yup!
//       at Object.<anonymous> (/path/to/file.ts:18:33)
//       at ...
//       at ...