Winston not displaying error details

Question

I am using winston for logging and most of the time it works well, but when there is an exception, it just does not print any details.

Here is my code for configuring winston:

// Create logger
const logger = winston.createLogger()

// Create timestamp format
const tsFormat = () => (new Date()).toLocaleTimeString()

// Attach transports based on app mode
if (process.env.APP_MODE === 'production') {
  // Log to file
  logger.add(new (winston.transports.DailyRotateFile)({
    filename: path.join(__dirname, '../logs/errors-%DATE%.log'),
    datePattern: 'YYYY-MM-DD-HH',
    zippedArchive: true,
    format: winston.format.json(),
    handleExceptions: true
  }))
} else {
  // Log to the console
  logger.add(new (winston.transports.Console)({
    timestamp: tsFormat,
    colorize: true,
    handleExceptions: true
  }))
}

module.exports = logger

I am also using Express and in my error handling middleware, I have this code:

const logger = require('../config/winston')
function (err, req, res, next) {
    console.log(err)
    logger.error(err)
    res.status(500).send({ error: 'Please try again later.' })
}

The problem is that when an error occurs all winston logs is:

{"level":"error"}

While the good old console.log() displays:

TypeError: Cannot read property 'filename' of undefined
    at router.post (/Users/balazsvincze/Desktop/testapi/app/routes/upload.js:16:33)
    at Layer.handle [as handle_request] (/Users/de/Desktop/testapi/node_modules/express/lib/router/layer.js:95:5)
    at next (/Users/balazsvincze/Desktop/testapi/node_modules/express/lib/router/route.js:137:13)
    at Immediate.<anonymous> (/Users/balazsvincze/Desktop/testapi/node_modules/multer/lib/make-middleware.js:53:37)
    at runCallback (timers.js:814:20)
    at tryOnImmediate (timers.js:768:5)
    at processImmediate [as _immediateCallback] (timers.js:745:5)

How do I get winston to log something like this including the stack trace?

Many thanks!

EDIT: If I change the line logger.error(err) to logger.error(err.message), at least I get this:

{"message":"Cannot read property 'filename' of undefined","level":"error"}

Still very far off from what I am after.

Answer 1

A quick and dirty way would be to log err.stack:

logger.error(err.stack);

A more elaborate method would be to implement a custom format specifically for Error instances. There's some example code on how to implement that in this Github issue.