Winston not creating any output when running in a Docker container

Please tell us about your environment:

• winston version?
  • winston@2
  • winston@3
• node -v outputs: v14.5.0
• Operating System? (Windows, macOS, or Linux) macOS + Alpine Linux
• Language? (all | TypeScript X.X | ES6/7 | ES5 | Dart) ES6/7

What is the problem?

Winston does not print any log output when running inside a Docker container, either to the Console or to a file (it does create the file, just doesn’t put any output there.)

Here is my Winston config.

import winston from 'winston'
import config from '../config'

const transports = []

transports.push(
  new winston.transports.Console(),
  new winston.transports.File({
    filename: 'test.log'
  })
)

const LoggerInstance = winston.createLogger({
  level: config.logs.level,
  levels: winston.config.npm.levels,
  format: winston.format.combine(
    winston.format.timestamp({
      format: 'YYYY-MM-DD HH:mm:ss'
    }),
    winston.format.errors({ stack: true }),
    winston.format.splat(),
    winston.format.json()
  ),
  transports
})

export default LoggerInstance

This is my Dockerfile

FROM node:current-alpine

WORKDIR /usr/src
RUN apk --no-cache add --virtual builds-deps build-base python
COPY package.json package.json
COPY package-lock.json package-lock.json
RUN npm install
COPY . .
ENV NODE_ENV production

CMD ["npm", "run", "start"]

Here is where I’m logging

import expressLoader from './express'
import databaseLoader from './database'
import dependencyLoader from './dependencies'
import modelLoader from './models'
import Logger from './logger'

export default async ({ expressApp }) => {
  const conn = databaseLoader
  Logger.info('✅️ Database loaded')

  try {
    await conn.authenticate()
    Logger.info('🔌 ️Database connected')
  } catch (e) {
    Logger.error('🔥 Error connecting to database: %o', e)
    process.exit(1)
  }

  Logger.info('➕ Injecting dependencies')
  dependencyLoader()
  Logger.info('✅️ Dependencies injected')

  Logger.info('➕ Injecting models')
  modelLoader()
  Logger.info('✅️ Models injected')

  expressLoader({ app: expressApp })
  Logger.info('✅️ Express loaded')
}

I get the following output when running locally

And when I run from my Docker container, I get the following

If I change all of the Logger.info to console.log, I get output.

The log level (and all other config) is the same, and is currently set to silly.

Any ideas?

[indrasenakatam]

Can you please help me how to write logs into winston file transports using docker container.

using docker able to create logs file and console logs printing in server using docker image.

But the logs are not saved into log files.

So can you please suggest how to write logs into winston file transports using docker image.

WORKDIR /home/app
RUN mkdir -p /path/to/logs && \
    touch /path/to/logs/error.log && \
    touch //path/to/logs/combined.log && \
    chmod 777 /path/to/logs/*

still winston file transport not able to save logs into files. In local environment without docker image it’s working as expected.

Please suggest me how to write & save logs into files using docker image.

[wbt]

Might be related to #2175 and/or #981/#982