The answer from @WanChap was good, but not when there is multiple file transports. I will post my entire logging solution below, which handles exiting the process correctly, including support for Development and Production.
The only caveat is that it does not work with the exceptions log at the moment, but it will work with every other transport based log. If anyone figures out how to make this work with the exception log as well, please post in the comments.
First, you want to create a folder in the same directory that your file that is doing the logs is in, and call it logger. In this folder, create three .js files, one called dev-logger.js, the other prod-logger.js, and finally index.js
In node, when you require a directory, it will assume you want to load the index.js file.
TheFileYouWantToLogFrom.js
const logger = require('./logger');
logger.info("it works!");
index.js
This file will look at your node process environment state and use the correct logger.
const buildDevLogger = require('./dev-logger');
const buildProdLogger = require('./prod-logger');
let logger = null;
if(process.env.NODE_ENV === 'development'){
logger = buildDevLogger();
}else{
logger = buildProdLogger();
}
module.exports = logger;
You can test this later, by simply calling your node process (in my case cron.js) in your terminal, by saying something like NODE_ENV=production node cron.js or NODE_ENV=development node cron.js
dev-logger.js
const { format, createLogger, transports} = require('winston');
const { timestamp, combine, printf, errors } = format;
var numOpenTransports = 0;
function buildDevLogger(){
const logFormat = printf(({ level, message, timestamp, stack, durationMs }) => {
return `${timestamp} ${level}: ${stack || message}${durationMs ? " | "+durationMs+'ms' : ''}`;
});
//For info on the options go here.
//https://github.com/winstonjs/winston/blob/master/docs/transports.md
var options = {
console: {
handleExceptions: true,
level: 'debug',
format: combine(
format.colorize(),
timestamp({format: 'YYYY-MM-DD HH:mm:ss'}),
errors({stack: true}),
logFormat
),
},
combined: {
filename: 'logs/dev/combined.log',
maxsize: 10000000,
maxFiles: 10,
tailable:true,
format: combine(
timestamp({format: 'YYYY-MM-DD HH:mm:ss'}),
errors({stack: true}),
logFormat
),
},
error: {
filename: 'logs/dev/error.log',
level: 'error',
maxsize: 10000000,
maxFiles: 10,
tailable:true ,
format: combine(
timestamp({format: 'YYYY-MM-DD HH:mm:ss'}),
errors({stack: true}),
logFormat
),
},
exception : {
filename: 'logs/dev/exceptions.log',
maxsize: 10000000,
maxFiles: 10,
tailable:true,
format: combine(
timestamp({format: 'YYYY-MM-DD HH:mm:ss'}),
errors({stack: true}),
logFormat
),
}
};
function fileFinished(){
numOpenTransports--;
if(numOpenTransports==0){
process.exit(0);
}
}
var combinedFile = new transports.File(options.combined);
var errorFile = new transports.File(options.error);
var exceptionFile = new transports.File(options.exception);
combinedFile.on('open', () => { // wait until file._dest is ready
numOpenTransports++;
combinedFile._dest.on('finish', () => {
fileFinished();
});
});
errorFile.on('open', () => { // wait until file._dest is ready
numOpenTransports++;
errorFile._dest.on('finish', () => {
fileFinished();
});
});
return createLogger({
defaultMeta: {service:'cron-dev'},
transports: [
new transports.Console(options.console),
combinedFile,
errorFile,
],
exceptionHandlers: [
exceptionFile
]
});
}
module.exports = buildDevLogger;
prod-logger.js
const { format, createLogger, transports} = require('winston');
const { timestamp, combine, errors, json } = format;
var numOpenTransports = 0;
function buildProdLogger(){
var options = {
console: {
handleExceptions: true,
level: 'debug',
format: combine(
timestamp({format: 'YYYY-MM-DD HH:mm:ss'}),
errors({stack: true}),
json()
),
},
combined: {
filename: 'logs/prod/combined.log',
maxsize: 10000000,
maxFiles: 10,
tailable:true,
format: combine(
timestamp({format: 'YYYY-MM-DD HH:mm:ss'}),
errors({stack: true}),
json()
),
},
error: {
filename: 'logs/prod/error.log',
level: 'error',
maxsize: 10000000,
maxFiles: 10,
tailable:true ,
format: combine(
timestamp({format: 'YYYY-MM-DD HH:mm:ss'}),
errors({stack: true}),
json()
),
},
exception : {
filename: 'logs/prod/exceptions.log',
maxsize: 10000000,
maxFiles: 10,
tailable:true,
format: combine(
timestamp({format: 'YYYY-MM-DD HH:mm:ss'}),
errors({stack: true}),
json()
),
}
};
function fileFinished(){
numOpenTransports--;
if(numOpenTransports==0){
process.exit(0);
}
}
var combinedFile = new transports.File(options.combined);
var errorFile = new transports.File(options.error);
var exceptionFile = new transports.File(options.exception);
combinedFile.on('open', () => { // wait until file._dest is ready
numOpenTransports++;
combinedFile._dest.on('finish', () => {
fileFinished();
});
});
errorFile.on('open', () => { // wait until file._dest is ready
numOpenTransports++;
errorFile._dest.on('finish', () => {
fileFinished();
});
});
return createLogger({
defaultMeta: {service:'cron-prod'},
transports: [
new transports.Console(options.console),
combinedFile,
errorFile,
],
exceptionHandlers: [
exceptionFile
]
});
}
module.exports = buildProdLogger;
The way the dev and prod logger files work is by using the numOpenTransports variable to keep track of which 'files transports' are currently open, and once they are all closed, then, and only then, exit the process.
