Is it possible to define a unique request Id that is included in each log statement without handing the logger to each method/function call?
Technologies in use: NodeJS, Express, Winston
Edited
Finally, I have created a library that makes all the work. https://github.com/davicente/express-logger-unique-req-id
It is a wrapper of Winston library, so you can use it the same way.
Let me know if it helps you
We had this same problem in several projects, and I couldn't finde any complete solution for this question. We are using same technologies (Node.js, Express.js and Winston for logs) I found a solution to this using a couple of libraries and wrapping Winston library: - node-uuid for creating unique identificators for each request - continuation-local-storage for sharing this IDs among different modules without sending req object in all the calls.
First I need to create and set the unique identificator with each request. I do it in the middleware:
var uuid = require('node-uuid');
var createNamespace = require('continuation-local-storage').createNamespace;
var myRequest = createNamespace('my request');
// Run the context for each request. Assign a unique identifier to each request
app.use(function(req, res, next) {
myRequest.run(function() {
myRequest.set('reqId', uuid.v1());
next();
});
});
After that I had to wrap Winston library, recovering the id from the context and adding to the message of the log:
var winston = require('winston');
var getNamespace = require('continuation-local-storage').getNamespace;
// Wrap Winston logger to print reqId in each log
var formatMessage = function(message) {
var myRequest = getNamespace('my request');
message = myRequest && myRequest.get('reqId') ? message + " reqId: " + myRequest.get('reqId') : message;
return message;
};
var logger = {
log: function(level, message) {
winstonLogger.log(level, formatMessage(message));
},
error: function(message) {
winstonLogger.error(formatMessage(message));
},
warn: function(message) {
winstonLogger.warn(formatMessage(message));
},
verbose: function(message) {
winstonLogger.verbose(formatMessage(message));
},
info: function(message) {
winstonLogger.info(formatMessage(message));
},
debug: function(message) {
winstonLogger.debug(formatMessage(message));
},
silly: function(message) {
winstonLogger.silly(formatMessage(message));
}
};
module.exports = logger;
I think it was a little bit complex, so I decided to write it down in a post. You can get more information from there: Express.js: Logging info with global unique request ID – Node.js
I hope this helps with your problem.