express-winston-middleware

Winston log wrappers for Express.

Winston Middleware for Express

Winston log wrappers and middleware for Express.

You can install express-winston-middleware using NPM:

$ npm install express-winston-middleware

From there, you can create a Log instance or use the request Express middleware.

The Log logger class internally creates and wraps a Winston logger. You can create one with:

var winston = require("winston");
var Log = require("express-winston-middleware").Log;
 
// Create logger with Console transport and "foo" metadata item. 
var log = new Log({
  transports: [
    new (winston.transports.Console)({ json: true })
  ]
}, {
  // Metadata to add to each log response. 
  foo: "bar"
});
 
// Log something. 
log.info("Hello World!");

which produces the following output:

{
  "date": "2013-12-01T23:29:48.035Z",
  "env": "development",
  "server": {
    "id": "m",
    "pid": 24638,
    "hostName": "titan.local"
  },
  "foo": "bar",
  "level": "info",
  "message": "Hello World!"
}

The request middleware is added to your Express setup like:

var express = require("express");
var app = express(),
var requestLogger = require("express-winston-middleware").request;
 
/* ... */
 
// Same options and meta as for the `Log` class. 
app.use(logging.createMiddle(requestLogger({
  transports: [
    new (winston.transports.Console)({ json: true })
  ]
}, {
  // Metadata to add to each log response. 
  foo: "bar"
})));
 

and produces output for requests like:

{
  "date": "2013-12-01T23:32:54.759Z",
  "server": {
    "id": "m",
    "pid": 24653,
    "hostName": "titan.local"
  },
  "req": {
    "method": "GET",
    "host": "localhost:2000",
    "path": "/",
    "query": ""
  },
  "res": {
    "statusCode": 304
  },
  "foo": "bar",
  "level": "info",
  "message": "request"
}

The middleware attaches a logger to the response locals, available as res.locals._log, so that in addition to automatic request logging messages you can log extra messages with all of the current request metadata. E.g.:

app.get("/foo", function (reqres) {
  res.locals._log.info("This is an extra manual log message!", {
    extra: "metadata"
  });
  // Rest of your code here... 
});

Creates a middleware function using base metadata. Integration:

app.use(winMid.request({
  transports: [ new (winston.transports.Console)({ json: true }) ]
}, { foo: "bar" }));

Once integrated, a logger will be attached to the response locals, and available as res.locals._log.

Creates a middleware function for Express. Integration:

app.use(winMid.error({
  transports: [ new (winston.transports.Console)({ json: true }) ]
}, { foo: "bar" }));

Creates a handler function for any uncaught exception. Integration:

process.on("uncaughtException", winMid.uncaught({
  transports: [ new (winston.transports.Console)({ json: true }) ]
}, { foo: "bar" }));

Note: Terminates process at end.

Wraps Winston logger with additional functionality.

var log = new winMid.Log({
  transports: [ new (winston.transports.Console)({ json: true }) ]
}, { foo: "bar" }));

Add arbitrary meta to all subsequent log statements.

Add request to meta.

Add response to meta.

Add error to meta.

Please see the Contributions Guide for how to help out with the plugin.

We test all changes with Travis CI. Here's our current build status:

All code is Copyright 2013 Ryan Roemer. Released under the MIT License.