Traveling Tech Guy Traveling Tech Guy - 1 year ago 107
Node.js Question

Adding timestamps to all console messages

I have a complete, deployed, Express-based project, with many console.log() and console.error() statements throughout.
The project runs using forever, directing the stdout and stderr to 2 separate files.

It all works quite well, but now I'm missing timestamps - to know exactly when errors occurred.

I can do some kind of search/replace throughout my code, or use some npm module that overrides console in each file, but I do not want to touch every model/route file, unless I absolutely have to.

Is there a way, perhaps an Express middleware, that would allow me to add a timestamp to every call made, or do I have to manually add it?

Answer Source

It turns out, you can override the console functions at the top of the app.js file, and have it take effect in every other module. I got mixed results because one of my modules is forked as a child_process. Once I copied the line to the top of that file as well, all works.

For the record, I installed the module console-stamp (npm install console-stamp --save), and added this line to the top of app.js and childProcess.js:

// add timestamps in front of log messages
require('console-stamp')(console, '[HH:MM:ss.l]');

My problem now was that the :date format of the connect logger uses UTC format, rather than the one I'm using in the other console calls. That was easily fixed by registering my own time format (and as a side effect, requiring the dateformat module that console stamp comes with, rather than installing another one):

// since logger only returns a UTC version of date, I'm defining my own date format - using an internal module from console-stamp
express.logger.format('mydate', function() {
    var df = require('console-stamp/node_modules/dateformat');
    return df(new Date(), 'HH:MM:ss.l');
app.use(express.logger('[:mydate] :method :url :status :res[content-length] - :remote-addr - :response-time ms'));

Now my log files look organized (and better yet, parseable):

[15:09:47.746] staging server listening on port 3000
[15:09:49.322] connected to database server xxxxx successfully
[15:09:52.743] GET /product 200 - - - 214 ms
[15:09:52.929] GET /stylesheets/bootstrap-cerulean.min.css 304 - - - 8 ms
[15:09:52.935] GET /javascripts/vendor/require.js 304 - - - 3 ms
[15:09:53.085] GET /javascripts/product.js 304 - - - 2 ms