I'm using node.js and express to handle HTTP requests and responses. By using the http.ServerRequest event, I can add a hook in and log HTTP requests. There doesn't seem to be a similiar event for http.ServerResponse and I am wondering how to log all the HTTP responses with one piece of code that my server sends?
4 Answers
I created a package that does such a thing, out of a similar need. Check out express-request-logger
The heart of the program is like this, it contains some extra code so you can have your own key-value map of data that gets logged per request:
// Save the real end that we will wrap
var rEnd = res.end;
// To track response time
req._rlStartTime = new Date();
// Proxy the real end function
res.end = function(chunk, encoding) {
// Do the work expected
res.end = rEnd;
res.end(chunk, encoding);
// And do the work we want now (logging!)
// Save a few more variables that we can only get at the end
req.kvLog.status = res.statusCode;
req.kvLog.response_time = (new Date() - req._rlStartTime);
// Send the log off to winston
var level = req.kvLog._rlLevel;
delete req.kvLog._rlLevel;
logger.log(level, '', req.kvLog);
};
The above code runs as middleware in express. Take a look at the code, and if you have further questions, get in touch with me on here or github.
2 Comments
rich remer
In current versions of Node.js,
res should generate a "finish" event which you can use instead of proxying the end method.
Gilad Dahan
I get: TypeError: winston.loggers is not a constructor
It is no longer needed to monkeypatch, as long as there is a finish event emitted on end() function since node.js 0.8.12.
Actually, it was initially published as end in 0.8.8 (check also this) but it broke writable streams' duplexes, so it was renamed to finish.
3 Comments
jakub.g
I've checked in Node 0.8.14 and 0.8.23 and
end is emitted, not finish. The commits you've linked are included in 0.9 / 0.10 branches (it's now being displayed by GH below the commit message since a couple of weeks ago).
Diogo Cardoso
Is is possible to get the response message on the finish event?
If you only want to log (requests and/or responses), check out express-winston. Unlike morgan, it can even log the request/response body.
Example in coffeescript:
expressWinston.requestWhitelist.push('body')
expressWinston.responseWhitelist.push('body')
app.use(expressWinston.logger({
transports: [
new winston.transports.Console({
json: true,
colorize: true
})
],
meta: true, // optional: control whether you want to log the meta data about the request (default to true)
msg: "HTTP {{req.method}} {{req.url}}", // optional: customize the default logging message. E.g. "{{res.statusCode}} {{req.method}} {{res.responseTime}}ms {{req.url}}"
expressFormat: true, // Use the default Express/morgan request formatting, with the same colors. Enabling this will override any msg and colorStatus if true. Will only output colors on transports with colorize set to true
colorStatus: true, // Color the status code, using the Express/morgan color palette (default green, 3XX cyan, 4XX yellow, 5XX red). Will not be recognized if expressFormat is true
ignoreRoute: function (req, res) { return false; } // optional: allows to skip some log messages based on request and/or response
}));
1 Comment
Edmond Meinfelder
This is the modern and perhaps most correct answer for today.
If you're using express' res.send() for all responses, and you don't mind inserting code into the express module, you can insert into
.../node_modules/express/lib/response.js:
43 res.send = function(body, headers, status){
44 console.log("\n...your log text here..." + body);
45 // allow status as second arg
46 if ('number' == typeof headers) {
47 status = headers,
48 headers = null;
49 }
I don't think you can listen for a non-error event - "close" doesn't seem to fire upon res.send();. I guess it's because send() is always called somewhere in your code.
1 Comment
Eric Elliott
This is a bad idea. See the other answers, instead.
"request"is emitted byHttpServerwhich express extends. The easiest way would be to overwrite.sendor.endwith a thin logging proxy.