CODEWITHSUNDEEP
node.jsexpress
Edmond Meinfelder
Edmond Meinfelder

Reputation: 313

Adding a hook to globally log all node HTTP responses in node.js / express

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?

Upvotes: 10

Views: 15189

Answers (4)

Manuel Darveau
Manuel Darveau

Reputation: 4635

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
    }));

Upvotes: 3

Dario Castañé
Dario Castañé

Reputation: 1933

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.

Upvotes: 10

staackuser2
staackuser2

Reputation: 12412

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.

Upvotes: 10

Ray
Ray

Reputation: 370

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.

Upvotes: -6

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