Express.js connect timeout vs server timeout

Question

I am using express and Connect Timeout Middleware to handle the timeouts.

It works great, but I the default node http server's timeout is set to two minutes.

Therefore if I want to set my timeout middleware to a value greater than two minutes, I also have to increase the http server timeout to be slightly bigger (otherwise my connect timeout handler is not called)

const app = express();
const http = new Http.Server(app);

http.setTimeout((4 * 60 * 1000) + 1); <-- Must set this

app.use(timeout('4m')); 

How can I avoid this ? Am I missing something ?

Answer 1

If you want to use the connect-timeout middleware, you can't avoid it, since the middleware does not change the socket timeout, which defaults to 2 minutes.

There are two possible ways to avoid it, either using server.setTimeout() or request.setTimeout.

In case you only want to change the timeout to a few routes, and leave the default timeout to the rest, the recommended approach is to use: request.setTimeout

app.use('/some-routes', (req, res, next) => {
   req.setTimeout((4 * 60 * 1000) + 1);
   next();
}, timeout('4m'));

An alternative to setting the req.setTimeout to a value greater than the connect-timeout value, is dropping the connect-timeout middleware and using another work around, which is also not ideal.

You can check this old Node.js issue https://github.com/nodejs/node-v0.x-archive/issues/3460

function haltOnTimedout (req, res, next) {
  if (!req.timedout) next()
}

app.use('/some-routes', (req, res, next) => {
    req.setTimeout(4 * 60 * 1000); // No need to offset

    req.socket.removeAllListeners('timeout'); // This is the work around
    req.socket.once('timeout', () => {
        req.timedout = true;
        res.status(504).send('Timeout');
    });

    next();
});


app.use(haltOnTimedout);

// But if the timeout occurs in the middle of a route
// You will need to check if the headers were sent or if the request timedout

app.get('/some-routes', async(req, res, next) => {
  
  // some async processing...
  await asyncOperation();
  
  if (!res.headersSent) // or !req.timedout 
    res.send('done');
 
});