express - Limit a request to one at a time - node.js

Question

I'm using express to build a API that should be used internally. One of the request trigger an heavy process on the server and should return a CSV out of that. This process might take more than 10 minutes.
To not overloading the server I want to restrict the call of this API and make it so that, since the process isn't terminated, we can't request the same URL again.
For this I tried to use express-rate-limit with the following configuration:
new RateLimit({
windowMs: 30 * 60 * 1000, // 30 minutes
max: 1,
delayMs: 0, // disabled
message: 'Their is already a running execution of the request. You must wait for it to be finished before starting a new one.',
handler: function handler(req, res) {
logger.log('max request achieved');
logger.log(res);
},
});
But it seems that the 'max request' is reached every time after exactly 2 mins even if I start only once. I suspect the browser to retry the request after 2 min if doesn't get any answer, is it possible?
I would like that this request doesn't have any retry-strategy and that the only way the max request is reached is by manually asking the server to execute this request 2 times in a row.
Thank's.
Edit
Here is my full code:
const app = express();
const port = process.env.API_PORT || 3000;
app.enable('trust proxy');
function haltOnTimedout(req, res, next) {
if (!req.timedout) { next(); }
}
app.use(timeout(30 * 60 * 1000)); // 30min
app.use(haltOnTimedout);
app.listen(port, () => {
logger.log(`Express server listening on port ${port}`);
});
// BILLING
const billingApiLimiter = new RateLimit({
windowMs: 30 * 60 * 1000, // 30 minutes
max: 1,
delayMs: 0, // disabled
message: 'Their is already a running execution of the request. You must wait for it to be finished before starting a new one.',
handler: function handler(req, res) {
logger.log('max request achieved');
},
});
app.use('/billing', billingApiLimiter);
app.use('/billing', BillingController);
And the code of my route:
router.get('/billableElements', async (request, response) => {
logger.log('Route [billableElements] called');
const { startDate } = request.query;
const { endDate } = request.query;
try {
const configDoc = await metadataBucket.getAsync(process.env.BILLING_CONFIG_FILE || 'CONFIG_BILLING');
const billableElements = await getBillableElements(startDate, endDate, configDoc.value);
const csv = await produceCSV(billableElements);
logger.log('csv produced');
response.status(200).send(`${csv}`);
} catch (err) {
logger.error('An error occured while getting billable elements.', err);
response.status(500).send('An internal error occured.');
}
});

Answer 1

I found the answer thank's to this GitHub issue: https://github.com/expressjs/express/issues/2512.
TLDR: I added request.connection.setTimeout(1000 * 60 * 30); to avoid firing the request every 2 minutes.
But considering the code I wrote inside my question, #Paul's advices are still good to be taken into account.