Expressjs stream file with fetch to backend service-CodePudding

I have made an endpoint in my expressJs application, which should be able to proxy a large raw binary to a remote backend rest service, without saving anything to memory.

I can see that this relatively easily can be accomplished with request, by doing something like this:

req.pipe(request({method: "POST"}))

However, since the request library is deprecated, I want to use fetch instead. Thus far, I have come up with something as follows:

app.post("/my-endpoint", async (req, res) => {
    try {
        const url = http://link-to-backend.com/

        const request = await fetch(url, {
            method: "POST",
            body: req.body
        });
        request.body.pipe(res);
    } catch (e) {
        res.status(500).send("error");
    }
});

Above works as expected. However based on above, I would like to know if my approach actually saves req.body into memory before proxying the request to the backend api, and how I effectively can validate if it does/doesn't.

CodePudding user response：

The following middlewares passes the request and response bodies through chunk by chunk, without storing them entirely in memory:

app.post("/my-endpoint", async (req, res, next) => {
  delete req.headers.host; // you may want to delete certain cookies as well
  req.pipe(http.request(url, {
    method: "POST",
    headers: req.headers
  }).on("response", function(r) {
    res.writeHead(r.statusCode, r.statusMessage, r.headers);
    r.pipe(res);
  }).on("error", next));
});