Uploading a file through an Express pass-through endoint

[dglozic]

I am trying to port an endpoint from Express that uses request module. The endpoint is used to upload a picture file from the browser. The Express endpoint serves as a pass-through proxy, sending the POST request into the downstream API where the picture is stored.

I am not clear if I should use Undici.request, stream or pipeline for this, and how exactly. Something like:

router.port("/upload", (req, res) => {
   const undiciOptions = {
      url: "https://api.acme.com/upload",
      method: "post",
      headers: req.headers
   };
   undiciOptions.headers.authorization = `bearer ${req.user.accessToken}`;
   // NOW: which function from Undici should be used to stream the incoming multi-part form into the 
   // downstream API defined by undiciOptions?
});

[dglozic]

Any takers?

[dglozic]

Actually I think I fixed it. It looks like if I provide Express request as the 'body' in undiciOptions, this works fine as stream will treat this as a Readable:

		body: Readable.toWeb(options.request),

Another requirement is to provide a new dispatcher with strictContentLength: false passed into the Agent constructor. With these two changes, I can stream multipart file uploads using stream into the ultimate destination.