Expose socket-level stats in response

[daniil-poletaev]

We're migrating from got-scraping to impit in proxy. One thing we're currently unable to replace is the socket-level data transfer stats that got-scraping exposed via response.request.socket:

response = await gotScraping.get(...);
const { body, statusCode } = response;

// Compute data transfer stats
// We store the previous bytes due to the fact that sockets can be reused
const { socket } = response.request as {
   socket: Socket & {
      prevBytesRead?: number;
      prevBytesWritten?: number;
   };
};
const socketBytesRead = socket.bytesRead;
const socketBytesWritten = socket.bytesWritten;
this._incrementStats(connectionId, {
   [providerId]: {
      recvBytes: socketBytesRead - (socket.prevBytesRead || 0),
      sentBytes: socketBytesWritten - (socket.prevBytesWritten || 0),
   },
});

Can we expose socket stats in Impit as well?

[barjin]

We looked into this. The byte counting itself is easy to add in our hyper-util fork, but getting those stats propagated to the response for HTTPS connections would require also patching reqwest — its internal TLS connection handling bypasses the metadata path we'd need.

We already maintain patches for hyper-util, h2, rustls, and tower-http. Adding reqwest to that list is a significant maintenance burden we'd like to avoid if possible.

We'll keep this open and revisit if a cleaner approach becomes available upstream.

[daniil-poletaev]

Makes sense, thank you for quick feedback!

We'll do it on our side 😉