node.js - How to determine http vs https in nodejs / nextjs api handler

Question

In order to properly build my urls in my xml sitemaps and rss feeds I want to determine if the webpage is currently served over http or https, so it also works locally in development.

export default function handler(req, res) {
  const host = req.headers.host;
  const proto = req.connection.encrypted ? "https" : "http";

  //construct url for xml sitemaps
}

With above code however also on Vercel it still shows as being served over http. I would expect it to run as https. Is there a better way to figure out http vs https?

question from:https://stackoverflow.com/questions/65871390/how-to-determine-http-vs-https-in-nodejs-nextjs-api-handler

Answer 1

As Next.js api routes run behind a proxy which is offloading to http the protocol is http.

By changing the code to the following I was able to first check at what protocol the proxy runs.

  const proto = req.headers["x-forwarded-proto"];

However this will break the thing in development where you are not running behind a proxy, or a different way of deploying the solution that might also not involve a proxy. To support both use cases I eventually ended up with the following code.

  const proto =
    req.headers["x-forwarded-proto"] || req.connection.encrypted
      ? "https"
      : "http";

Whenever the x-forwarded-proto header is not present (undefined) we fall back to req.connection.encrypted to determine if we should serve on http vs https.

Now it works on localhost as well a Vercel deployment.