fix(converters): Ensure x-forwarded-proto is set to http when running locally

Author: sommeeeer

packages/open-next/src/overrides/converters/edge.ts

@@ -35,6 +35,11 @@ const converter: Converter<InternalEvent, InternalResult | MiddlewareResult> = {
       ),
     );
 
+    // This is to make libraries (i.e next-auth) that rely on this header to work out of the box in `opennextjs-cloudflare preview`.
+    if (url.protocol.slice(0, -1) === "http" && url.hostname === "localhost") {
+      headers["x-forwarded-proto"] = "http";
+    }
+
     return {
       type: "core",
       method,

packages/open-next/src/overrides/converters/node.ts

@@ -30,6 +30,14 @@ const converter: Converter = {
       `${req.protocol ? req.protocol : "http"}://${extractHostFromHeaders(headers)}${req.url}`,
     );
     const query = getQueryFromSearchParams(url.searchParams);
+
+    if (req.protocol === "http" && url.hostname === "localhost") {
+      // This is used internally by Next.js during redirects in server actions. We need to set it to the origin of the request.
+      process.env.__NEXT_PRIVATE_ORIGIN = url.origin;
+      // This is to make `next-auth` and other libraries that rely on this header to work locally out of the box.
+      headers["x-forwarded-proto"] = req.protocol;
+    }
+
     return {
       type: "core",
       method: req.method ?? "GET",