From 5ecfc3ed4401d6ee10f403c40420c61e96999f9a Mon Sep 17 00:00:00 2001
From: Dorseuil Nicolas <nicodorseuil@yahoo.fr>
Date: Thu, 14 Nov 2024 12:51:59 +0100
Subject: [PATCH 01/12] proxyRequest is now an override

---
 packages/open-next/src/adapters/middleware.ts | 20 +++--
 .../open-next/src/build/createMiddleware.ts   |  5 +-
 .../src/build/edge/createEdgeBundle.ts        |  9 +-
 .../open-next/src/core/createMainHandler.ts   |  5 ++
 packages/open-next/src/core/requestHandler.ts | 29 +++----
 packages/open-next/src/core/resolve.ts        | 17 ++++
 packages/open-next/src/core/routing/util.ts   | 82 ------------------
 .../overrides/converters/aws-cloudfront.ts    | 22 +----
 .../overrides/proxyExternalRequest/dummy.ts   | 10 +++
 .../overrides/proxyExternalRequest/fetch.ts   | 28 +++++++
 .../overrides/proxyExternalRequest/node.ts    | 83 +++++++++++++++++++
 packages/open-next/src/plugins/resolve.ts     | 13 ++-
 packages/open-next/src/types/global.ts        | 14 +++-
 packages/open-next/src/types/open-next.ts     | 11 +++
 packages/open-next/src/types/overrides.ts     |  4 +
 15 files changed, 222 insertions(+), 130 deletions(-)
 create mode 100644 packages/open-next/src/overrides/proxyExternalRequest/dummy.ts
 create mode 100644 packages/open-next/src/overrides/proxyExternalRequest/fetch.ts
 create mode 100644 packages/open-next/src/overrides/proxyExternalRequest/node.ts

diff --git a/packages/open-next/src/adapters/middleware.ts b/packages/open-next/src/adapters/middleware.ts
index 5ae66951..634f581c 100644
--- a/packages/open-next/src/adapters/middleware.ts
+++ b/packages/open-next/src/adapters/middleware.ts
@@ -6,6 +6,7 @@ import { createGenericHandler } from "../core/createGenericHandler";
 import {
   resolveIncrementalCache,
   resolveOriginResolver,
+  resolveProxyRequest,
   resolveQueue,
   resolveTagCache,
 } from "../core/resolve";
@@ -19,6 +20,10 @@ const defaultHandler = async (internalEvent: InternalEvent) => {
     globalThis.openNextConfig.middleware?.originResolver,
   );
 
+  const externalRequestProxy = await resolveProxyRequest(
+    globalThis.openNextConfig.middleware?.override?.proxyExternalRequest,
+  );
+
   //#override includeCacheInMiddleware
   globalThis.tagCache = await resolveTagCache(
     globalThis.openNextConfig.middleware?.override?.tagCache,
@@ -43,14 +48,15 @@ const defaultHandler = async (internalEvent: InternalEvent) => {
         let origin: Origin | false = false;
         if (!result.isExternalRewrite) {
           origin = await originResolver.resolve(result.internalEvent.rawPath);
+          return {
+            type: "middleware",
+            internalEvent: result.internalEvent,
+            isExternalRewrite: result.isExternalRewrite,
+            origin,
+            isISR: result.isISR,
+          };
         }
-        return {
-          type: "middleware",
-          internalEvent: result.internalEvent,
-          isExternalRewrite: result.isExternalRewrite,
-          origin,
-          isISR: result.isISR,
-        };
+        return externalRequestProxy.proxy(result.internalEvent);
       }
 
       debug("Middleware response", result);
diff --git a/packages/open-next/src/build/createMiddleware.ts b/packages/open-next/src/build/createMiddleware.ts
index f74b8ac2..13a957ce 100644
--- a/packages/open-next/src/build/createMiddleware.ts
+++ b/packages/open-next/src/build/createMiddleware.ts
@@ -57,7 +57,10 @@ export async function createMiddleware(
       outfile: path.join(outputPath, "handler.mjs"),
       middlewareInfo,
       options,
-      overrides: config.middleware?.override,
+      overrides: {
+        ...config.middleware.override,
+        originResolver: config.middleware.originResolver,
+      },
       defaultConverter: "aws-cloudfront",
       includeCache: config.dangerous?.enableCacheInterception,
       additionalExternals: config.edgeExternals,
diff --git a/packages/open-next/src/build/edge/createEdgeBundle.ts b/packages/open-next/src/build/edge/createEdgeBundle.ts
index 66a796db..d2bbd86a 100644
--- a/packages/open-next/src/build/edge/createEdgeBundle.ts
+++ b/packages/open-next/src/build/edge/createEdgeBundle.ts
@@ -6,11 +6,14 @@ import { build } from "esbuild";
 import type { MiddlewareInfo, MiddlewareManifest } from "types/next-types";
 import type {
   IncludedConverter,
+  IncludedOriginResolver,
+  LazyLoadedOverride,
   OverrideOptions,
   RouteTemplate,
   SplittedFunctionOptions,
 } from "types/open-next";
 
+import type { OriginResolver } from "types/overrides.js";
 import logger from "../../logger.js";
 import { openNextEdgePlugins } from "../../plugins/edge.js";
 import { openNextReplacementPlugin } from "../../plugins/replacement.js";
@@ -23,7 +26,11 @@ interface BuildEdgeBundleOptions {
   entrypoint: string;
   outfile: string;
   options: BuildOptions;
-  overrides?: OverrideOptions;
+  overrides?: OverrideOptions & {
+    originResolver?:
+      | LazyLoadedOverride<OriginResolver>
+      | IncludedOriginResolver;
+  };
   defaultConverter?: IncludedConverter;
   additionalInject?: string;
   includeCache?: boolean;
diff --git a/packages/open-next/src/core/createMainHandler.ts b/packages/open-next/src/core/createMainHandler.ts
index 3c96d7f7..72d26f47 100644
--- a/packages/open-next/src/core/createMainHandler.ts
+++ b/packages/open-next/src/core/createMainHandler.ts
@@ -6,6 +6,7 @@ import { openNextHandler } from "./requestHandler";
 import {
   resolveConverter,
   resolveIncrementalCache,
+  resolveProxyRequest,
   resolveQueue,
   resolveTagCache,
   resolveWrapper,
@@ -33,6 +34,10 @@ export async function createMainHandler() {
 
   globalThis.tagCache = await resolveTagCache(thisFunction.override?.tagCache);
 
+  globalThis.proxyExternalRequest = await resolveProxyRequest(
+    thisFunction.override?.proxyExternalRequest,
+  );
+
   globalThis.lastModified = {};
 
   // From the config, we create the converter
diff --git a/packages/open-next/src/core/requestHandler.ts b/packages/open-next/src/core/requestHandler.ts
index ffce1038..0b5f5750 100644
--- a/packages/open-next/src/core/requestHandler.ts
+++ b/packages/open-next/src/core/requestHandler.ts
@@ -7,7 +7,8 @@ import { runWithOpenNextRequestContext } from "utils/promise";
 
 import { debug, error, warn } from "../adapters/logger";
 import { patchAsyncStorage } from "./patchAsyncStorage";
-import { convertRes, createServerResponse, proxyRequest } from "./routing/util";
+import { resolveProxyRequest } from "./resolve";
+import { convertRes, createServerResponse } from "./routing/util";
 import type { MiddlewareOutputEvent } from "./routingHandler";
 import routingHandler, {
   MIDDLEWARE_HEADER_PREFIX,
@@ -65,6 +66,16 @@ export async function openNextHandler(
         delete headers[rawKey];
       }
 
+      if (
+        "isExternalRewrite" in preprocessResult &&
+        preprocessResult.isExternalRewrite
+      ) {
+        const proxyResult = await globalThis.proxyExternalRequest.proxy(
+          preprocessResult.internalEvent,
+        );
+        preprocessResult = proxyResult;
+      }
+
       if ("type" in preprocessResult) {
         // response is used only in the streaming case
         if (responseStreaming) {
@@ -110,7 +121,6 @@ export async function openNextHandler(
         store.mergeHeadersPriority = mergeHeadersPriority;
       }
 
-      const preprocessedResult = preprocessResult as MiddlewareOutputEvent;
       const req = new IncomingMessage(reqProps);
       const res = createServerResponse(
         preprocessedEvent,
@@ -118,12 +128,7 @@ export async function openNextHandler(
         responseStreaming,
       );
 
-      await processRequest(
-        req,
-        res,
-        preprocessedEvent,
-        preprocessedResult.isExternalRewrite,
-      );
+      await processRequest(req, res, preprocessedEvent);
 
       const {
         statusCode,
@@ -155,7 +160,6 @@ async function processRequest(
   req: IncomingMessage,
   res: OpenNextNodeResponse,
   internalEvent: InternalEvent,
-  isExternalRewrite?: boolean,
 ) {
   // @ts-ignore
   // Next.js doesn't parse body if the property exists
@@ -163,13 +167,6 @@ async function processRequest(
   delete req.body;
 
   try {
-    // `serverHandler` is replaced at build time depending on user's
-    // nextjs version to patch Nextjs 13.4.x and future breaking changes.
-
-    if (isExternalRewrite) {
-      return proxyRequest(internalEvent, res);
-    }
-
     //#override applyNextjsPrebundledReact
     setNextjsPrebundledReact(internalEvent.rawPath);
     //#endOverride
diff --git a/packages/open-next/src/core/resolve.ts b/packages/open-next/src/core/resolve.ts
index d31edfc3..e6cede42 100644
--- a/packages/open-next/src/core/resolve.ts
+++ b/packages/open-next/src/core/resolve.ts
@@ -1,6 +1,7 @@
 import type {
   BaseEventOrResult,
   DefaultOverrideOptions,
+  IncludedProxyExternalRequest,
   InternalEvent,
   InternalResult,
   LazyLoadedOverride,
@@ -10,6 +11,7 @@ import type {
   Converter,
   ImageLoader,
   OriginResolver,
+  ProxyExternalRequest,
   TagCache,
   Warmer,
   Wrapper,
@@ -130,3 +132,18 @@ export async function resolveWarmerInvoke(
   const m_1 = await import("../overrides/warmer/aws-lambda.js");
   return m_1.default;
 }
+
+/**
+ * @__PURE__
+ */
+export async function resolveProxyRequest(
+  proxyRequest?:
+    | LazyLoadedOverride<ProxyExternalRequest>
+    | IncludedProxyExternalRequest,
+) {
+  if (typeof proxyRequest === "function") {
+    return proxyRequest();
+  }
+  const m_1 = await import("../overrides/proxyExternalRequest/node.js");
+  return m_1.default;
+}
diff --git a/packages/open-next/src/core/routing/util.ts b/packages/open-next/src/core/routing/util.ts
index db5a9ba5..cba325f1 100644
--- a/packages/open-next/src/core/routing/util.ts
+++ b/packages/open-next/src/core/routing/util.ts
@@ -164,33 +164,6 @@ export function unescapeRegex(str: string) {
     .replaceAll("_µ3_", "(...)");
 }
 
-/**
- *
- * @__PURE__
- */
-function filterHeadersForProxy(
-  headers: Record<string, string | string[] | undefined>,
-) {
-  const filteredHeaders: Record<string, string | string[]> = {};
-  const disallowedHeaders = [
-    "host",
-    "connection",
-    "via",
-    "x-cache",
-    "transfer-encoding",
-    "content-encoding",
-    "content-length",
-  ];
-  Object.entries(headers).forEach(([key, value]) => {
-    const lowerKey = key.toLowerCase();
-    if (disallowedHeaders.includes(lowerKey) || lowerKey.startsWith("x-amz"))
-      return;
-
-    filteredHeaders[key] = value?.toString() ?? "";
-  });
-  return filteredHeaders;
-}
-
 /**
  * @__PURE__
  */
@@ -209,61 +182,6 @@ export function convertBodyToReadableStream(
   return readable;
 }
 
-/**
- *
- * @__PURE__
- */
-export async function proxyRequest(
-  internalEvent: InternalEvent,
-  res: OpenNextNodeResponse,
-) {
-  const { url, headers, method, body } = internalEvent;
-  const request = await import("node:https").then((m) => m.request);
-  debug("proxyRequest", url);
-  await new Promise<void>((resolve, reject) => {
-    const filteredHeaders = filterHeadersForProxy(headers);
-    debug("filteredHeaders", filteredHeaders);
-    const req = request(
-      url,
-      {
-        headers: filteredHeaders,
-        method,
-        rejectUnauthorized: false,
-      },
-      (_res) => {
-        res.writeHead(
-          _res.statusCode ?? 200,
-          filterHeadersForProxy(_res.headers),
-        );
-        if (_res.headers["content-encoding"] === "br") {
-          _res.pipe(require("node:zlib").createBrotliDecompress()).pipe(res);
-        } else if (_res.headers["content-encoding"] === "gzip") {
-          _res.pipe(require("node:zlib").createGunzip()).pipe(res);
-        } else {
-          _res.pipe(res);
-        }
-
-        _res.on("error", (e) => {
-          error("proxyRequest error", e);
-          res.end();
-          reject(e);
-        });
-        res.on("finish", () => {
-          resolve();
-        });
-      },
-    );
-
-    if (body && method !== "GET" && method !== "HEAD") {
-      req.write(body);
-    }
-    req.end();
-  });
-  // console.log("result", result);
-  // res.writeHead(result.status, resHeaders);
-  // res.end(await result.text());
-}
-
 enum CommonHeaders {
   CACHE_CONTROL = "cache-control",
   NEXT_CACHE = "x-nextjs-cache",
diff --git a/packages/open-next/src/overrides/converters/aws-cloudfront.ts b/packages/open-next/src/overrides/converters/aws-cloudfront.ts
index 3d60e53f..494cd84d 100644
--- a/packages/open-next/src/overrides/converters/aws-cloudfront.ts
+++ b/packages/open-next/src/overrides/converters/aws-cloudfront.ts
@@ -18,7 +18,6 @@ import {
   convertToQuery,
   convertToQueryString,
   createServerResponse,
-  proxyRequest,
 } from "../../core/routing/util";
 import type { MiddlewareOutputEvent } from "../../core/routingHandler";
 
@@ -159,26 +158,7 @@ async function convertToCloudFrontRequestResult(
     const responseHeaders = result.internalEvent.headers;
 
     // Handle external rewrite
-    if (result.isExternalRewrite) {
-      const serverResponse = createServerResponse(result.internalEvent, {});
-      await proxyRequest(result.internalEvent, serverResponse);
-      const externalResult = convertRes(serverResponse);
-      const body = await fromReadableStream(
-        externalResult.body,
-        externalResult.isBase64Encoded,
-      );
-      const cloudfrontResult = {
-        status: externalResult.statusCode.toString(),
-        statusDescription: "OK",
-        headers: convertToCloudfrontHeaders(externalResult.headers, true),
-        bodyEncoding: externalResult.isBase64Encoded
-          ? ("base64" as const)
-          : ("text" as const),
-        body,
-      };
-      debug("externalResult", cloudfrontResult);
-      return cloudfrontResult;
-    }
+
     let customOrigin = origin?.custom as CloudFrontCustomOrigin;
     let host = responseHeaders.host ?? responseHeaders.Host;
     if (result.origin) {
diff --git a/packages/open-next/src/overrides/proxyExternalRequest/dummy.ts b/packages/open-next/src/overrides/proxyExternalRequest/dummy.ts
new file mode 100644
index 00000000..0ef1b51d
--- /dev/null
+++ b/packages/open-next/src/overrides/proxyExternalRequest/dummy.ts
@@ -0,0 +1,10 @@
+import type { ProxyExternalRequest } from "types/overrides";
+
+const DummyProxyExternalRequest: ProxyExternalRequest = {
+  name: "dummy",
+  proxy: async (_event) => {
+    throw new Error("This is a dummy implementation");
+  },
+};
+
+export default DummyProxyExternalRequest;
diff --git a/packages/open-next/src/overrides/proxyExternalRequest/fetch.ts b/packages/open-next/src/overrides/proxyExternalRequest/fetch.ts
new file mode 100644
index 00000000..c10234da
--- /dev/null
+++ b/packages/open-next/src/overrides/proxyExternalRequest/fetch.ts
@@ -0,0 +1,28 @@
+import type { ProxyExternalRequest } from "types/overrides";
+import { emptyReadableStream } from "utils/stream";
+
+const fetchProxy: ProxyExternalRequest = {
+  name: "fetch-proxy",
+  // @ts-ignore
+  proxy: async (internalEvent) => {
+    const { url, headers, method, body } = internalEvent;
+    const response = await fetch(url, {
+      method,
+      headers,
+      body,
+    });
+    const responseHeaders: Record<string, string | string[]> = {};
+    response.headers.forEach((value, key) => {
+      responseHeaders[key] = value;
+    });
+    return {
+      type: "core",
+      headers: responseHeaders,
+      statusCode: response.status,
+      isBase64Encoded: true,
+      body: response.body ?? emptyReadableStream(),
+    };
+  },
+};
+
+export default fetchProxy;
diff --git a/packages/open-next/src/overrides/proxyExternalRequest/node.ts b/packages/open-next/src/overrides/proxyExternalRequest/node.ts
new file mode 100644
index 00000000..143b7600
--- /dev/null
+++ b/packages/open-next/src/overrides/proxyExternalRequest/node.ts
@@ -0,0 +1,83 @@
+import { debug, error } from "node:console";
+import { request } from "node:https";
+import { Readable } from "node:stream";
+import type { InternalEvent, InternalResult } from "types/open-next";
+import type { ProxyExternalRequest } from "types/overrides";
+import { isBinaryContentType } from "../../adapters/binary";
+
+function filterHeadersForProxy(
+  headers: Record<string, string | string[] | undefined>,
+) {
+  const filteredHeaders: Record<string, string | string[]> = {};
+  const disallowedHeaders = [
+    "host",
+    "connection",
+    "via",
+    "x-cache",
+    "transfer-encoding",
+    "content-encoding",
+    "content-length",
+  ];
+  Object.entries(headers).forEach(([key, value]) => {
+    const lowerKey = key.toLowerCase();
+    if (disallowedHeaders.includes(lowerKey) || lowerKey.startsWith("x-amz"))
+      return;
+
+    filteredHeaders[key] = value?.toString() ?? "";
+  });
+  return filteredHeaders;
+}
+
+const nodeProxy: ProxyExternalRequest = {
+  name: "node-proxy",
+  proxy: (internalEvent: InternalEvent) => {
+    const { url, headers, method, body } = internalEvent;
+    debug("proxyRequest", url);
+    return new Promise<InternalResult>((resolve, reject) => {
+      const filteredHeaders = filterHeadersForProxy(headers);
+      debug("filteredHeaders", filteredHeaders);
+      const req = request(
+        url,
+        {
+          headers: filteredHeaders,
+          method,
+          rejectUnauthorized: false,
+        },
+        (_res) => {
+          const nodeReadableStream =
+            _res.headers["content-encoding"] === "br"
+              ? _res.pipe(require("node:zlib").createBrotliDecompress())
+              : _res.headers["content-encoding"] === "gzip"
+                ? _res.pipe(require("node:zlib").createGunzip())
+                : _res;
+
+          const isBase64Encoded =
+            isBinaryContentType(headers["content-type"]) ||
+            !!headers["content-encoding"];
+          const result: InternalResult = {
+            type: "core",
+            headers: filterHeadersForProxy(_res.headers),
+            statusCode: _res.statusCode ?? 200,
+            // TODO: check base64 encoding
+            isBase64Encoded,
+            body: Readable.toWeb(nodeReadableStream),
+          };
+
+          resolve(result);
+
+          _res.on("error", (e) => {
+            error("proxyRequest error", e);
+            reject(e);
+          });
+        },
+      );
+
+      if (body && method !== "GET" && method !== "HEAD") {
+        req.write(body);
+      }
+      req.end();
+    });
+  },
+};
+
+export default nodeProxy;
diff --git a/packages/open-next/src/plugins/resolve.ts b/packages/open-next/src/plugins/resolve.ts
index a0ea01cc..44cf909f 100644
--- a/packages/open-next/src/plugins/resolve.ts
+++ b/packages/open-next/src/plugins/resolve.ts
@@ -6,11 +6,17 @@ import type {
   DefaultOverrideOptions,
   IncludedImageLoader,
   IncludedOriginResolver,
+  IncludedProxyExternalRequest,
   IncludedWarmer,
   LazyLoadedOverride,
   OverrideOptions,
 } from "types/open-next";
-import type { ImageLoader, OriginResolver, Warmer } from "types/overrides";
+import type {
+  ImageLoader,
+  OriginResolver,
+  ProxyExternalRequest,
+  Warmer,
+} from "types/overrides";
 
 import logger from "../logger.js";
 
@@ -26,6 +32,9 @@ export interface IPluginSettings {
       | LazyLoadedOverride<OriginResolver>
       | IncludedOriginResolver;
     warmer?: LazyLoadedOverride<Warmer> | IncludedWarmer;
+    proxyExternalRequest?:
+      | LazyLoadedOverride<ProxyExternalRequest>
+      | IncludedProxyExternalRequest;
   };
   fnName?: string;
 }
@@ -50,6 +59,7 @@ const nameToFolder = {
   imageLoader: "imageLoader",
   originResolver: "originResolver",
   warmer: "warmer",
+  proxyExternalRequest: "proxyExternalRequest",
 };
 
 const defaultOverrides = {
@@ -61,6 +71,7 @@ const defaultOverrides = {
   imageLoader: "s3",
   originResolver: "pattern-env",
   warmer: "aws-lambda",
+  proxyExternalRequest: "node",
 };
 
 /**
diff --git a/packages/open-next/src/types/global.ts b/packages/open-next/src/types/global.ts
index 2f9191a3..033802a5 100644
--- a/packages/open-next/src/types/global.ts
+++ b/packages/open-next/src/types/global.ts
@@ -1,7 +1,12 @@
 import type { AsyncLocalStorage } from "node:async_hooks";
 import type { OutgoingHttpHeaders } from "node:http";
 
-import type { IncrementalCache, Queue, TagCache } from "types/overrides";
+import type {
+  IncrementalCache,
+  ProxyExternalRequest,
+  Queue,
+  TagCache,
+} from "types/overrides";
 
 import type { DetachedPromiseRunner } from "../utils/promise";
 import type { OpenNextConfig } from "./open-next";
@@ -194,4 +199,11 @@ declare global {
    * Defined in `createMainHandler` or in `adapter/middleware.ts`.
    */
   var queue: Queue;
+
+  /**
+   * The function that is used when resolving external rewrite requests.
+   * Only available in main functions
+   * Defined in `createMainHandler`.
+   */
+  var proxyExternalRequest: ProxyExternalRequest;
 }
diff --git a/packages/open-next/src/types/open-next.ts b/packages/open-next/src/types/open-next.ts
index bd975584..bfa16804 100644
--- a/packages/open-next/src/types/open-next.ts
+++ b/packages/open-next/src/types/open-next.ts
@@ -6,6 +6,7 @@ import type {
   ImageLoader,
   IncrementalCache,
   OriginResolver,
+  ProxyExternalRequest,
   Queue,
   TagCache,
   Warmer,
@@ -102,6 +103,8 @@ export type IncludedOriginResolver = "pattern-env";
 
 export type IncludedWarmer = "aws-lambda";
 
+export type IncludedProxyExternalRequest = "node" | "fetch";
+
 export interface DefaultOverrideOptions<
   E extends BaseEventOrResult = InternalEvent,
   R extends BaseEventOrResult = InternalResult,
@@ -145,6 +148,14 @@ export interface OverrideOptions extends DefaultOverrideOptions {
    * @default "sqs"
    */
   queue?: IncludedQueue | LazyLoadedOverride<Queue>;
+
+  /**
+   * Add possibility to override the default proxy for external rewrite
+   * @default "node"
+   */
+  proxyExternalRequest?:
+    | IncludedProxyExternalRequest
+    | LazyLoadedOverride<ProxyExternalRequest>;
 }
 
 export interface InstallOptions {
diff --git a/packages/open-next/src/types/overrides.ts b/packages/open-next/src/types/overrides.ts
index 74bc171d..b245b7b2 100644
--- a/packages/open-next/src/types/overrides.ts
+++ b/packages/open-next/src/types/overrides.ts
@@ -135,3 +135,7 @@ export type ImageLoader = BaseOverride & {
 export type OriginResolver = BaseOverride & {
   resolve: (path: string) => Promise<Origin | false>;
 };
+
+export type ProxyExternalRequest = BaseOverride & {
+  proxy: (event: InternalEvent) => Promise<InternalResult>;
+};

From 055d1a8f5b21077306f05e574be68240bb6948e5 Mon Sep 17 00:00:00 2001
From: Dorseuil Nicolas <nicodorseuil@yahoo.fr>
Date: Thu, 14 Nov 2024 13:01:01 +0100
Subject: [PATCH 02/12] handle errors in request handler

---
 packages/open-next/src/core/requestHandler.ts | 27 ++++++++++++++++---
 1 file changed, 23 insertions(+), 4 deletions(-)

diff --git a/packages/open-next/src/core/requestHandler.ts b/packages/open-next/src/core/requestHandler.ts
index 0b5f5750..aaacb2bd 100644
--- a/packages/open-next/src/core/requestHandler.ts
+++ b/packages/open-next/src/core/requestHandler.ts
@@ -70,10 +70,29 @@ export async function openNextHandler(
         "isExternalRewrite" in preprocessResult &&
         preprocessResult.isExternalRewrite
       ) {
-        const proxyResult = await globalThis.proxyExternalRequest.proxy(
-          preprocessResult.internalEvent,
-        );
-        preprocessResult = proxyResult;
+        try {
+          const proxyResult = await globalThis.proxyExternalRequest.proxy(
+            preprocessResult.internalEvent,
+          );
+          preprocessResult = proxyResult;
+        } catch (e) {
+          error("External request failed.", e);
+          preprocessResult = {
+            internalEvent: {
+              type: "core",
+              rawPath: "/500",
+              method: "GET",
+              headers: {},
+              url: "/500",
+              query: {},
+              cookies: {},
+              remoteAddress: "",
+            },
+            isExternalRewrite: false,
+            isISR: false,
+            origin: false,
+          };
+        }
       }
 
       if ("type" in preprocessResult) {

From e744a790b7f5b839a5a2b5a956bf78d0d40853e5 Mon Sep 17 00:00:00 2001
From: Dorseuil Nicolas <nicodorseuil@yahoo.fr>
Date: Fri, 15 Nov 2024 15:45:05 +0100
Subject: [PATCH 03/12] review fix

---
 packages/open-next/src/adapters/middleware.ts | 5 +++--
 packages/open-next/src/core/requestHandler.ts | 3 +--
 2 files changed, 4 insertions(+), 4 deletions(-)

diff --git a/packages/open-next/src/adapters/middleware.ts b/packages/open-next/src/adapters/middleware.ts
index 634f581c..e65298f0 100644
--- a/packages/open-next/src/adapters/middleware.ts
+++ b/packages/open-next/src/adapters/middleware.ts
@@ -45,9 +45,10 @@ const defaultHandler = async (internalEvent: InternalEvent) => {
       const result = await routingHandler(internalEvent);
       if ("internalEvent" in result) {
         debug("Middleware intercepted event", internalEvent);
-        let origin: Origin | false = false;
         if (!result.isExternalRewrite) {
-          origin = await originResolver.resolve(result.internalEvent.rawPath);
+          const origin = await originResolver.resolve(
+            result.internalEvent.rawPath,
+          );
           return {
             type: "middleware",
             internalEvent: result.internalEvent,
diff --git a/packages/open-next/src/core/requestHandler.ts b/packages/open-next/src/core/requestHandler.ts
index aaacb2bd..08a7d631 100644
--- a/packages/open-next/src/core/requestHandler.ts
+++ b/packages/open-next/src/core/requestHandler.ts
@@ -71,10 +71,9 @@ export async function openNextHandler(
         preprocessResult.isExternalRewrite
       ) {
         try {
-          const proxyResult = await globalThis.proxyExternalRequest.proxy(
+          preprocessResult = await globalThis.proxyExternalRequest.proxy(
             preprocessResult.internalEvent,
           );
-          preprocessResult = proxyResult;
         } catch (e) {
           error("External request failed.", e);
           preprocessResult = {

From 143f1c463d336a232ff598f063271a34de660628 Mon Sep 17 00:00:00 2001
From: Dorseuil Nicolas <nicodorseuil@yahoo.fr>
Date: Fri, 15 Nov 2024 15:50:00 +0100
Subject: [PATCH 04/12] add dummy type everywhere

---
 packages/open-next/src/build/validateConfig.ts |  1 +
 packages/open-next/src/core/resolve.ts         |  3 ++-
 packages/open-next/src/types/open-next.ts      | 17 +++++++++--------
 3 files changed, 12 insertions(+), 9 deletions(-)

diff --git a/packages/open-next/src/build/validateConfig.ts b/packages/open-next/src/build/validateConfig.ts
index e7f84728..451f116b 100644
--- a/packages/open-next/src/build/validateConfig.ts
+++ b/packages/open-next/src/build/validateConfig.ts
@@ -18,6 +18,7 @@ const compatibilityMatrix: Record<IncludedWrapper, IncludedConverter[]> = {
   "aws-lambda-streaming": ["aws-apigw-v2"],
   cloudflare: ["edge"],
   node: ["node"],
+  dummy: [],
 };
 
 function validateFunctionOptions(fnOptions: FunctionOptions) {
diff --git a/packages/open-next/src/core/resolve.ts b/packages/open-next/src/core/resolve.ts
index e6cede42..c63f32fa 100644
--- a/packages/open-next/src/core/resolve.ts
+++ b/packages/open-next/src/core/resolve.ts
@@ -2,6 +2,7 @@ import type {
   BaseEventOrResult,
   DefaultOverrideOptions,
   IncludedProxyExternalRequest,
+  IncludedWarmer,
   InternalEvent,
   InternalResult,
   LazyLoadedOverride,
@@ -124,7 +125,7 @@ export async function resolveOriginResolver(
  * @__PURE__
  */
 export async function resolveWarmerInvoke(
-  warmer?: LazyLoadedOverride<Warmer> | "aws-lambda",
+  warmer?: LazyLoadedOverride<Warmer> | IncludedWarmer,
 ) {
   if (typeof warmer === "function") {
     return warmer();
diff --git a/packages/open-next/src/types/open-next.ts b/packages/open-next/src/types/open-next.ts
index bfa16804..7a1ed705 100644
--- a/packages/open-next/src/types/open-next.ts
+++ b/packages/open-next/src/types/open-next.ts
@@ -80,7 +80,8 @@ export type IncludedWrapper =
   | "aws-lambda"
   | "aws-lambda-streaming"
   | "node"
-  | "cloudflare";
+  | "cloudflare"
+  | "dummy";
 
 export type IncludedConverter =
   | "aws-apigw-v2"
@@ -91,19 +92,19 @@ export type IncludedConverter =
   | "sqs-revalidate"
   | "dummy";
 
-export type IncludedQueue = "sqs" | "sqs-lite";
+export type IncludedQueue = "sqs" | "sqs-lite" | "dummy";
 
-export type IncludedIncrementalCache = "s3" | "s3-lite";
+export type IncludedIncrementalCache = "s3" | "s3-lite" | "dummy";
 
-export type IncludedTagCache = "dynamodb" | "dynamodb-lite";
+export type IncludedTagCache = "dynamodb" | "dynamodb-lite" | "dummy";
 
-export type IncludedImageLoader = "s3" | "host";
+export type IncludedImageLoader = "s3" | "host" | "dummy";
 
-export type IncludedOriginResolver = "pattern-env";
+export type IncludedOriginResolver = "pattern-env" | "dummy";
 
-export type IncludedWarmer = "aws-lambda";
+export type IncludedWarmer = "aws-lambda" | "dummy";
 
-export type IncludedProxyExternalRequest = "node" | "fetch";
+export type IncludedProxyExternalRequest = "node" | "fetch" | "dummy";
 
 export interface DefaultOverrideOptions<
   E extends BaseEventOrResult = InternalEvent,

From ba535b7dda4d587d109e23953d33706c8ddad1ac Mon Sep 17 00:00:00 2001
From: Dorseuil Nicolas <nicodorseuil@yahoo.fr>
Date: Fri, 15 Nov 2024 15:54:24 +0100
Subject: [PATCH 05/12] handle error in middleware

---
 packages/open-next/src/adapters/middleware.ts | 20 +++++++++++++++++--
 1 file changed, 18 insertions(+), 2 deletions(-)

diff --git a/packages/open-next/src/adapters/middleware.ts b/packages/open-next/src/adapters/middleware.ts
index e65298f0..d21eb1c9 100644
--- a/packages/open-next/src/adapters/middleware.ts
+++ b/packages/open-next/src/adapters/middleware.ts
@@ -1,7 +1,7 @@
 import type { InternalEvent, Origin } from "types/open-next";
 import { runWithOpenNextRequestContext } from "utils/promise";
 
-import { debug } from "../adapters/logger";
+import { debug, error } from "../adapters/logger";
 import { createGenericHandler } from "../core/createGenericHandler";
 import {
   resolveIncrementalCache,
@@ -57,7 +57,23 @@ const defaultHandler = async (internalEvent: InternalEvent) => {
             isISR: result.isISR,
           };
         }
-        return externalRequestProxy.proxy(result.internalEvent);
+        try {
+          return externalRequestProxy.proxy(result.internalEvent);
+        } catch (e) {
+          error("External request failed.", e);
+          return {
+            type: "middleware",
+            internalEvent: {
+              ...result.internalEvent,
+              rawPath: "/500",
+              url: "/500",
+              method: "GET",
+            },
+            isExternalRewrite: result.isExternalRewrite,
+            origin: false,
+            isISR: result.isISR,
+          };
+        }
       }
 
       debug("Middleware response", result);

From 2c73d9a6ae09a8e8a2df12a0e94ef9ace49ef0cd Mon Sep 17 00:00:00 2001
From: Dorseuil Nicolas <nicodorseuil@yahoo.fr>
Date: Fri, 15 Nov 2024 16:54:14 +0100
Subject: [PATCH 06/12] review fix

---
 .../src/build/edge/createEdgeBundle.ts        |  4 +++
 packages/open-next/src/core/resolve.ts        | 29 +++++++------------
 packages/open-next/src/types/open-next.ts     |  2 +-
 3 files changed, 16 insertions(+), 19 deletions(-)

diff --git a/packages/open-next/src/build/edge/createEdgeBundle.ts b/packages/open-next/src/build/edge/createEdgeBundle.ts
index d2bbd86a..9ec913c1 100644
--- a/packages/open-next/src/build/edge/createEdgeBundle.ts
+++ b/packages/open-next/src/build/edge/createEdgeBundle.ts
@@ -91,6 +91,10 @@ export async function buildEdgeBundle({
                       : "sqs-lite",
                 }
               : {}),
+            originResolver:
+              typeof overrides?.originResolver === "string"
+                ? overrides.originResolver
+                : "pattern-env",
           },
           fnName: name,
         }),
diff --git a/packages/open-next/src/core/resolve.ts b/packages/open-next/src/core/resolve.ts
index c63f32fa..21970e9e 100644
--- a/packages/open-next/src/core/resolve.ts
+++ b/packages/open-next/src/core/resolve.ts
@@ -1,22 +1,15 @@
 import type {
   BaseEventOrResult,
   DefaultOverrideOptions,
-  IncludedProxyExternalRequest,
-  IncludedWarmer,
   InternalEvent,
   InternalResult,
-  LazyLoadedOverride,
+  OpenNextConfig,
   OverrideOptions,
 } from "types/open-next";
-import type {
-  Converter,
-  ImageLoader,
-  OriginResolver,
-  ProxyExternalRequest,
-  TagCache,
-  Warmer,
-  Wrapper,
-} from "types/overrides";
+import type { Converter, TagCache, Wrapper } from "types/overrides";
+
+// Just a little utility type to remove undefined from a type
+type RemoveUndefined<T> = T extends undefined ? never : T;
 
 export async function resolveConverter<
   E extends BaseEventOrResult = InternalEvent,
@@ -98,7 +91,7 @@ export async function resolveIncrementalCache(
  * @__PURE__
  */
 export async function resolveImageLoader(
-  imageLoader: LazyLoadedOverride<ImageLoader> | string,
+  imageLoader: RemoveUndefined<OpenNextConfig["imageOptimization"]>["loader"],
 ) {
   if (typeof imageLoader === "function") {
     return imageLoader();
@@ -112,7 +105,9 @@ export async function resolveImageLoader(
  * @__PURE__
  */
 export async function resolveOriginResolver(
-  originResolver?: LazyLoadedOverride<OriginResolver> | string,
+  originResolver: RemoveUndefined<
+    OpenNextConfig["middleware"]
+  >["originResolver"],
 ) {
   if (typeof originResolver === "function") {
     return originResolver();
@@ -125,7 +120,7 @@ export async function resolveOriginResolver(
  * @__PURE__
  */
 export async function resolveWarmerInvoke(
-  warmer?: LazyLoadedOverride<Warmer> | IncludedWarmer,
+  warmer: RemoveUndefined<OpenNextConfig["warmer"]>["invokeFunction"],
 ) {
   if (typeof warmer === "function") {
     return warmer();
@@ -138,9 +133,7 @@ export async function resolveWarmerInvoke(
  * @__PURE__
  */
 export async function resolveProxyRequest(
-  proxyRequest?:
-    | LazyLoadedOverride<ProxyExternalRequest>
-    | IncludedProxyExternalRequest,
+  proxyRequest: OverrideOptions["proxyExternalRequest"],
 ) {
   if (typeof proxyRequest === "function") {
     return proxyRequest();
diff --git a/packages/open-next/src/types/open-next.ts b/packages/open-next/src/types/open-next.ts
index 7a1ed705..2138a381 100644
--- a/packages/open-next/src/types/open-next.ts
+++ b/packages/open-next/src/types/open-next.ts
@@ -309,7 +309,7 @@ export interface OpenNextConfig {
    * @default undefined
    */
   warmer?: DefaultFunctionOptions<WarmerEvent, WarmerResponse> & {
-    invokeFunction: IncludedWarmer | LazyLoadedOverride<Warmer>;
+    invokeFunction?: IncludedWarmer | LazyLoadedOverride<Warmer>;
   };
 
   /**

From 3b41f89229837e70063aee139992e8c02f9df810 Mon Sep 17 00:00:00 2001
From: conico974 <nicodorseuil@yahoo.fr>
Date: Mon, 18 Nov 2024 13:05:11 +0100
Subject: [PATCH 07/12] Update packages/open-next/src/core/requestHandler.ts

Co-authored-by: Victor Berchet <victor@suumit.com>
---
 packages/open-next/src/core/requestHandler.ts | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/packages/open-next/src/core/requestHandler.ts b/packages/open-next/src/core/requestHandler.ts
index 08a7d631..519d28dd 100644
--- a/packages/open-next/src/core/requestHandler.ts
+++ b/packages/open-next/src/core/requestHandler.ts
@@ -67,8 +67,7 @@ export async function openNextHandler(
       }
 
       if (
-        "isExternalRewrite" in preprocessResult &&
-        preprocessResult.isExternalRewrite
+        preprocessResult.isExternalRewrite === true
       ) {
         try {
           preprocessResult = await globalThis.proxyExternalRequest.proxy(

From b677414ce2a17123b1b753a039f5e9236051afdc Mon Sep 17 00:00:00 2001
From: Dorseuil Nicolas <nicodorseuil@yahoo.fr>
Date: Mon, 18 Nov 2024 13:11:54 +0100
Subject: [PATCH 08/12] review

---
 packages/open-next/src/core/requestHandler.ts   |  1 +
 .../src/overrides/proxyExternalRequest/node.ts  | 17 ++++++++++-------
 2 files changed, 11 insertions(+), 7 deletions(-)

diff --git a/packages/open-next/src/core/requestHandler.ts b/packages/open-next/src/core/requestHandler.ts
index 519d28dd..aba85dac 100644
--- a/packages/open-next/src/core/requestHandler.ts
+++ b/packages/open-next/src/core/requestHandler.ts
@@ -67,6 +67,7 @@ export async function openNextHandler(
       }
 
       if (
+        "isExternalRewrite" in preprocessResult &&
         preprocessResult.isExternalRewrite === true
       ) {
         try {
diff --git a/packages/open-next/src/overrides/proxyExternalRequest/node.ts b/packages/open-next/src/overrides/proxyExternalRequest/node.ts
index 143b7600..5ab0f465 100644
--- a/packages/open-next/src/overrides/proxyExternalRequest/node.ts
+++ b/packages/open-next/src/overrides/proxyExternalRequest/node.ts
@@ -18,13 +18,16 @@ function filterHeadersForProxy(
     "content-encoding",
     "content-length",
   ];
-  Object.entries(headers).forEach(([key, value]) => {
-    const lowerKey = key.toLowerCase();
-    if (disallowedHeaders.includes(lowerKey) || lowerKey.startsWith("x-amz"))
-      return;
-
-    filteredHeaders[key] = value?.toString() ?? "";
-  });
+  Object.entries(headers)
+    .filter(([key, _]) => {
+      const lowerKey = key.toLowerCase();
+      return !(
+        disallowedHeaders.includes(lowerKey) || lowerKey.startsWith("x-amz")
+      );
+    })
+    .forEach(([key, value]) => {
+      filteredHeaders[key] = value?.toString() ?? "";
+    });
   return filteredHeaders;
 }
 

From d409b7d8f8862b3037921ed54d1c6a686d173177 Mon Sep 17 00:00:00 2001
From: Dorseuil Nicolas <nicodorseuil@yahoo.fr>
Date: Mon, 18 Nov 2024 13:49:14 +0100
Subject: [PATCH 09/12] added comment

---
 packages/open-next/src/adapters/middleware.ts | 3 ++-
 packages/open-next/src/core/requestHandler.ts | 1 +
 2 files changed, 3 insertions(+), 1 deletion(-)

diff --git a/packages/open-next/src/adapters/middleware.ts b/packages/open-next/src/adapters/middleware.ts
index d21eb1c9..952d58fa 100644
--- a/packages/open-next/src/adapters/middleware.ts
+++ b/packages/open-next/src/adapters/middleware.ts
@@ -69,7 +69,8 @@ const defaultHandler = async (internalEvent: InternalEvent) => {
               url: "/500",
               method: "GET",
             },
-            isExternalRewrite: result.isExternalRewrite,
+            // On error we need to rewrite to the 500 page which is an internal rewrite
+            isExternalRewrite: false,
             origin: false,
             isISR: result.isISR,
           };
diff --git a/packages/open-next/src/core/requestHandler.ts b/packages/open-next/src/core/requestHandler.ts
index aba85dac..1030581c 100644
--- a/packages/open-next/src/core/requestHandler.ts
+++ b/packages/open-next/src/core/requestHandler.ts
@@ -87,6 +87,7 @@ export async function openNextHandler(
               cookies: {},
               remoteAddress: "",
             },
+            // On error we need to rewrite to the 500 page which is an internal rewrite
             isExternalRewrite: false,
             isISR: false,
             origin: false,

From fc0f0a4d6f36a877cfd2d795dd9227c1729f319f Mon Sep 17 00:00:00 2001
From: Dorseuil Nicolas <nicodorseuil@yahoo.fr>
Date: Mon, 18 Nov 2024 16:50:57 +0100
Subject: [PATCH 10/12] review fix

---
 .../src/build/edge/createEdgeBundle.ts          |  4 ++++
 packages/open-next/src/plugins/resolve.ts       | 17 ++++-------------
 2 files changed, 8 insertions(+), 13 deletions(-)

diff --git a/packages/open-next/src/build/edge/createEdgeBundle.ts b/packages/open-next/src/build/edge/createEdgeBundle.ts
index 9ec913c1..ce8d785c 100644
--- a/packages/open-next/src/build/edge/createEdgeBundle.ts
+++ b/packages/open-next/src/build/edge/createEdgeBundle.ts
@@ -95,6 +95,10 @@ export async function buildEdgeBundle({
               typeof overrides?.originResolver === "string"
                 ? overrides.originResolver
                 : "pattern-env",
+            proxyExternalRequest:
+              typeof overrides?.proxyExternalRequest === "string"
+                ? overrides.proxyExternalRequest
+                : "node",
           },
           fnName: name,
         }),
diff --git a/packages/open-next/src/plugins/resolve.ts b/packages/open-next/src/plugins/resolve.ts
index 44cf909f..1d138dc9 100644
--- a/packages/open-next/src/plugins/resolve.ts
+++ b/packages/open-next/src/plugins/resolve.ts
@@ -3,27 +3,20 @@ import { readFileSync } from "node:fs";
 import chalk from "chalk";
 import type { Plugin } from "esbuild";
 import type {
-  DefaultOverrideOptions,
   IncludedImageLoader,
   IncludedOriginResolver,
-  IncludedProxyExternalRequest,
   IncludedWarmer,
   LazyLoadedOverride,
   OverrideOptions,
 } from "types/open-next";
-import type {
-  ImageLoader,
-  OriginResolver,
-  ProxyExternalRequest,
-  Warmer,
-} from "types/overrides";
+import type { ImageLoader, OriginResolver, Warmer } from "types/overrides";
 
 import logger from "../logger.js";
 
 export interface IPluginSettings {
   overrides?: {
-    wrapper?: DefaultOverrideOptions<any, any>["wrapper"];
-    converter?: DefaultOverrideOptions<any, any>["converter"];
+    wrapper?: OverrideOptions["wrapper"];
+    converter?: OverrideOptions["converter"];
     tagCache?: OverrideOptions["tagCache"];
     queue?: OverrideOptions["queue"];
     incrementalCache?: OverrideOptions["incrementalCache"];
@@ -32,9 +25,7 @@ export interface IPluginSettings {
       | LazyLoadedOverride<OriginResolver>
       | IncludedOriginResolver;
     warmer?: LazyLoadedOverride<Warmer> | IncludedWarmer;
-    proxyExternalRequest?:
-      | LazyLoadedOverride<ProxyExternalRequest>
-      | IncludedProxyExternalRequest;
+    proxyExternalRequest?: OverrideOptions["proxyExternalRequest"];
   };
   fnName?: string;
 }

From b165231576e3d411517c710444118f4df243090f Mon Sep 17 00:00:00 2001
From: Dorseuil Nicolas <nicodorseuil@yahoo.fr>
Date: Mon, 18 Nov 2024 17:52:22 +0100
Subject: [PATCH 11/12] fix build

---
 packages/open-next/src/plugins/resolve.ts | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/packages/open-next/src/plugins/resolve.ts b/packages/open-next/src/plugins/resolve.ts
index 1d138dc9..aa0b9d35 100644
--- a/packages/open-next/src/plugins/resolve.ts
+++ b/packages/open-next/src/plugins/resolve.ts
@@ -3,6 +3,7 @@ import { readFileSync } from "node:fs";
 import chalk from "chalk";
 import type { Plugin } from "esbuild";
 import type {
+  DefaultOverrideOptions,
   IncludedImageLoader,
   IncludedOriginResolver,
   IncludedWarmer,
@@ -15,8 +16,8 @@ import logger from "../logger.js";
 
 export interface IPluginSettings {
   overrides?: {
-    wrapper?: OverrideOptions["wrapper"];
-    converter?: OverrideOptions["converter"];
+    wrapper?: DefaultOverrideOptions<any, any>["wrapper"];
+    converter?: DefaultOverrideOptions<any, any>["converter"];
     tagCache?: OverrideOptions["tagCache"];
     queue?: OverrideOptions["queue"];
     incrementalCache?: OverrideOptions["incrementalCache"];

From 8ea7d39af8bdb7aa8d62b46231d7e287b36c353b Mon Sep 17 00:00:00 2001
From: conico974 <nicodorseuil@yahoo.fr>
Date: Tue, 19 Nov 2024 14:29:49 +0100
Subject: [PATCH 12/12] Create strong-keys-ring.md

---
 .changeset/strong-keys-ring.md | 5 +++++
 1 file changed, 5 insertions(+)
 create mode 100644 .changeset/strong-keys-ring.md

diff --git a/.changeset/strong-keys-ring.md b/.changeset/strong-keys-ring.md
new file mode 100644
index 00000000..98b70d0c
--- /dev/null
+++ b/.changeset/strong-keys-ring.md
@@ -0,0 +1,5 @@
+---
+"@opennextjs/aws": patch
+---
+
+Feat: Allow overriding the proxying for external rewrite