Improve custom config support (#416)

* fix missing fnName in the function

* compile open-next to node by default

* compile config for edge

.changeset/orange-bees-lie.md

@@ -0,0 +1,5 @@
+---
+"open-next": patch
+---
+
+Improve custom config support

packages/open-next/src/build.ts

@@ -5,10 +5,13 @@ import os from "node:os";
 import path from "node:path";
 import url from "node:url";
 
-import { buildSync } from "esbuild";
 import { MiddlewareManifest } from "types/next-types.js";
 
 import { isBinaryContentType } from "./adapters/binary.js";
+import {
+  compileOpenNextConfigEdge,
+  compileOpenNextConfigNode,
+} from "./build/compileConfig.js";
 import { createServerBundle } from "./build/createServerBundle.js";
 import { buildEdgeBundle } from "./build/edge/createEdgeBundle.js";
 import { generateOutput } from "./build/generateOutput.js";
@@ -39,15 +42,24 @@ export type PublicFiles = {
   files: string[];
 };
 
-export async function build(openNextConfigPath?: string) {
+export async function build(
+  openNextConfigPath?: string,
+  nodeExternals?: string,
+) {
   showWindowsWarning();
 
   // Load open-next.config.ts
   const tempDir = initTempDir();
-  const configPath = compileOpenNextConfig(tempDir, openNextConfigPath);
+  const configPath = compileOpenNextConfigNode(
+    tempDir,
+    openNextConfigPath,
+    nodeExternals,
+  );
   config = (await import(configPath)).default as OpenNextConfig;
   validateConfig(config);
 
+  compileOpenNextConfigEdge(tempDir, config, openNextConfigPath);
+
   const { root: monorepoRoot, packager } = findMonorepoRoot(
     path.join(process.cwd(), config.appPath || "."),
   );
@@ -107,40 +119,6 @@ function initTempDir() {
   return tempDir;
 }
 
-function compileOpenNextConfig(tempDir: string, openNextConfigPath?: string) {
-  const sourcePath = path.join(
-    process.cwd(),
-    openNextConfigPath ?? "open-next.config.ts",
-  );
-  const outputPath = path.join(tempDir, "open-next.config.mjs");
-
-  //Check if open-next.config.ts exists
-  if (!fs.existsSync(sourcePath)) {
-    //Create a simple open-next.config.mjs file
-    logger.debug("Cannot find open-next.config.ts. Using default config.");
-    fs.writeFileSync(
-      outputPath,
-      [
-        "var config = { default: { } };",
-        "var open_next_config_default = config;",
-        "export { open_next_config_default as default };",
-      ].join("\n"),
-    );
-  } else {
-    buildSync({
-      entryPoints: [sourcePath],
-      outfile: outputPath,
-      bundle: true,
-      format: "esm",
-      target: ["node18"],
-      external: ["node:*"],
-      platform: "neutral",
-    });
-  }
-
-  return outputPath;
-}
-
 function checkRunningInsideNextjsApp() {
   const { appPath } = options;
   const extension = ["js", "cjs", "mjs"].find((ext) =>
@@ -228,9 +206,22 @@ function initOutputDir() {
     path.join(tempDir, "open-next.config.mjs"),
     "utf8",
   );
+  let openNextConfigEdge: string | null = null;
+  if (fs.existsSync(path.join(tempDir, "open-next.config.edge.mjs"))) {
+    openNextConfigEdge = readFileSync(
+      path.join(tempDir, "open-next.config.edge.mjs"),
+      "utf8",
+    );
+  }
   fs.rmSync(outputDir, { recursive: true, force: true });
   fs.mkdirSync(tempDir, { recursive: true });
   fs.writeFileSync(path.join(tempDir, "open-next.config.mjs"), openNextConfig);
+  if (openNextConfigEdge) {
+    fs.writeFileSync(
+      path.join(tempDir, "open-next.config.edge.mjs"),
+      openNextConfigEdge,
+    );
+  }
 }
 
 async function createWarmerBundle(config: OpenNextConfig) {

packages/open-next/src/build/compileConfig.ts

@@ -0,0 +1,90 @@
+import fs from "node:fs";
+import path from "node:path";
+
+import { buildSync } from "esbuild";
+import { OpenNextConfig } from "types/open-next.js";
+
+import logger from "../logger.js";
+
+export function compileOpenNextConfigNode(
+  tempDir: string,
+  openNextConfigPath?: string,
+  nodeExternals?: string,
+) {
+  const sourcePath = path.join(
+    process.cwd(),
+    openNextConfigPath ?? "open-next.config.ts",
+  );
+  const outputPath = path.join(tempDir, "open-next.config.mjs");
+
+  //Check if open-next.config.ts exists
+  if (!fs.existsSync(sourcePath)) {
+    //Create a simple open-next.config.mjs file
+    logger.debug("Cannot find open-next.config.ts. Using default config.");
+    fs.writeFileSync(
+      outputPath,
+      [
+        "var config = { default: { } };",
+        "var open_next_config_default = config;",
+        "export { open_next_config_default as default };",
+      ].join("\n"),
+    );
+  } else {
+    buildSync({
+      entryPoints: [sourcePath],
+      outfile: outputPath,
+      bundle: true,
+      format: "esm",
+      target: ["node18"],
+      external: nodeExternals ? nodeExternals.split(",") : [],
+      platform: "node",
+      banner: {
+        js: [
+          "import { createRequire as topLevelCreateRequire } from 'module';",
+          "const require = topLevelCreateRequire(import.meta.url);",
+          "import bannerUrl from 'url';",
+          "const __dirname = bannerUrl.fileURLToPath(new URL('.', import.meta.url));",
+        ].join(""),
+      },
+    });
+  }
+
+  return outputPath;
+}
+
+export function compileOpenNextConfigEdge(
+  tempDir: string,
+  config: OpenNextConfig,
+  openNextConfigPath?: string,
+) {
+  const sourcePath = path.join(
+    process.cwd(),
+    openNextConfigPath ?? "open-next.config.ts",
+  );
+  const outputPath = path.join(tempDir, "open-next.config.edge.mjs");
+
+  // We need to check if the config uses the edge runtime at any point
+  // If it does, we need to compile it with the edge runtime
+  const usesEdgeRuntime =
+    config.middleware?.external ||
+    Object.values(config.functions || {}).some((fn) => fn.runtime === "edge");
+  if (!usesEdgeRuntime) {
+    logger.debug(
+      "No edge runtime found in the open-next.config.ts. Using default config.",
+    );
+    //Nothing to do here
+  } else {
+    logger.info("Compiling open-next.config.ts for edge runtime.", outputPath);
+    buildSync({
+      entryPoints: [sourcePath],
+      outfile: outputPath,
+      bundle: true,
+      format: "esm",
+      target: ["es2020"],
+      conditions: ["worker", "browser"],
+      platform: "browser",
+      external: config.edgeExternals ?? [],
+    });
+    logger.info("Compiled open-next.config.ts for edge runtime.");
+  }
+}

packages/open-next/src/build/createServerBundle.ts

@@ -257,6 +257,7 @@ async function generateBundle(
           "const require = topLevelCreateRequire(import.meta.url);",
           "import bannerUrl from 'url';",
           "const __dirname = bannerUrl.fileURLToPath(new URL('.', import.meta.url));",
+          name === "default" ? "" : `globalThis.fnName = "${name}";`,
         ].join(""),
       },
       plugins,

packages/open-next/src/build/edge/createEdgeBundle.ts

@@ -114,7 +114,7 @@ export async function generateEdgeBundle(
   fs.mkdirSync(outputPath, { recursive: true });
 
   // Copy open-next.config.mjs
-  copyOpenNextConfig(path.join(outputDir, ".build"), outputPath);
+  copyOpenNextConfig(path.join(outputDir, ".build"), outputPath, true);
 
   // Load middleware manifest
   const middlewareManifest = JSON.parse(

packages/open-next/src/build/helper.ts

@@ -240,10 +240,17 @@ export function compareSemver(v1: string, v2: string): number {
   return patch1 - patch2;
 }
 
-export function copyOpenNextConfig(tempDir: string, outputPath: string) {
+export function copyOpenNextConfig(
+  tempDir: string,
+  outputPath: string,
+  isEdge = false,
+) {
   // Copy open-next.config.mjs
   fs.copyFileSync(
-    path.join(tempDir, "open-next.config.mjs"),
+    path.join(
+      tempDir,
+      isEdge ? "open-next.config.edge.mjs" : "open-next.config.mjs",
+    ),
     path.join(outputPath, "open-next.config.mjs"),
   );
 }

packages/open-next/src/index.ts

@@ -8,7 +8,7 @@ if (command !== "build") printHelp();
 const args = parseArgs();
 if (Object.keys(args).includes("--help")) printHelp();
 
-build(args["--config-path"]);
+build(args["--config-path"], args["--node-externals"]);
 
 function parseArgs() {
   return process.argv.slice(2).reduce(
@@ -33,9 +33,14 @@ function printHelp() {
   console.log("");
   console.log("Usage:");
   console.log("  npx open-next build");
+  console.log("You can use a custom config path here");
   console.log(
     "  npx open-next build --config-path ./path/to/open-next.config.ts",
   );
+  console.log(
+    "You can configure externals for the esbuild compilation of the open-next.config.ts file",
+  );
+  console.log("  npx open-next build --node-externals aws-sdk,sharp,sqlite3");
   console.log("");
 
   process.exit(1);

packages/open-next/src/types/open-next.ts

@@ -306,6 +306,10 @@ export interface OpenNextConfig {
     tagCache?: "dynamodb" | LazyLoadedOverride<TagCache>;
   };
 
+  /**
+   * Dangerous options. This break some functionnality but can be useful in some cases.
+   */
+  dangerous?: DangerousOptions;
   /**
    * The command to build the Next.js app.
    * @default `npm run build`, `yarn build`, or `pnpm build` based on the lock file found in the app's directory or any of its parent directories.
@@ -316,10 +320,6 @@ export interface OpenNextConfig {
    * });
    * ```
    */
-  /**
-   * Dangerous options. This break some functionnality but can be useful in some cases.
-   */
-  dangerous?: DangerousOptions;
   buildCommand?: string;
   /**
    * The path to the target folder of build output from the `buildCommand` option (the path which will contain the `.next` and `.open-next` folders). This path is relative from the current process.cwd().
@@ -336,4 +336,13 @@ export interface OpenNextConfig {
    * @default "."
    */
   packageJsonPath?: string;
+  /**
+   * **Advanced usage**
+   * If you use the edge runtime somewhere (either in the middleware or in the functions), we compile 2 versions of the open-next.config.ts file.
+   * One for the node runtime and one for the edge runtime.
+   * This option allows you to specify the externals for the edge runtime used in esbuild for the compilation of open-next.config.ts
+   * It is especially useful if you use some custom overrides only in node
+   * @default []
+   */
+  edgeExternals?: string[];
 }