feat: add support for custom unenv resolve path

.changeset/fluffy-eggs-film.md

@@ -0,0 +1,11 @@
+---
+"wrangler": minor
+---
+
+feat(wrangler): allow overriding the unenv preset.
+
+By default wrangler uses the bundled unenv preset.
+
+Setting `WRANGLER_UNENV_RESOLVE_PATHS` allow to use another version of the preset.
+Those paths are used when resolving the unenv module identifiers to absolute paths.
+This can be used to test a development version.

packages/wrangler/src/deployment-bundle/bundle.ts

@@ -5,6 +5,7 @@ import * as esbuild from "esbuild";
 import {
 	getBuildConditionsFromEnv,
 	getBuildPlatformFromEnv,
+	getUnenvResolvePathsFromEnv,
 } from "../environment-variables/misc-variables";
 import { UserError } from "../errors";
 import { getFlag } from "../experimental-flags";
@@ -390,6 +391,8 @@ export async function bundleWorker(
 		},
 	};
 
+	const unenvResolvePaths = getUnenvResolvePathsFromEnv()?.split(",");
+
 	const buildOptions: esbuild.BuildOptions & { metafile: true } = {
 		// Don't use entryFile here as the file may have been changed when applying the middleware
 		entryPoints: [entry.file],
@@ -435,7 +438,10 @@ export async function bundleWorker(
 		plugins: [
 			aliasPlugin,
 			moduleCollector.plugin,
-			...getNodeJSCompatPlugins(nodejsCompatMode ?? null),
+			...getNodeJSCompatPlugins({
+				mode: nodejsCompatMode ?? null,
+				unenvResolvePaths,
+			}),
 			cloudflareInternalPlugin,
 			buildResultPlugin,
 			...(plugins || []),

packages/wrangler/src/deployment-bundle/esbuild-plugins/hybrid-nodejs-compat.ts

@@ -8,12 +8,20 @@ import type { Plugin, PluginBuild } from "esbuild";
 const REQUIRED_NODE_BUILT_IN_NAMESPACE = "node-built-in-modules";
 const REQUIRED_UNENV_ALIAS_NAMESPACE = "required-unenv-alias";
 
-export const nodejsHybridPlugin: () => Plugin = () => {
+/**
+ * ESBuild plugin to apply the unenv preset.
+ *
+ * @param unenvResolvePaths Root paths used to resolve absolute paths.
+ * @returns ESBuild plugin
+ */
+export function nodejsHybridPlugin(unenvResolvePaths?: string[]): Plugin {
 	// Get the resolved environment.
 	const { env } = defineEnv({
 		nodeCompat: true,
 		presets: [cloudflare],
-		resolve: true,
+		resolve: {
+			paths: unenvResolvePaths,
+		},
 	});
 	const { alias, inject, external } = env;
 	// Get the unresolved alias.
@@ -31,7 +39,7 @@ export const nodejsHybridPlugin: () => Plugin = () => {
 			handleNodeJSGlobals(build, inject);
 		},
 	};
-};
+}
 
 const NODEJS_MODULES_RE = new RegExp(`^(node:)?(${builtinModules.join("|")})$`);
 

packages/wrangler/src/deployment-bundle/esbuild-plugins/nodejs-plugins.ts

@@ -10,7 +10,13 @@ import type { NodeJSCompatMode } from "miniflare";
 /**
  * Returns the list of ESBuild plugins to use for a given compat mode.
  */
-export function getNodeJSCompatPlugins(mode: NodeJSCompatMode): Plugin[] {
+export function getNodeJSCompatPlugins({
+	mode,
+	unenvResolvePaths,
+}: {
+	mode: NodeJSCompatMode;
+	unenvResolvePaths?: string[];
+}): Plugin[] {
 	switch (mode) {
 		case "als":
 			return [asyncLocalStoragePlugin, nodejsCompatPlugin(mode)];
@@ -24,7 +30,7 @@ export function getNodeJSCompatPlugins(mode: NodeJSCompatMode): Plugin[] {
 		case "v1":
 			return [nodejsCompatPlugin(mode)];
 		case "v2":
-			return [nodejsHybridPlugin()];
+			return [nodejsHybridPlugin(unenvResolvePaths)];
 		case null:
 			return [nodejsCompatPlugin(mode)];
 	}

packages/wrangler/src/environment-variables/factory.ts

@@ -25,6 +25,7 @@ type VariableNames =
 	| "WRANGLER_CI_MATCH_TAG"
 	| "WRANGLER_BUILD_CONDITIONS"
 	| "WRANGLER_BUILD_PLATFORM"
+	| "WRANGLER_UNENV_RESOLVE_PATHS"
 	| "WRANGLER_REGISTRY_PATH";
 
 type DeprecatedNames =

packages/wrangler/src/environment-variables/misc-variables.ts

@@ -126,6 +126,19 @@ export const getBuildPlatformFromEnv = getEnvironmentVariableFactory({
 	variableName: "WRANGLER_BUILD_PLATFORM",
 });
 
+/**
+ * `WRANGLER_UNENV_RESOLVE_PATHS` lists the paths used to resolve unenv.
+ *
+ * Note: multiple comma separated paths can be specified.
+ *
+ * By default wrangler uses the unenv preset version installed from the package.json.
+ *
+ * Setting root paths allow to use a different version of the preset.
+ */
+export const getUnenvResolvePathsFromEnv = getEnvironmentVariableFactory({
+	variableName: "WRANGLER_UNENV_RESOLVE_PATHS",
+});
+
 /**
  * `WRANGLER_REGISTRY_PATH` specifies the file based dev registry folder
  */