Use the native node:wasi module when available (#11025)

Co-authored-by: Devin AI <158243242+devin-ai-integration[bot]@users.noreply.github.com>
Co-authored-by: [email protected] <[email protected]>

Author: devin-ai-integration[bot]

.changeset/yummy-geckos-bet.md

@@ -0,0 +1,8 @@
+---
+"@cloudflare/unenv-preset": patch
+"wrangler": patch
+---
+
+Use the native `node:wasi` module when available
+
+It is enabled when the `enable_nodejs_wasi_module` compatibility flag is set.

packages/unenv-preset/src/preset.ts

@@ -76,6 +76,7 @@ export function getCloudflarePreset({
 	const clusterOverrides = getClusterOverrides(compat);
 	const traceEventsOverrides = getTraceEventsOverrides(compat);
 	const domainOverrides = getDomainOverrides(compat);
+	const wasiOverrides = getWasiOverrides(compat);
 
 	// "dynamic" as they depend on the compatibility date and flags
 	const dynamicNativeModules = [
@@ -88,6 +89,7 @@ export function getCloudflarePreset({
 		...clusterOverrides.nativeModules,
 		...traceEventsOverrides.nativeModules,
 		...domainOverrides.nativeModules,
+		...wasiOverrides.nativeModules,
 	];
 
 	// "dynamic" as they depend on the compatibility date and flags
@@ -101,6 +103,7 @@ export function getCloudflarePreset({
 		...clusterOverrides.hybridModules,
 		...traceEventsOverrides.hybridModules,
 		...domainOverrides.hybridModules,
+		...wasiOverrides.hybridModules,
 	];
 
 	return {
@@ -469,3 +472,41 @@ function getDomainOverrides({
 				hybridModules: [],
 			};
 }
+
+/**
+ * Returns the overrides for `node:wasi` (unenv or workerd)
+ *
+ * The native wasi implementation:
+ * - is experimental
+ * - can be enabled with the "enable_nodejs_wasi_module" flag
+ * - can be disabled with the "disable_nodejs_wasi_module" flag
+ */
+function getWasiOverrides({
+	// eslint-disable-next-line unused-imports/no-unused-vars
+	compatibilityDate,
+	compatibilityFlags,
+}: {
+	compatibilityDate: string;
+	compatibilityFlags: string[];
+}): { nativeModules: string[]; hybridModules: string[] } {
+	const disabledByFlag = compatibilityFlags.includes(
+		"disable_nodejs_wasi_module"
+	);
+
+	// TODO: add `enabledByDate` when a date is defined in workerd
+	const enabledByFlag =
+		compatibilityFlags.includes("enable_nodejs_wasi_module") &&
+		compatibilityFlags.includes("experimental");
+
+	const enabled = enabledByFlag && !disabledByFlag;
+
+	return enabled
+		? {
+				nativeModules: ["wasi"],
+				hybridModules: [],
+			}
+		: {
+				nativeModules: [],
+				hybridModules: [],
+			};
+}

packages/wrangler/e2e/unenv-preset/preset.test.ts

@@ -325,6 +325,28 @@ const localTestConfigs: TestConfig[] = [
 			},
 		},
 	],
+	// wasi
+	[
+		// TODO: add test for disabled by date (no date defined yet)
+		// TODO: add test for enabled by date (no date defined yet)
+		{
+			name: "wasi enabled by flag",
+			compatibilityDate: "2024-09-23",
+			compatibilityFlags: ["enable_nodejs_wasi_module", "experimental"],
+			expectRuntimeFlags: {
+				enable_nodejs_wasi_module: true,
+			},
+		},
+		// TODO: update the date past the default enable date (when defined)
+		{
+			name: "wasi disabled by flag",
+			compatibilityDate: "2024-09-23",
+			compatibilityFlags: ["disable_nodejs_wasi_module", "experimental"],
+			expectRuntimeFlags: {
+				enable_nodejs_wasi_module: false,
+			},
+		},
+	],
 ].flat() as TestConfig[];
 
 describe.each(localTestConfigs)(

packages/wrangler/e2e/unenv-preset/worker/index.ts

@@ -607,6 +607,18 @@ export const WorkerdTests: Record<string, () => void> = {
 		assertTypeOf(domain, "exit", "function");
 		assertTypeOf(domain, "remove", "function");
 	},
+
+	async testWasi() {
+		const wasi = await import("node:wasi");
+
+		assert.strictEqual(typeof wasi.WASI, "function");
+
+		assert.throws(() => new wasi.WASI(), /not implemented/);
+		assert.throws(
+			() => new wasi.WASI({ version: "preview1" }),
+			/not implemented/
+		);
+	},
 };
 
 function assertTypeOf(target: unknown, property: string, expectType: string) {