Use the native node:domain module when available

.changeset/brown-trees-go.md

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

packages/unenv-preset/src/preset.ts

@@ -75,6 +75,7 @@ export function getCloudflarePreset({
 	const punycodeOverrides = getPunycodeOverrides(compat);
 	const clusterOverrides = getClusterOverrides(compat);
 	const traceEventsOverrides = getTraceEventsOverrides(compat);
+	const domainOverrides = getDomainOverrides(compat);
 
 	// "dynamic" as they depend on the compatibility date and flags
 	const dynamicNativeModules = [
@@ -86,6 +87,7 @@ export function getCloudflarePreset({
 		...punycodeOverrides.nativeModules,
 		...clusterOverrides.nativeModules,
 		...traceEventsOverrides.nativeModules,
+		...domainOverrides.nativeModules,
 	];
 
 	// "dynamic" as they depend on the compatibility date and flags
@@ -98,6 +100,7 @@ export function getCloudflarePreset({
 		...punycodeOverrides.hybridModules,
 		...clusterOverrides.hybridModules,
 		...traceEventsOverrides.hybridModules,
+		...domainOverrides.hybridModules,
 	];
 
 	return {
@@ -428,3 +431,41 @@ function getTraceEventsOverrides({
 				hybridModules: [],
 			};
 }
+
+/**
+ * Returns the overrides for `node:domain` (unenv or workerd)
+ *
+ * The native trace_events implementation:
+ * - is experimental
+ * - can be enabled with the "enable_nodejs_domain_module" flag
+ * - can be disabled with the "disable_nodejs_domain_module" flag
+ */
+function getDomainOverrides({
+	// 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_domain_module"
+	);
+
+	// TODO: add `enabledByDate` when a date is defined in workerd
+	const enabledByFlag =
+		compatibilityFlags.includes("enable_nodejs_domain_module") &&
+		compatibilityFlags.includes("experimental");
+
+	const enabled = enabledByFlag && !disabledByFlag;
+
+	return enabled
+		? {
+				nativeModules: ["domain"],
+				hybridModules: [],
+			}
+		: {
+				nativeModules: [],
+				hybridModules: [],
+			};
+}

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

@@ -278,6 +278,7 @@ const localTestConfigs: TestConfig[] = [
 			},
 		},
 	],
+	// trace_events
 	[
 		// TODO: add test for disabled by date (no date defined yet)
 		// TODO: add test for enabled by date (no date defined yet)
@@ -302,6 +303,28 @@ const localTestConfigs: TestConfig[] = [
 			},
 		},
 	],
+	// domain
+	[
+		// TODO: add test for disabled by date (no date defined yet)
+		// TODO: add test for enabled by date (no date defined yet)
+		{
+			name: "domain enabled by flag",
+			compatibilityDate: "2024-09-23",
+			compatibilityFlags: ["enable_nodejs_domain_module", "experimental"],
+			expectRuntimeFlags: {
+				enable_nodejs_domain_module: true,
+			},
+		},
+		// TODO: update the date past the default enable date (when defined)
+		{
+			name: "domain disabled by flag",
+			compatibilityDate: "2024-09-23",
+			compatibilityFlags: ["disable_nodejs_domain_module", "experimental"],
+			expectRuntimeFlags: {
+				enable_nodejs_domain_module: false,
+			},
+		},
+	],
 ].flat() as TestConfig[];
 
 describe.each(localTestConfigs)(

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

@@ -596,6 +596,17 @@ export const WorkerdTests: Record<string, () => void> = {
 		assertTypeOf(tracing, "enabled", "boolean");
 		assertTypeOf(tracing, "categories", "string");
 	},
+
+	async testDomain() {
+		const { Domain } = await import("node:domain");
+
+		const domain = new Domain();
+
+		assertTypeOf(domain, "add", "function");
+		assertTypeOf(domain, "enter", "function");
+		assertTypeOf(domain, "exit", "function");
+		assertTypeOf(domain, "remove", "function");
+	},
 };
 
 function assertTypeOf(target: unknown, property: string, expectType: string) {