fix(telemetry): make DO_NOT_TRACK actually disable metrics

ariesclark · ariesclark · commit 8ce42a30a72c · 2026-07-29T18:30:56.000-04:00
diff --git a/.changeset/nine-taxis-shave.md b/.changeset/nine-taxis-shave.md
@@ -0,0 +1,9 @@
+---
+"create-cloudflare": patch
+"@cloudflare/workers-utils": patch
+"wrangler": patch
+---
+
+Support the `DO_NOT_TRACK` environment variable as a telemetry opt-out
+
+Setting `DO_NOT_TRACK=1` (see https://donottrack.sh/) disables telemetry in both Wrangler and `create-cloudflare`. The tool-specific variables `WRANGLER_SEND_METRICS` and `CREATE_CLOUDFLARE_TELEMETRY_DISABLED` still take precedence.
diff --git a/packages/create-cloudflare/src/__tests__/metrics.test.ts b/packages/create-cloudflare/src/__tests__/metrics.test.ts
@@ -259,6 +259,33 @@ describe("createReporter", () => {
 		expect(sendEvent).toHaveBeenCalledTimes(0);
 	});
 
+	test("sends no event if the DO_NOT_TRACK env is set to '1'", async ({
+		expect,
+	}) => {
+		vi.stubEnv("DO_NOT_TRACK", "1");
+
+		const deferred = promiseWithResolvers<string>();
+		const reporter = createReporter();
+		const operation = reporter.collectAsyncMetrics({
+			eventPrefix: "c3 session",
+			props: {
+				args: {
+					projectName: "app",
+				},
+			},
+			promise: () => deferred.promise,
+		});
+
+		expect(reporter.isEnabled).toBe(false);
+
+		expect(sendEvent).toHaveBeenCalledTimes(0);
+
+		deferred.resolve("test result");
+
+		await expect(operation).resolves.toBe("test result");
+		expect(sendEvent).toHaveBeenCalledTimes(0);
+	});
+
 	test("sends started and cancelled event to sparrow if the promise reject with a CancelError", async ({
 		expect,
 	}) => {
diff --git a/packages/create-cloudflare/src/metrics.ts b/packages/create-cloudflare/src/metrics.ts
@@ -2,6 +2,7 @@ import { AsyncLocalStorage } from "node:async_hooks";
 import { setTimeout } from "node:timers/promises";
 import { logRaw } from "@cloudflare/cli-shared-helpers";
 import { CancelError } from "@cloudflare/cli-shared-helpers/error";
+import { isDoNotTrackEnabled } from "@cloudflare/workers-utils";
 import {
 	getDeviceId,
 	readMetricsConfig,
@@ -110,7 +111,10 @@ export function createReporter() {
 	}
 
 	function isTelemetryEnabled() {
-		if (process.env.CREATE_CLOUDFLARE_TELEMETRY_DISABLED === "1" || process.env.DO_NOT_TRACK === "1") {
+		if (
+			process.env.CREATE_CLOUDFLARE_TELEMETRY_DISABLED === "1" ||
+			isDoNotTrackEnabled()
+		) {
 			return false;
 		}
 
diff --git a/packages/workers-utils/src/environment-variables/misc-variables.ts b/packages/workers-utils/src/environment-variables/misc-variables.ts
@@ -37,17 +37,35 @@ export const getC3CommandFromEnv = getEnvironmentVariableFactory({
 	defaultValue: () => "create cloudflare",
 });
 
+const getDoNotTrackFromEnv = getEnvironmentVariableFactory({
+	variableName: "DO_NOT_TRACK",
+});
+
 /**
- * `WRANGLER_SEND_METRICS` and `DO_NOT_TRACK` can override whether we attempt to send
- * metrics information to Sparrow.
+ * `DO_NOT_TRACK` is a shared telemetry opt-out convention: https://donottrack.sh/
  */
-export const getWranglerSendMetricsFromEnv =
+export function isDoNotTrackEnabled(): boolean {
+	const value = getDoNotTrackFromEnv()?.toLowerCase();
+	return value === "1" || value === "true";
+}
+
+const getWranglerSendMetricsVariableFromEnv =
 	getBooleanEnvironmentVariableFactory({
 		variableName: "WRANGLER_SEND_METRICS",
-	}) || getBooleanEnvironmentVariableFactory({
-		variableName: "DO_NOT_TRACK",
 	});
 
+/**
+ * `WRANGLER_SEND_METRICS` can override whether we attempt to send metrics information to Sparrow.
+ *
+ * When it is unset, `DO_NOT_TRACK` opts out of sending metrics.
+ */
+export function getWranglerSendMetricsFromEnv(): boolean | undefined {
+	return (
+		getWranglerSendMetricsVariableFromEnv() ??
+		(isDoNotTrackEnabled() ? false : undefined)
+	);
+}
+
 /**
  * `WRANGLER_SEND_ERROR_REPORTS` controls whether we attempt to send error reports to Sentry.
  *
diff --git a/packages/wrangler/src/__tests__/metrics.test.ts b/packages/wrangler/src/__tests__/metrics.test.ts
@@ -679,6 +679,34 @@ describe("metrics", () => {
 				});
 			});
 
+			it("should return enabled false if the DO_NOT_TRACK environment variable is set", async ({
+				expect,
+			}) => {
+				vi.stubEnv("DO_NOT_TRACK", "1");
+				expect(await getMetricsConfig({ sendMetrics: true })).toMatchObject({
+					enabled: false,
+				});
+			});
+
+			it("should let the WRANGLER_SEND_METRICS environment variable override DO_NOT_TRACK", async ({
+				expect,
+			}) => {
+				vi.stubEnv("DO_NOT_TRACK", "1");
+				vi.stubEnv("WRANGLER_SEND_METRICS", "true");
+				expect(await getMetricsConfig({})).toMatchObject({
+					enabled: true,
+				});
+			});
+
+			it("should ignore DO_NOT_TRACK if it is not set to an opt-out value", async ({
+				expect,
+			}) => {
+				vi.stubEnv("DO_NOT_TRACK", "0");
+				expect(await getMetricsConfig({ sendMetrics: true })).toMatchObject({
+					enabled: true,
+				});
+			});
+
 			it("should return the sendMetrics argument for enabled if it is defined", async ({
 				expect,
 			}) => {
diff --git a/packages/wrangler/telemetry.md b/packages/wrangler/telemetry.md
@@ -81,6 +81,8 @@ Wrangler also honors [`DO_NOT_TRACK`](https://donottrack.sh/), a shared opt-out
 export DO_NOT_TRACK=1
 ```
 
+Setting `WRANGLER_SEND_METRICS` takes precedence, so `WRANGLER_SEND_METRICS=true` re-enables Wrangler telemetry even when `DO_NOT_TRACK` is set.
+
 If you would like to re-enable telemetry globally, you can run:
 
 ```sh
