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Merged
brkalow merged 2 commits into from
Jul 14, 2026
Merged

fix(nextjs): add auto proxy opt-out #9159

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c6bf6d3
fix(repo): add Vercel auto-proxy opt-out
brkalow Jul 14, 2026
cf141a6
Merge branch 'main' into brk/disable-vercel-auto-proxy
brkalow Jul 14, 2026
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7 changes: 7 additions & 0 deletions .changeset/disable-vercel-auto-proxy.md
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Original file line number Diff line number Diff line change
@@ -0,0 +1,7 @@
---
'@clerk/backend': patch
'@clerk/nextjs': patch
'@clerk/shared': patch
---

Add `CLERK_DISABLE_AUTO_PROXY=true` to opt out of automatic Frontend API proxying on Vercel production deployments.
10 changes: 10 additions & 0 deletions packages/backend/src/tokens/__tests__/authenticateContext.test.ts
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Expand Up @@ -302,6 +302,16 @@ describe('AuthenticateContext', () => {
expect(context.proxyUrl).toBeUndefined();
});

it('does NOT auto-derive proxyUrl when auto-proxy is disabled', async () => {
process.env.CLERK_DISABLE_AUTO_PROXY = 'true';
const clerkRequest = createClerkRequest(new Request('https://myapp-abc123.vercel.app/dashboard'));
const context = await createAuthenticateContext(clerkRequest, {
publishableKey: pkLive,
});

expect(context.proxyUrl).toBeUndefined();
});

it('explicit proxyUrl takes precedence over auto-detection', async () => {
const clerkRequest = createClerkRequest(new Request('https://myapp-abc123.vercel.app/dashboard'));
const context = await createAuthenticateContext(clerkRequest, {
Expand Down
9 changes: 7 additions & 2 deletions packages/nextjs/src/server/clerkMiddleware.ts
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Expand Up @@ -25,7 +25,7 @@ import { clerkFrontendApiProxy, DEFAULT_PROXY_PATH, matchProxyPath } from '@cler
import { isProductionFromPublishableKey, parsePublishableKey } from '@clerk/shared/keys';
import { handleNetlifyCacheInDevInstance } from '@clerk/shared/netlifyCacheHandler';
import { isMalformedURLError } from '@clerk/shared/pathMatcher';
import { shouldAutoProxy } from '@clerk/shared/proxy';
import { isAutoProxyDisabledFromEnvironment, shouldAutoProxy } from '@clerk/shared/proxy';
import { notFound as nextjsNotFound } from 'next/navigation';
import type { NextMiddleware, NextRequest } from 'next/server';
import { NextResponse } from 'next/server';
Expand Down Expand Up @@ -168,7 +168,12 @@ export const clerkMiddleware = ((...args: unknown[]): NextMiddleware | NextMiddl

// Auto-detect when no explicit proxy or domain is configured
const hasExplicitProxyOrDomain = resolvedParams.proxyUrl || PROXY_URL || resolvedParams.domain || DOMAIN;
if (!frontendApiProxyConfig && !hasExplicitProxyOrDomain && isProductionFromPublishableKey(publishableKey)) {
if (
!frontendApiProxyConfig &&
!hasExplicitProxyOrDomain &&
!isAutoProxyDisabledFromEnvironment() &&
isProductionFromPublishableKey(publishableKey)
) {
Comment on lines +171 to +176

@coderabbitai coderabbitai Bot Jul 14, 2026

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📐 Maintainability & Code Quality | 🟡 Minor | ⚡ Quick win

🧩 Analysis chain

🏁 Script executed:

#!/bin/bash
set -euo pipefail

echo "== clerkMiddleware excerpt =="
sed -n '130,220p' packages/nextjs/src/server/clerkMiddleware.ts

echo
echo "== search for auto proxy / disable auto proxy / middleware tests =="
rg -n "CLERK_DISABLE_AUTO_PROXY|isAutoProxyDisabledFromEnvironment|proxy handler|auto proxy|frontendApiProxyConfig|hasExplicitProxyOrDomain|isProductionFromPublishableKey|vercel" packages/nextjs -g '*.{ts,tsx,test.ts,test.tsx,spec.ts,spec.tsx}'

echo
echo "== list test files near nextjs server middleware =="
fd -a "clerkMiddleware" packages/nextjs
fd -a "middleware" packages/nextjs/src packages/nextjs/test packages/nextjs/__tests__ 2>/dev/null || true

Repository: clerk/javascript

Length of output: 9457

🏁 Script executed:

#!/bin/bash
set -euo pipefail

echo "== repo files of interest =="
git ls-files 'packages/nextjs/**/*' | rg 'clerkMiddleware|middleware|proxy|vercel|test|spec'

echo
echo "== text search for disable auto proxy across repo =="
rg -n "CLERK_DISABLE_AUTO_PROXY|isAutoProxyDisabledFromEnvironment|auto proxy|proxy handler|frontendApiProxyConfig|hasExplicitProxyOrDomain|isProductionFromPublishableKey" .

echo
echo "== if tests exist, print filenames =="
rg -l "CLERK_DISABLE_AUTO_PROXY|isAutoProxyDisabledFromEnvironment|isProductionFromPublishableKey" packages/nextjs

Repository: clerk/javascript

Length of output: 4975

🏁 Script executed:

#!/bin/bash
set -euo pipefail

echo "== candidate test files =="
fd -a -e ts -e tsx -e test.ts -e spec.ts packages/nextjs | rg 'clerkMiddleware|middleware|proxy|vercel'

echo
echo "== read smallest likely test files =="
for f in $(fd -a -e ts -e tsx -e test.ts -e spec.ts packages/nextjs | rg 'clerkMiddleware|middleware|proxy|vercel' | head -n 10); do
  echo "---- $f ----"
  wc -l "$f"
  sed -n '1,260p' "$f"
done

Repository: clerk/javascript

Length of output: 547

🏁 Script executed:

#!/bin/bash
set -euo pipefail

TEST=packages/nextjs/src/server/__tests__/clerkMiddleware.test.ts

echo "== file size =="
wc -l "$TEST"

echo
echo "== outline =="
ast-grep outline "$TEST" --view expanded | sed -n '1,260p'

echo
echo "== relevant ranges around vercel/proxy tests =="
sed -n '1160,1395p' "$TEST"

echo
echo "== search for CLERK_DISABLE_AUTO_PROXY in clerkMiddleware.test.ts =="
rg -n "CLERK_DISABLE_AUTO_PROXY|shouldAutoProxy|proxy handler|frontendApiProxy|vercel" "$TEST"

Repository: clerk/javascript

Length of output: 11562

Add coverage for the auto-proxy opt-out branch. clerkMiddleware makes this decision independently, so add a middleware test with CLERK_DISABLE_AUTO_PROXY=true, a live key, and an eligible Vercel hostname, and assert the proxy handler is skipped.

🤖 Prompt for AI Agents 
Verify each finding against current code. Fix only still-valid issues, skip the
rest with a brief reason, keep changes minimal, and validate.

In `@packages/nextjs/src/server/clerkMiddleware.ts` around lines 171 - 176, Add
middleware test coverage for the auto-proxy opt-out branch in clerkMiddleware:
set CLERK_DISABLE_AUTO_PROXY=true, use a live publishable key and eligible
Vercel hostname, then assert the proxy handler is not invoked. Keep the test
focused on the condition guarded by isAutoProxyDisabledFromEnvironment and
preserve existing proxy behavior for other configurations.

Source: Coding guidelines

if (shouldAutoProxy(requestUrl.hostname)) {
frontendApiProxyConfig = { enabled: true };
}
Expand Down
11 changes: 11 additions & 0 deletions packages/nextjs/src/utils/__tests__/mergeNextClerkPropsWithEnv.test.ts
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Expand Up @@ -49,6 +49,17 @@ describe('mergeNextClerkPropsWithEnv', () => {
expect(result.proxyUrl).toBe('');
});

it('does not auto-derive proxyUrl when auto-proxy is disabled', () => {
process.env.CLERK_DISABLE_AUTO_PROXY = 'true';
process.env.NEXT_PUBLIC_CLERK_PUBLISHABLE_KEY = 'pk_live_Zm9vLmNsZXJrLmNvbSQ=';
process.env.VERCEL_TARGET_ENV = 'production';
process.env.VERCEL_PROJECT_PRODUCTION_URL = 'myapp.vercel.app';

const result = mergeNextClerkPropsWithEnv({});

expect(result.proxyUrl).toBe('');
});
Comment on lines +52 to +61

@coderabbitai coderabbitai Bot Jul 14, 2026

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🩺 Stability & Availability | 🟡 Minor | ⚡ Quick win

Keep environment-sensitive tests deterministic.

Both suites can inherit CLERK_DISABLE_AUTO_PROXY=true from the test runner, causing auto-proxy-enabled cases to fail. Clear or explicitly disable the variable in shared setup, and set it to true only in opt-out cases.

  • packages/nextjs/src/utils/__tests__/mergeNextClerkPropsWithEnv.test.ts#L52-L61: isolate the flag before tests expecting /__clerk.
  • packages/backend/src/tokens/__tests__/authenticateContext.test.ts#L305-L313: isolate the flag before tests expecting automatic proxy derivation.
🧰 Tools
🪛 Betterleaks (1.6.1)

[high] 54-54: Detected a Generic API Key, potentially exposing access to various services and sensitive operations.

(generic-api-key)

📍 Affects 2 files
  • packages/nextjs/src/utils/__tests__/mergeNextClerkPropsWithEnv.test.ts#L52-L61 (this comment)
  • packages/backend/src/tokens/__tests__/authenticateContext.test.ts#L305-L313
🤖 Prompt for AI Agents 
Verify each finding against current code. Fix only still-valid issues, skip the
rest with a brief reason, keep changes minimal, and validate.

In `@packages/nextjs/src/utils/__tests__/mergeNextClerkPropsWithEnv.test.ts`
around lines 52 - 61, Make the environment-sensitive tests deterministic by
clearing or explicitly disabling CLERK_DISABLE_AUTO_PROXY in shared setup for
auto-proxy-enabled cases, while setting it to true only in opt-out cases. Apply
this in packages/nextjs/src/utils/__tests__/mergeNextClerkPropsWithEnv.test.ts
at lines 52-61 and
packages/backend/src/tokens/__tests__/authenticateContext.test.ts at lines
305-313, preserving the existing expectations for /__clerk and automatic proxy
derivation.


it('does not override an explicit proxyUrl', () => {
process.env.NEXT_PUBLIC_CLERK_PUBLISHABLE_KEY = 'pk_live_Zm9vLmNsZXJrLmNvbSQ=';
process.env.VERCEL_TARGET_ENV = 'production';
Expand Down
13 changes: 13 additions & 0 deletions packages/shared/src/__tests__/proxy.spec.ts
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Expand Up @@ -116,6 +116,19 @@ describe('getAutoProxyUrlFromEnvironment(options)', () => {
).toBe('');
});

it('returns empty string when auto-proxy is disabled', () => {
expect(
getAutoProxyUrlFromEnvironment({
publishableKey: 'pk_live_Zm9vLmNsZXJrLmNvbSQ=',
environment: {
CLERK_DISABLE_AUTO_PROXY: 'true',
VERCEL_PROJECT_PRODUCTION_URL: 'myapp.vercel.app',
VERCEL_TARGET_ENV: 'production',
},
}),
).toBe('');
});

it('returns empty string for ineligible or non-production Vercel environments', () => {
expect(
getAutoProxyUrlFromEnvironment({
Expand Down
9 changes: 9 additions & 0 deletions packages/shared/src/proxy.ts
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@@ -1,4 +1,5 @@
import { isProductionFromPublishableKey } from './keys';
import { isTruthy } from './underscore';

/**
*
Expand Down Expand Up @@ -55,6 +56,10 @@ function getDefaultEnvironment(): NodeJS.ProcessEnv {
return typeof process !== 'undefined' && process.env ? process.env : {};
}

export function isAutoProxyDisabledFromEnvironment(environment = getDefaultEnvironment()): boolean {
return isTruthy(environment.CLERK_DISABLE_AUTO_PROXY);
}

function normalizeHostname(hostnameOrUrl: string): string {
if (hostnameOrUrl.startsWith('http://') || hostnameOrUrl.startsWith('https://')) {
try {
Expand Down Expand Up @@ -90,6 +95,10 @@ export function getAutoProxyUrlFromEnvironment({
return '';
}

if (isAutoProxyDisabledFromEnvironment(environment)) {
return '';
}

if (environment.VERCEL_TARGET_ENV !== 'production') {
return '';
}
Expand Down
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