Docs for "Hosting on Vercel > Preview Deployments" no longer work

[mattrossman]

Checklist

• The issue can be reproduced in the nextjs-auth0 sample app (or N/A).
• I have looked into the Readme, Examples, and FAQ and have not found a suitable solution or answer.
• I have looked into the API documentation and have not found a suitable solution or answer.
• I have searched the issues and have not found a suitable solution or answer.
• I have searched the Auth0 Community forums and have not found a suitable solution or answer.
• I agree to the terms within the Auth0 Code of Conduct.

Description

The docs say that for Vercel Preview deployments you should set:

# .env.production
NEXT_PUBLIC_AUTH0_BASE_URL=$VERCEL_URL

(source)

When I do this, I get a 500 error saying that baseURL is required. Even though I can see that NEXT_PUBLIC_AUTH0_BASE_URL is correctly set in my logs, the library seems to not recognize it.

Additionally, the docs suggest that you can use $VERCEL_BRANCH_URL for branch preview URLs, however this variable is undefined and I can't find it mentioned in the Vercel System Environment Variables (perhaps deprecated?)

Reproduction

1. Clone sample app https://github.com/auth0-samples/auth0-nextjs-samples/tree/main/Sample-01
2. Assign "Preview" environment variables on Vercel, with exception of AUTH0_BASE_URL
3. Add .env.production file as shown above
4. Configure Auth0 to allow *.vercel.app callback URLs / logout URLs
5. npx vercel deploy and follow prompts
6. Open preview URL and attempt login

Additional context

If I change the .env.production file to set AUTH0_BASE_URL instead of NEXT_PUBLIC_AUTH0_BASE_URL then I can log in as expected (only on "commit" style preview URLs, not the branch preview URLs)

I'm not sure why this happens because this library appears to check both variables:

nextjs-auth0/src/config.ts

Line 492 in 5989b32

const AUTH0_BASE_URL = process.env.AUTH0_BASE_URL || process.env.NEXT_PUBLIC_AUTH0_BASE_URL;

Perhaps the environment variables behavior has changed in recent Next.js versions.

nextjs-auth0 version

2.5.0

Next.js version

13.4.1

Node.js version

18.16.0

[mattrossman]

Looks like this PR was very recent so maybe these docs are just ahead of the latest release? #1198

[adamjmcgrath]

Hi @mattrossman - thanks for raising this

Yep, I'll do a release of 2.6 today to catch up with those docs changes