Auth.js v5: Providers showing localhost:3000 instead of production domain when deployed to VPS with Dokploy

[subonedev]

To Reproduce

I'm having an issue with Auth.js (NextAuth) v5 in my Next.js application when deploying with Dokploy on my VPS server. The providers' URLs are showing localhost:3000 instead of my production domain.

Environment:

• Next.js 15
• Auth.js (NextAuth) v5
• Deployed using Dokploy
• Running behind Cloudflare proxy

Issue:

When I check the /api/auth/providers endpoint in production, it shows:

{
  "google": {
    "id": "google",
    "name": "Google",
    "type": "oidc",
    "signinUrl": "http://localhost:3000/api/auth/signin/google",
    "callbackUrl": "http://localhost:3000/api/auth/callback/google"
  }
}
Expected behavior:
The URLs should show my production domain instead of localhost:3000.


How can I make Auth.js use my production domain instead of localhost while avoiding the Cloudflare error?

ps: cloudflare set to FULL ssl/tls

### Current vs. Expected behavior

What I've tried:

Setting environment variables:

NEXT_PUBLIC_APP_URL=https://mydomain.com
AUTH_SECRET=[my-secret]
AUTH_TRUST_HOST=true

The same setup works correctly when deployed to Vercel, but fails on my VPS server deployment.
When I add AUTH_URL=https://mydomain.com to env in production:

The providers show the correct domain:

{
  "google": {
    "id": "google",
    "name": "Google",
    "type": "oidc",
    "signinUrl": "http://mydomain.com/api/auth/signin/google",
    "callbackUrl": "http://mydomain.com/api/auth/callback/google"
  }
}

BUT Cloudflare returns error 10000 on the homepage

### Provide environment information

```bash
NEXT_PUBLIC_APP_URL=https://mydomain.com
AUTH_SECRET=[my-secret]
AUTH_TRUST_HOST=true
AUTH_URL=https://mydomain.com

Which area(s) are affected? (Select all that apply)

Installation, Application, Traefik, Docker, Remote server

Are you deploying the applications where Dokploy is installed or on a remote server?

Remote server

Additional context

Ubuntu 22.04 LTC

Will you send a PR to fix it?

No