feat: add configurable Horizon dashboard admin access

[SelimSalihovic]

Changes

Added support for HORIZON_ALLOWED_EMAILS environment variable to allow multiple users to access the Horizon dashboard. Previously, only the root user (User ID 0) could access /horizon. This change modifies the HorizonServiceProvider gate to check for a comma-separated list of email addresses in the new environment variable. Root user always retains access for backward compatibility.

Modified files:

• app/Providers/HorizonServiceProvider.php - Updated gate logic to check HORIZON_ALLOWED_EMAILS
• .env.development.example - Added documentation for new environment variable

Issues

• Fixes Allow configuring additional Horizon dashboard admins via environment variable #9351

Category

• New feature

Preview

Testing was performed in local development environment. Screenshots can be provided upon request showing non-root user accessing Horizon dashboard after setting HORIZON_ALLOWED_EMAILS.

AI Assistance

• AI was used (please describe below)

If AI was used:

• Tools used: Claude Code
• How extensively: AI assisted with implementation and PR creation. Code was reviewed and tested by human contributor.

Testing

Tested in local development environment:

1. Started development environment with spin up
2. Added HORIZON_ALLOWED_EMAILS=test@example.com to .env file
3. Restarted Horizon with: docker exec coolify php artisan horizon:terminate
4. Verified root user can access /horizon
5. Verified user in HORIZON_ALLOWED_EMAILS can access /horizon
6. Verified unauthorized user gets 403 Forbidden
7. Verified backward compatibility by removing env var - only root user retained access

Contributor Agreement

Important

• I have read and understood the contributor guidelines. If I have failed to follow any guideline, I understand that this PR may be closed without review.
• I have searched existing issues and pull requests (including closed ones) to ensure this isn't a duplicate.
• I have tested all the changes thoroughly with a local development instance of Coolify and I am confident that they will work as expected when a maintainer tests them.