- Add detect_package_manager() function that prefers 'apt' over 'apt-get'
- Use PKG_MANAGER variables throughout script for consistency
- Support both modern Debian 13+ (apt) and older systems (apt-get)
- Automatically detect and use the best available package manager
- Better error handling when no package manager is found
Fixes compatibility with:
- Debian 13 (Trixie) and newer
- Ubuntu 22.04+ (prefers apt)
- Older Debian/Ubuntu systems (fallback to apt-get)
All package operations now use the detected package manager:
- System updates and upgrades
- Prerequisites installation
- Node.js, PostgreSQL, nginx, certbot installation
- Add root permission check at startup
- Install sudo automatically if not present (for Debian systems)
- Add run_as_user() helper function with better error handling
- Provide fallback PostgreSQL setup using 'su' when sudo unavailable
- Replace all sudo -u commands with the new helper function
- Better error messages for missing users/sudo
This ensures compatibility with minimal Debian systems that don't have sudo by default.
- Detect when FQDN starts with digit (IP address)
- Generate 2 random letter prefix for database/service names
- Use prefixed names for DB_NAME, DB_USER, INSTANCE_USER
- Keep original FQDN for nginx configs and URLs
- Prevents PostgreSQL errors with numeric database names
Example: 192.168.1.50 -> xy192_168_1_50 for services
