AlmaLinux 9 network-scripts migration to NetworkManager keyfiles

AlmaLinux 9 fully deprecates the legacy network-scripts package, shifting network management from shell scripts in /etc/sysconfig/network-scripts/ to INI-based keyfiles located in /etc/NetworkManager/system-connections/. While nmcli serves as the primary interface for modern configurations, legacy environments relying on custom routing logic or ifup commands face compatibility boundaries.

The network service is no longer present by default, and manual migration of legacy files does not guarantee active configurations without explicit conversion to the keyfile format. There is specific uncertainty regarding how the system handles custom routing scripts that do not conform to the modern NetworkManager plugin architecture during future minor release updates.

• How should custom routing logic be refactored when it cannot be converted into a standard NetworkManager dispatcher script?
• Is there a documented mechanism to ensure that manually created keyfiles are correctly parsed and applied without being ignored by the NetworkManager daemon?