->>There is no description about what the abstraction layer should be. What basic functions are there for an NTP server and how does each server map into that abstraction? What basic methods are required?

An abstract module is the parent basentpconf module, which contains the base ntp classes for the server and the client, from which ntpdlib, ontpdlib, and chronylib are inherited. The parent client and server classes contain methods for configuring, synchronizing, and restoring the initial state of the ntp server. It uses common functions from ntpmethods. As for ntpdlib, ontpdlib, and chronylib, they contain classes for configuring their ntp server directly, inherited from basentpconf, and override the desired properties.

->>Do all servers support the options server and pool?

All the ntp servers listed here support the server and pool options, the values ​​of which are written to the configuration file with the appropriate field.

->>How will dependencies be managed? Is there a common way to do this with both Fedora-like and Debian-like distributions?

Each package with freeipa ntp lib contains a dependency on the ntp server that it uses. To use freeipa ntp lib, it is enough to install a package with an appropriate ntp server.

->>Is it an error if no NTP servers are installed? Is this what is meant by "default ntp configuration"? Is that functionally equivalent to "no NTP service is configured"?

If the system does not detect the ntp server, and the user does not use the option '--no-ntp', then the installation of freeipa will end with information about this. If the ntp server or ntp pool options are not specified by the user, then the ntp server is set by default, that is, configured on the basis of the ntp server that was laid down.

->>Could there be service-specific options that would need to be passed or set?

You can set options for the ntp service such as ntp pool and ntp server.

->>How will this impact testing? Will all possible options need to be tested or is spot-checking or a single server adequate?

For testing, it is necessary to start the installation of freeipa both with the --ntp-server and --ntp-pool options, and without them, on all supported time servers.

->>Will backup/restore need to be extended to pick up the service-specific files?

For backup and restore, standard freeipa methods are used, which are used to preserve the original state of the service and the configuration file. After freeipa is removed, the service is restored to its original state. To do this, freeipa ntp using the createntp.uninstall_client and createntp.uninstall_server methods for the client and server, respectively.

->>Upon restore there will need to be some sort of check that the required NTP service is installed which means that the service needs to be recorded somewhere.

If another ntp service is installed, the service will not be restored, since the required service will not be available in the system.