Include directive to support "conf.d/*" and the like

[Kalin KOZHUHAROV]

On Fri, Mar 16, 2018 at 9:02 AM, Roman Mamedov <rm.wg at romanrm.net> wrote:
> I would like to be able to split the [Interface] and [Peer] parts of the config
> file into separate files. The reason is that currently I manage configurations
> of my various hosts at a central location, then push out common configs to all
> hosts.
>
BTW, this is the default in Gentoo at the moment... e.g.
# fgrep wg49 /etc/conf.d/net
/etc/conf.d/net:config_wg49="10.1.8.1/16"
/etc/conf.d/net:wireguard_wg49="/etc/wireguard/wg49.conf"

... and I often hate it :-)
In a way it is in a way "include", basically IP address and additional
routing is configured as with any other interface, but WG specific
part (ListenPort,PrivateKey,PublicKey,AllowedIPs,Endpoint) in another,
_interface_specific_ file...

This currently seems to make impossible to use standard
`/etc/init.d/net.wg?? start|stop` mechanism along `wg-quick` commands
(e.g. Address cannot be specified in "/etc/wireguard/wg49.conf").

There was somewhat related discussion few months ago about the
difference between configuration and state (`running config` as Cisco
names it) and them being somewhat mixed.

I guess this part may need reworking, but that should involve at least
a few distributions with a few subsystems (e.g. initrc and systemd
alonng wg-quick) that may be incompatible, so it is a hard task.

Cheers,
Kalin.