Configure jail in /etc/jail.my-jail-name.conf while allowing auto-start with "service jail start"

[Andreas Sommer]

Hi all,

as I can see, this combination simply isn't part of /etc/rc.d/jail and jail(8).
In fact, jail(8) always only reads one config file (`-f` parameter, default
/etc/jail.conf).

This also relates to why ezjail was still not ported to use jail.conf [0][1].

It would be a great fit to automated configuration management (e.g. via Ansible
or pkg POST-INSTALL scripts) because it allows overwriting complete files
instead of having to edit the global jail.conf to make changes.

Jail configured only in /etc/jail.my-jail-name.conf:

> # service jail onestart
> Starting jails:.
(nothing started because jail not recognized as configured)

Jail configured in /etc/jail.my-jail-name.conf and "mentioned" as
`jail my-jail-name {}` in /etc/jail.conf:

> # service jail onestart
> Starting jails:jail: my-jail-name: new jail must persist or attach
(this means only /etc/jail.conf was parsed)

Any way to achieve this? I assume the answer is no, so here's a suggestion:
what about having jail(8) read/merge configuration from another file?

Example:
> # cat /etc/jail.conf
> my-jail-name { config = "/etc/jail.my-jail-name.conf"; }
> # cat /etc/jail.my-jail-name.conf
> my-jail-name { ...config goes here... }

Thanks,
 Andreas

[0] https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=218849
[1] https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=218849#c13 (ezjail maintainer comment)