Re: service jails and precmd make ntpd (and nfsd) sad

Alexander Leidinger <[email protected]> Sat, 22 Mar 2025 19:12:50 +0100
Newsgroups	gmane.os.freebsd.architechture
Organization	No organization, this is a private message.
Message-ID	<[email protected]>
Am 2025-03-21 15:52, schrieb Lexi Winter:
> Alexander Leidinger:
>> > i would propose 'setup' as the thing which is run outside the jail, and
>> > 'precmd' as the thing which is run inside the jail.
> 
>> Modifying the service jails to run the precmd (or whatever) inside 
>> instead
>> of of outside requires more than an one line change. Be careful if you 
>> want
>> to go that way.
> 
> i think this is going to break things either way.  i'd be fine with
> doing it the other way around, i.e., 'setup' runs inside the jail and
> 'precmd' runs outside the jail, but both nfsd and ntpd will need
> changing either way.

I did not want to suggest which name to use for inside or outside (the 
name matters, but right here, right now, for my point, it doesn't). I 
simply wanted to suggest that it may be more easy to check if there is a 
way without a change. For those scripts which I had to modify to make 
the work better with service jails, I didn't need to run a setup command 
in the jail, or I was able to integrate it into a start function.

>> There is another option. Load the kernel module outside of the ntpd 
>> service
>> rc script. Either as a documented requirement when enabling service 
>> jails
>> (and an error message from the rc script in the svcj case if the 
>> module is
>> not loaded), or by adding another rc script which also listens on
>> ntpd_enable and the ntpd rc scripts depends on.
> 
> some rc.d scripts (nfsd, for example) also attempt to set sysctls in
> their precmd, and this won't be allowed in a jail either.  would you
> suggest that all such services should have a second service 
> (ntpd_setup,
> nfsd_setup, etc.) to perform these tasks?
> 
> i'm not opposed to that approach, and i can see how it's cleaner, but
> before i put any effort into implementing it i'd appreciate some sort
> of consensus that this is the right approach.

In general: There are benefits both ways. Which one is cleaner... 
depends. Here I would not use xxx_setup, I would use xxx_kld. A setup 
you may want to run multiple times, or only once in total, or after 
every reboot (depending on what is setup and how). Something which loads 
klds needs to run before the securelevel is raised to >=1, whereas not 
everything which needs a kld needs to be started before the securelevel 
is raised (it might be started before, but not because of the 
securelevel).

I can also imagine a generic kld loader for services which checks for a 
particular meta-comment in the rc scripts and loads all klds specified 
in one go. That way we wouldn't need to load klds in each service. That 
could be realized as a rc script itself.

Bye,
Alexander.

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