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Date:      Sun, 8 May 2011 17:54:32 -0400
From:      Jason Hellenthal <jhell@DataIX.net>
To:        Devin Teske <dteske@vicor.com>
Cc:        Garrett Cooper <yanegomi@gmail.com>, freebsd-rc@freebsd.org
Subject:   Re: [RFC][Change-Request] Create usefulness in rc.subr etc/rc.conf.d/*.conf namespace.
Message-ID:  <20110508215432.GG3527@DataIX.net>
In-Reply-To: <5474DF9C-500A-4B51-948F-F56A66051476@vicor.com>
References:  <20110508191336.GC3527@DataIX.net> <C7EC90A2-936C-44E1-BC5E-E249399AF9AB@gmail.com> <5474DF9C-500A-4B51-948F-F56A66051476@vicor.com>

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Devin,

On Sun, May 08, 2011 at 01:59:40PM -0700, Devin Teske wrote:
>=20
> On May 8, 2011, at 1:13 PM, Garrett Cooper wrote:
>=20
> > On May 8, 2011, at 12:13 PM, Jason Hellenthal wrote:
> >=20
> >>=20
> >> List, - Please reply-to freebsd-rc@freebsd.org
> >>=20
> >> Recently I have been going over some changes in the configurations tha=
t=20
> >> are possible with the rc subsystem and to my dismay I have found some=
=20
> >> inconsistencies with in particular the way rc.conf.d directory is=20
> >> processed and the arguments that are supplied to load_rc_config so I h=
ave=20
> >> patched it up...
> >>=20
> >> Let me explain:  As determined by rc.subr load_rc_config, config's fro=
m=20
> >> rc.conf.d are loaded by the scripts $name as an argument to load_rc_co=
nfig=20
> >> and thus only the name being parsed is is available to be used in the=
=20
> >> rc.conf.d directory. Why is this bad ? Its not! but it is inconvenient=
 as=20
> >> the user has no direct way to know that a variable used by nfsd is als=
o=20
> >> needed by mountd or the same for various other scripts in the rc.d=20
> >> directory. At this time these config's are explained to be available f=
or=20
> >> the user to utilize by rc.conf(5) but yet without much knowledge of th=
e=20
> >> inner workings of the rc subsystem it would be quite the feat to do.
> >>=20
> >>=20
> >> The attachment[1] keeps this functionality the same while introducing =
a=20
> >> more convenient approach for the user to modularize their configuratio=
n=20
> >> however they see fit within a couple constraints that work very well.=
=20
> >>=20
> >>=20
> >> What does it do ?: As stated above, current functionality is undisturb=
ed=20
> >> while allowing the user to create config's by any name they so desire =
as=20
> >> long as it has an extension of ".conf", also introducing the ability t=
o=20
> >> turn a configuration file off by using chmod(1). You can turn nfsc1.co=
nf
> >> off/on by simply chmod [-/+]x etc/rc.conf.d/nfs1.conf
> >>=20
> >>=20
> >> Why ? Simple. How many times have you been bitten by disabling somethi=
ng=20
> >> in the rc.conf file and left to discover what you just disabled was al=
so=20
> >> used by another daemon but that daemon is now not starting ? This is a=
 way=20
> >> to virtualize your configuration allowing you to add multiple _enable=
=3D=20
> >> lines to different configurations for different roles. For instance=20
> >> rpcbind is used by both samba and nfs*. With this you can add=20
> >> rpcbind_enable to both a configuration for samba and nfs and when you=
=20
> >> disable one service you know that you have not disabled a dependent fo=
r=20
> >> another.
> >>=20
> >>=20
> >> This is a small addition that fixes currently broken undesirable aspec=
ts=20
> >> of the configuration system that deals with the rc.conf.d directory wi=
th a=20
> >> SysV style init approach that is just as flexible. This should apply=
=20
> >> cleanly to current and stable/8 & 8.2-RELEASE systems. Once more feedb=
ack=20
> >> has been received Ill update the manual page with any suggestions=20
> >> regenerate the patch to accommodate and file a PR.
> >>=20
> >>=20
> >> 1). http://patches.jhell.googlecode.com/hg/rc.subr_modular_conf.patch
> >=20
> > 	Doing:
> >=20
> > find /etc/rc.conf.d/ -type f -name '*.conf' -mindepth 1 -maxdepth 1 -pe=
rm +111 | while read _modular_conf; do
> > 	debug "Sourcing $_modular_conf"
> > 	. "$_modular_conf"
> > done
> >=20
> > 	might be better. There's some more magic that could ultimately be done=
 to make this more secure/robust using "-print0" | xargs, but it's up to yo=
u how you might want to go about solving that problem.
> > 	Also, I don't know if depending on a .conf file to be executable is ne=
cessarily the best course of action.
> >=20
>=20
> First, let me add that I really like the idea. This makes it akin to our =
/usr/local/apache2/conf.d/ directory where we place our various configs by =
many names, but always ending in `.conf'.
>=20
> I'm anticipating the day where I can have /etc/rc.d/foo.conf and /etc/rc.=
d/bar.conf, each configuring multiple (likely unrelated) services.
>=20
> Better still, /etc/rc.d/jail1.conf, /etc/rc.d/jail2.conf, etc. etc. (I th=
ink you just made my -- and everyone else whom uses jails -- day/week/month=
/year).
>=20
> However, I agree with GC that depending on a .conf file to be executable =
is a bit non-standard, even if it is sourced like a shell-script (though I =
can understand the historical heritage as /usr/local/etc/rc.d/ used to requ=
ire both `.sh' suffix and executable bits; but that is not to condone treat=
ing `rc.conf.d' like `rc.d' in any way).
>

I do agree with the -x bit concern yes. But thinking of the users to=20
enable disable a particular config without having to open a editor is=20
mainly why I have put that in place. It allows a lot of flexibility without=
=20
a lot of extra work while also introducing the ability to check if a=20
particular configuration is enabled by checking the bit rather than=20
sourcing for a _enable.

Since these are only config files there will/should never be a=20
config_enable for them as they are only config's, so providing a SysV init=
=20
style way of enabling/disabling them at will is prime. using mv(1), rm(1)=
=20
or possibly having to open a editor on multiple versions of the same=20
config to disable a certain portion is far from ideal.

I really don't want to see the rc system subjected to a find(1) every time=
=20
it needs to do a load_rc_config since it can be done quicker with in-shell=
=20
testing. I think a lot of people would agree with this.

I would suggest at least for those that doubt the SysV style way of=20
enabling disabling scripts give it a try for a couple weeks then report=20
back. If feed back is strong discouraging it then we can probably come to=
=20
common ground and find a way to work with both those who would like it and=
=20
those who don't by default. I do have a pretty good idea what would work=20
to make it happen both ways but I really would like to advocate this in=20
place as it is now first.


Thanks you again Devin, Appreciate the feedback.

--=20

 Regards, (jhell)
 Jason Hellenthal


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