Date: Wed, 7 Nov 2007 13:17:01 -0800 From: Christopher Cowart <ccowart@rescomp.berkeley.edu> To: freebsd-rc@freebsd.org Subject: Re: Multiple instances of a daemon Message-ID: <20071107211701.GP65098@hal.rescomp.berkeley.edu> In-Reply-To: <20071107084803.6a3564db.wmoran@collaborativefusion.com> References: <20071107082837.GM65098@hal.rescomp.berkeley.edu> <20071107084803.6a3564db.wmoran@collaborativefusion.com>
next in thread | previous in thread | raw e-mail | index | archive | help
--Pr8rMdbFBWzrOzFq
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
Content-Transfer-Encoding: quoted-printable
On Wed, Nov 07, 2007 at 08:48:03AM -0500, Bill Moran wrote:
>In response to Christopher Cowart <ccowart@rescomp.berkeley.edu>:
>> Hello,
>>=20
>> I want to be able to use the same rc script to start several instances
>> of a daemon. When I've encountered this desire before, I've cp'd the
>> script, given it a unique name, and carried on with my business. This is
>> a but kludgy and makes updating scripts a manual task.
>>=20
>> Today, I realized the arpd port didn't provide an rc script, so I set
>> out to write one. I also knew that I was going to be launching several
>> different arpd's, so I wanted to figure out a better way to deal with
>> this problem.
>>=20
>> I thought I'd be clever and use symlinks:
>> rc.d $ ls -l arpd*
>> -r-xr-xr-x 1 root wheel 486 Nov 7 00:01 arpd
>> lrwxr-xr-x 1 root wheel 4 Nov 6 23:32 arpd_vlan665 -> arpd
>> lrwxr-xr-x 1 root wheel 4 Nov 6 23:32 arpd_vlan679 -> arpd
>>=20
>> Then I wrote my rc script with `name=3D${0##*/}'. Everything was fantast=
ic
>> doing manual starts and stops. Then I tried rebooting...
>>=20
>> After a few boots, some debugging, and a lot of tracing through /etc/rc
>> and /etc/rc.subr, I found the problem (or is it a feature?).
>> run_rc_script() sources the script. All the talk about not sourcing the
>> "current shell" anymore, and I foolishly assumed that meant something
>> more like calling the script and less like sourcing it in a subshell.
>>=20
>> I would really find it convenient to use the symlink trick shown above,
>> because it means a symlink-compatible rc-script can be updated by the
>> port or mergemaster, and all the "copies" will "just work." I'd be
>> willing to take the time to implement something, but I don't pretend=20
>> to know all the use cases or the motivation behind this design.=20
>>=20
>> One approach could be that run_rc_script() throws the rc script name
>> into a variable visible to the sourced script, say _rc_script_name.=20
>> Then name could be something like `${_rc_script_name:-${0##*/}}' or a
>> less terse if/then.
>>=20
>> Is this a feature other people would like to see, or is it just me?
>
>The canonical way of doing this has been a "profiles"-enabled rc
>script. See the Apache or Slony rc scripts for examples.
>
>Not sure if your approach might be better.
The jail rc script takes a smilar approach. It seems like when somebody
wants to "profile" their script, they have to write the logic from
scratch (or copy, paste, and tweak). Would a better solution be to=20
provide some default notion of profiling in the rc.subr library so rc=20
scripts can take advantage of it by default?=20
--=20
Chris Cowart
Lead Systems Administrator
Network & Infrastructure Services, RSSP-IT
UC Berkeley
--Pr8rMdbFBWzrOzFq
Content-Type: application/pgp-signature
Content-Disposition: inline
-----BEGIN PGP SIGNATURE-----
Version: GnuPG v2.0.4 (FreeBSD)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=S3q8
-----END PGP SIGNATURE-----
--Pr8rMdbFBWzrOzFq--
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?20071107211701.GP65098>