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Date:      Wed, 26 Aug 2020 11:39:17 -0500
From:      Valeri Galtsev <galtsev@kicp.uchicago.edu>
To:        Matthew Seaman <matthew@FreeBSD.org>
Cc:        freebsd-questions@freebsd.org
Subject:   Re: Jail question: packages with relative symlinks
Message-ID:  <5E7E9966-E534-407E-B5DB-A45878760FA0@kicp.uchicago.edu>
In-Reply-To: <2eb62151-38b5-5e63-43a1-5cac1967b681@FreeBSD.org>
References:  <f3636f36-b6ce-3e8a-878a-bf8d5f75144d@kicp.uchicago.edu> <24d244da-43e4-9a5e-e940-3f183bc5a50e@holgerdanske.com> <9127e9ca-c6be-d007-bd82-fdf7c5508242@kicp.uchicago.edu> <7c3ad6a6-5ff1-5816-dc23-83d80590baac@kicp.uchicago.edu> <2eb62151-38b5-5e63-43a1-5cac1967b681@FreeBSD.org>

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> On Aug 26, 2020, at 11:28 AM, Matthew Seaman <matthew@FreeBSD.org> =
wrote:
>=20
> On 25/08/2020 22:30, Valeri Galtsev wrote:
>> I probably didn't explain things detailed enough.
>>=20
>> my jail has its root in:
>>=20
>> /jail/[jailname]
>>=20
>> so all what is inside jail on host filesystem is visible as:
>>=20
>> /jail/[jailname]/s/etc
>> /jail/[jailname]/etc --> s/etc
>> /jail/[jailname]/usr
>> /jail/[jailname]/s/usr-local
>> /jail/[jailname]/usr/local --> ../s/usr-local
>> ...
>>=20
>> the
>>=20
>> /jail/[jailname]
>>=20
>> is base system mounted read-only (with symlinks etc pointing to =
s/etc,
>> and others which point to a single place
>>=20
>> /jail/[jailname]/s
>>=20
>> which is mounted read-write, and this is the only place inside jail
>> which  is read-write. This is the wonderful idea which inside jail =
makes
>> base system read-only. And it is convenient, as you maintain only one
>> base system (of given version) for all jails. And as you correctly =
said,
>> chroot is used (in addition to other things), so inside jail what on
>> host is /jail/[jailname]/ is plainly /
>>=20
>> I hope, this provides enough detail to un-confuse things (and the =
need
>> of symlinks when one sets up jails "by the book", meaning FreeBSD =
Handbook)
>>=20
>> Valeri
>=20
> There's a '--relocate' flag to pkg-add(8) which almost does what you
> want.  The idea is that it allows you to prepend an arbitrary path to
> the location where the package is installed.  In your case, that would
> mean running
>=20
> pkg add --relocate /jail/[jailname]  some-package
>=20

Matthew, thanks for a nice idea! It has never occurred to me. Basically, =
as package is installed by executing pkg command in jail, pkg already =
sees /jail/[jailname] as / , but as I care of symlinks, and all writable =
is in jail mounted as /s/ , relocation of that package to /s may do the =
trick. I will check that, and will report if it solves my case, I just =
could not hold myself and answered now being this excited by idea that =
looks so simple so it is next to genius, and which never occurred to =
me=E2=80=A6

Valeri

> However I'm not sure how well that works for installing the same =
package
> in several different jails, or in your jail and in the host system --
> you might need to play games with using several different $PKG_DBDIR =
setups.
>=20
> Also, it only works with pkg-add(8), not pkg-install(8) or
> pkg-upgrade(8).  It is an experimental feature intended for use in
> cross-installing packages for a small appliance by mounting its drive
> onto a larger and more capable machine.
>=20
> 	Cheers,
>=20
> 	Matthew
>=20
> =09
>=20




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