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From: ludo@gnu.org (Ludovic =?utf-8?Q?Court=C3=A8s?=)
Subject: Re: Daemon: nix-connection-error
Date: Mon, 24 Jun 2013 01:05:36 +0200
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To: Nikita Karetnikov <nikita@karetnikov.org>
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Nikita Karetnikov <nikita@karetnikov.org> skribis:

>> Ah, so this was not the log of a chroot build, right?  (There=E2=80=99s =
no
>> /homeless-shelter directory in the chroot.)
>
> I'm puzzled.  The manual says that "each build process is run in a
> chroot environment." [1]  However, I see
>
> export HOME=3D"/homeless-shelter"
>
> in '/tmp/nix-build-coreutils-8.21.drv-7/environment-variables'.
>
> Is anything wrong with Guix, or is it my fault?

What makes you think there=E2=80=99s a contradiction here?

Turns out $HOME is automatically set by the daemon for each build (from
nix/libstore/build.cc):

    /* Set HOME to a non-existing path to prevent certain programs from usi=
ng
       /etc/passwd (or NIS, or whatever) to locate the home directory (for
       example, wget looks for ~/.wgetrc).  I.e., these tools use /etc/pass=
wd
       if HOME is not set, but they will just assume that the settings file
       they are looking for does not exist if HOME is set but points to some
       non-existing path. */
    Path homeDir =3D "/homeless-shelter";
    env["HOME"] =3D homeDir;

Yet, the daemon runs builds in a chroot, or complains if it cannot for
some reason (unless HAVE_CHROOT is unset.)

Can you check that HAVE_CHROOT is set, and that the build users exist?

>> Not sure what --userspec is.
>
> 'chroot --userspec=3DUSER:GROUP' allows to specify a user and a group.

And what would you do with that?

As explained in the manual, the normal setup is to run the daemon as
root with --build-users-group; it then automatically calls chroot(2) and
seteuid(2) in the child processes that run the builds.

HTH,
Ludo=E2=80=99.