Bug#222047: --configure should process essential packages first
Package: dpkg
Version: 1.10.18
Currently if more unconfigured packages are being configured, their
ordered is determined by the Depends fields of the packages, however, the
Essential field is not taken into account, hence it might (and actually
does) occur that a non-essential package is configured earlier than an
essential one.
This behaviour is against the policy that AFAIK essential packages
required by a certain package do not need to be explicitely mentioned in
the Depends field. Just one example: on a Debian 3.0 system nscd only
depends on libc6, even if its startup script requires bash, shellutils
(uname), grep and dpkg (start-stop-daemon), but these are all essential
packages.
On a dpkg based (but not Debian) system I have a script that builds up a
chroot system: it unpacks all the required .deb files to a directory, and
later it runs "dpkg --root=... --configure -a". In most of the cases it
runs perfectly. However, I've met the following interesting situation:
building up the chroot failed if I put postgresql-server amongst the
packages. postgresql-server invokes a "su -c command otheruser" command in
its postinst script. However, su requires valid basic configuration, which
isn't available as long as shadow (and possibly some other essential)
packages are unconfigured (e.g. /etc/shells might not yet be present). The
"dpkg --configure -a" step just randomly chose to configure
postgresql-server earlier than shadow, and hence it failed. Obviously
making postgresql-server depend on shadow solved the problem, but since
shadow is an essential package, I expect that it shouldn't be necessary to
mention it in postgresql-server's Depends field, I think the postinst
script of a non-essential package could expect that essential packages are
already configured.
So whenever more packages are being configured, essential ones should be
processed first, before any non-essential ones.
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