For LXC systems all mounts are supposed to happen _before_
init is run. Every mount tried by one of the run level scripts
creates a "permission denied" error message.

Below is a sample boot session showing startup and shutdown
of a LXC system (CONCURRENCY=none).

The problem is that I cannot disable the "unwanted" scripts
performing the mount, because I would loose other initialization
steps as well.

It would be very nice if the run level scripts doing mount/\
umount could be streamlined to support LXC systems.


Many thanx
Harri
-------------------------------------------------------------------
# lxc-start -n wheezy
INIT: version 2.88 booting
@@@ /etc/rcS.d/S01checkroot-bootclean.sh start
Cleaning up temporary files... /tmp /lib/init/rw /run /run/lock /run/shm.
@@@ /etc/rcS.d/S01mountkernfs.sh start
mount: permission denied
mount: permission denied
@@@ /etc/rcS.d/S01mtab.sh start
mount: permission denied
mount: permission denied
mount: permission denied
Mount point '/dev/console' does not exist. Skipping mount. ... (warning).
Mount point '/dev/tty1' does not exist. Skipping mount. ... (warning).
Mount point '/dev/tty2' does not exist. Skipping mount. ... (warning).
Mount point '/dev/tty3' does not exist. Skipping mount. ... (warning).
Mount point '/dev/tty4' does not exist. Skipping mount. ... (warning).
Mount point '/dev/ptmx' does not exist. Skipping mount. ... (warning).
@@@ /etc/rcS.d/S02mountdevsubfs.sh start
mount: permission denied
@@@ /etc/rcS.d/S03bootlogd start
@@@ /etc/rcS.d/S04checkfs.sh start
Activating lvm and md swap...done.
Checking file systems...fsck from util-linux 2.20.1
done.
@@@ /etc/rcS.d/S05hostname.sh start
hostname: you must be root to change the host name
@@@ /etc/rcS.d/S05mountall.sh start
Mounting local filesystems...done.
/etc/rcS.d/S05mountall.sh: 59: kill: Illegal number: 2 1
Activating swapfile swap...done.
mount: permission denied
mount: permission denied
mount: permission denied
@@@ /etc/rcS.d/S06mountall-bootclean.sh start
Cleaning up temporary files....
@@@ /etc/rcS.d/S07procps start
Setting kernel variables ...done.
@@@ /etc/rcS.d/S07resolvconf start
Setting up resolvconf...done.
@@@ /etc/rcS.d/S07urandom start
@@@ /etc/rcS.d/S08networking start
Configuring network interfaces...Internet Systems Consortium DHCP Client 4.2.2
Copyright 2004-2011 Internet Systems Consortium.
All rights reserved.
For info, please visit https://www.isc.org/software/dhcp/

Listening on LPF/eth0/00:20:82:75:b6:ef
Sending on   LPF/eth0/00:20:82:75:b6:ef
Sending on   Socket/fallback
DHCPDISCOVER on eth0 to 255.255.255.255 port 67 interval 4
DHCPREQUEST on eth0 to 255.255.255.255 port 67
DHCPOFFER from 172.19.96.123
DHCPACK from 172.19.96.123
bound to 172.19.99.214 -- renewal in 885 seconds.
done.
@@@ /etc/rcS.d/S09mountnfs.sh start
@@@ /etc/rcS.d/S10mountnfs-bootclean.sh start
Cleaning up temporary files....
@@@ /etc/rcS.d/S11bootmisc.sh start
@@@ /etc/rcS.d/S12stop-bootlogd-single start
INIT: Entering runlevel: 3
@@@ /etc/rc3.d/S01bootlogs start
@@@ /etc/rc3.d/S01motd start
@@@ /etc/rc3.d/S01rsyslog start
Starting enhanced syslogd: rsyslogd.
@@@ /etc/rc3.d/S02cron start
Starting periodic command scheduler: cron.
@@@ /etc/rc3.d/S02rsync start
@@@ /etc/rc3.d/S02ssh start
Starting OpenBSD Secure Shell server: sshd.
@@@ /etc/rc3.d/S03rc.local start
@@@ /etc/rc3.d/S03rmnologin start
@@@ /etc/rc3.d/S03stop-bootlogd start

Debian GNU/Linux 7.0 wheezy.vs.aixigo.de console

INIT: Switching to runlevel: 0
INIT: Sending processes the TERM signal
@@@ /etc/rc0.d/K01resolvconf stop
Stopping resolvconf...done.
@@@ /etc/rc0.d/K01sendsigs stop
Asking all remaining processes to terminate...done.
All processes ended within 1 seconds...done.
@@@ /etc/rc0.d/K01urandom stop
@@@ /etc/rc0.d/K02rsyslog stop
Stopping enhanced syslogd: rsyslogd.
@@@ /etc/rc0.d/K03umountnfs.sh stop
umount: /dev/ptmx: must be superuser to umount
umount: /dev/tty4: must be superuser to umount
umount: /dev/tty3: must be superuser to umount
umount: /dev/tty2: must be superuser to umount
umount: /dev/tty1: must be superuser to umount
umount: /dev/console: must be superuser to umount
@@@ /etc/rc0.d/K04networking stop
Deconfiguring network interfaces...Internet Systems Consortium DHCP Client 4.2.2
Copyright 2004-2011 Internet Systems Consortium.
All rights reserved.
For info, please visit https://www.isc.org/software/dhcp/

Listening on LPF/eth0/00:20:82:75:b6:ef
Sending on   LPF/eth0/00:20:82:75:b6:ef
Sending on   Socket/fallback
DHCPRELEASE on eth0 to 172.19.96.123 port 67
done.
@@@ /etc/rc0.d/K05umountfs stop
Unmounting temporary filesystems...umount: /lib/init/rw: must be superuser to umount
failed.
Deactivating swap...swapoff: Not superuser.
failed.
@@@ /etc/rc0.d/K06umountroot stop
mount: permission denied
@@@ /etc/rc0.d/K07halt stop
Will now halt.
INIT: no more processes left in this runlevel

If the scripts should be no-ops when lxc is in use, then this
should be fairly straightforward to cater for.  How do we detect
unambigiously if lxc is in use?

I'll be happy to review any apply any patches which improve lxc
support.


Thanks,
Roger

I strongly recommend a more generic approach of detecting whether the
required mount is already mounted, and skipping the operation if it is.

This has two advantages:

 - this isn't specific to lxc, but will correctly handle any other
   (theoretical) cases where the mounts are handled prior to initscripts.
 - if the lxc environment doesn't match the initscripts expectations, there
   will still be a suitable error message at boot about the failure to mount
   any mounts that are missing.

There is the non-obvious, and quite vexing issue of mount options.

Non-obvious, but it did occur to me as I was writing this comment because of
a related bug in Ubuntu about failing to remount initramfs-mounted
filesystems with the mount options specified in /etc/fstab.

I think it doesn't actually impact the correct design here.  Either your
mount does have a compatible set of mount options, in which case you don't
need to do anything; or it doesn't, in which case a remount is the correct
course of action and if it fails, it fails.  The proper course of action for
the admin in the case of a mismatch is the same, no matter how this is
handled within the lxc environment - it needs to be fixed in the
configuration outside the container.