mounted-dev must not re-create consoles in a container

Marking high priority because without this we cannot use separate /dev partitions in a container.

As per discussion on #ubuntu-devel, lxc should run MAKEDEV in the container before setting up its devices.

To do this, teh setup_autodev() function must be split up. We'll first mount all lxc filesystems (including a fresh /dev), then run MAKEDEV console in the container, then do the rest of setup_autodev() if lxc.autodev = 1.

Have talked through this with hallyn in detail.

 - we don't want to change MAKEDEV itself to not clobber existing device nodes, because in other cases this makes recovery from broken /dev less reliable
 - we can't side-step this by making /dev not be a mountpoint within the container because in some cases users want to use a read-only rootfs
 - we can't use devtmpfs instead because there is only *one* devtmpfs in the kernel no matter where it's mounted, so this would make it impossible to make the exact change to node targets that this is about.

So I'm convinced that the linked branch is an appropriate solution to this problem. It has no impact on the common case when /dev is a devtmpfs, we don't call MAKEDEV at all in that scenario.

... except that we can't actually call running-in-container reliably this early in the boot process; /run is not guaranteed to be mounted (or seen to be mounted) before /dev.

A lxc tree which is working for me to do MAKEDEV console in the container is at lp:~serge-hallyn/ubuntu/raring/lxc/lxc-makedev.

This bug was fixed in the package mountall - 2.45

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mountall (2.45) unstable; urgency=low

  [ Serge Hallyn ]
  * mounted-dev.conf: leave consoles alone in a lxc or libvirt container
    (LP: #1075717)

 -- Steve Langasek <email address hidden> Wed, 28 Nov 2012 22:07:18 -0800

This bug was fixed in the package lxc - 0.8.0~rc1-4ubuntu47

---------------
lxc (0.8.0~rc1-4ubuntu47) raring; urgency=low

  * 0230-autodev-makedev-console: Run MAKEDEV(console) before creating
    consoles in the container. This is to make up for the fact that
    userspace (i.e. mountall) won't be doing so, since it otherwise
    would overwrite the consoles set up by lxc. (LP: #1075717)
 -- Serge Hallyn <email address hidden> Wed, 28 Nov 2012 16:08:37 -0600

This needs fixing in precise too. I just ran into that very problem with current upstream LXC and a precise privileged container.

I'll upload a straight cherry-pick of the mounted-dev.conf job as we have it nowadays (I confirmed that fixes it here).

Hello Serge, or anyone else affected,

Accepted mountall into precise-proposed. The package will build now and be available at http://launchpad.net/ubuntu/+source/mountall/2.36.4ubuntu0.1 in a few hours, and then in the -proposed repository.

Please help us by testing this new package. See https://wiki.ubuntu.com/Testing/EnableProposed for documentation how to enable and use -proposed. Your feedback will aid us getting this update out to other Ubuntu users.

If this package fixes the bug for you, please add a comment to this bug, mentioning the version of the package you tested, and change the tag from verification-needed to verification-done. If it does not fix the bug for you, please add a comment stating that, and change the tag to verification-failed. In either case, details of your testing will help us make a better decision.

Further information regarding the verification process can be found at https://wiki.ubuntu.com/QATeam/PerformingSRUVerification . Thank you in advance!

Verified, with -proposed I now get a console in precise container, thanks.

The verification of the Stable Release Update for mountall has completed successfully and the package has now been released to -updates. Subsequently, the Ubuntu Stable Release Updates Team is being unsubscribed and will not receive messages about this bug report. In the event that you encounter a regression using the package from -updates please report a new bug using ubuntu-bug and tag the bug report regression-update so we can easily find any regressions.

This bug was fixed in the package mountall - 2.36.4ubuntu0.1

---------------
mountall (2.36.4ubuntu0.1) precise; urgency=medium

  * mounted-dev.conf: Don't mess with consoles inside containers. (LP: #1075717)
 -- Stephane Graber <email address hidden> Wed, 21 Jan 2015 13:04:17 -0500