Regression: "lxc-create -B best" stopped working

[Martin Pitt]

I want to use btrfs storage if available, otherwise the plain old directory/copies. Until not too long ago, this worked:

  $ sudo lxc-create -B best --name=adt-xenial -t ubuntu -- -r xenial

But now in final xenial it fails with "best is not a valid backing storage type.".

But the manpage still documents it:

              If backingstore is 'best', then lxc will try, in order, btrfs, zfs, lvm, and finally a di‐
              rectory backing store.

ProblemType: Bug
DistroRelease: Ubuntu 16.04
Package: lxc 2.0.0-0ubuntu2
ProcVersionSignature: Ubuntu 4.4.0-21.37-generic 4.4.6
Uname: Linux 4.4.0-21-generic x86_64
ApportVersion: 2.20.1-0ubuntu2
Architecture: amd64
CurrentDesktop: i3
Date: Tue Apr 26 08:33:14 2016
EcryptfsInUse: Yes
PackageArchitecture: all
SourcePackage: lxc
UpgradeStatus: No upgrade log present (probably fresh install)
defaults.conf:
 lxc.network.type = veth
 lxc.network.link = lxcbr0
 lxc.network.flags = up
 lxc.network.hwaddr = 00:16:3e:xx:xx:xx
dnsmasq.conf:
 enable-tftp
 tftp-root=/tmp/tftp
 dhcp-boot=pxelinux.0
lxc.conf: lxc.lxcpath = /srv/lxc

[Launchpad Janitor (janitor)]

Status changed to 'Confirmed' because the bug affects multiple users.

[Serge Hallyn (serge-hallyn)]

Thanks - this is fixed upstream, probably by

commit fb5ab35bfae46f75e988df28da1edce8cbb5f27c
Author: Christian Brauner <email address hidden>
Date: Mon Apr 11 17:13:16 2016 +0200

    lxc-create: fix -B best option

Until that is merged and SRUd, you can get the fix from ppa:ubuntu-lxc/daily.

[Quanah (quanah-zimbra)]

This is breaking the ability to use vagrant with LXC boxes.

/opt/vagrant/embedded/gems/gems/vagrant-1.8.1/lib/vagrant/batch_action.rb:82:in `block (2 levels) in run'
 INFO interface: error: There was an error executing ["sudo", "/usr/bin/env", "lxc-create", "-B", "best", "--template", "/home/quanah/.vagrant.d/gems/gems/vagrant-lxc-1.2.1/scripts/lxc-template", "--name", "u1690_default_1462660055308_76102", "--", "--tarball", "/home/quanah/.vagrant.d/boxes/developerinlondon-VAGRANTSLASH-lxc-xenial/0.1/lxc/rootfs.tar.gz", "--config", "/home/quanah/.vagrant.d/boxes/developerinlondon-VAGRANTSLASH-lxc-xenial/0.1/lxc/lxc-config"]

For more information on the failure, enable detailed logging by setting
the environment variable VAGRANT_LOG to DEBUG.
There was an error executing ["sudo", "/usr/bin/env", "lxc-create", "-B", "best", "--template", "/home/quanah/.vagrant.d/gems/gems/vagrant-lxc-1.2.1/scripts/lxc-template", "--name", "u1690_default_1462660055308_76102", "--", "--tarball", "/home/quanah/.vagrant.d/boxes/developerinlondon-VAGRANTSLASH-lxc-xenial/0.1/lxc/rootfs.tar.gz", "--config", "/home/quanah/.vagrant.d/boxes/developerinlondon-VAGRANTSLASH-lxc-xenial/0.1/lxc/lxc-config"]

For more information on the failure, enable detailed logging by setting
the environment variable VAGRANT_LOG to DEBUG.
 INFO interface: Machine: error-exit ["Vagrant::LXC::Errors::ExecuteError", "There was an error executing [\"sudo\", \"/usr/bin/env\", \"lxc-create\", \"-B\", \"best\", \"--template\", \"/home/quanah/.vagrant.d/gems/gems/vagrant-lxc-1.2.1/scripts/lxc-template\", \"--name\", \"u1690_default_1462660055308_76102\", \"--\", \"--tarball\", \"/home/quanah/.vagrant.d/boxes/developerinlondon-VAGRANTSLASH-lxc-xenial/0.1/lxc/rootfs.tar.gz\", \"--config\", \"/home/quanah/.vagrant.d/boxes/developerinlondon-VAGRANTSLASH-lxc-xenial/0.1/lxc/lxc-config\"]\n\nFor more information on the failure, enable detailed logging by setting\nthe environment variable VAGRANT_LOG to DEBUG."]
quanah@ub16:~/vagrant/u1690$ sudo su -
root@ub16:~# lxc-create -B best --template /home/quanah/.vagrant.d/gems/gems/vagrant-lxc-1.2.1/scripts/lxc-template --name u1690_default_1462660055308_76102 -- --tarball /home/quanah/.vagrant.d/boxes/developerinlondon-VAGRANTSLASH-lxc-xenial/0.1/lxc/rootfs.tar.gz --config /home/quanah/.vagrant.d/boxes/developerinlondon-VAGRANTSLASH-lxc-xenial/0.1/lxc/lxc-config
best is not a valid backing storage type.

[Gennadiy Tarasenko (bitcreator)]

Bringing machine 'default' up with 'lxc' provider...
==> default: Importing base box 'mayflower/trusty64-puppet3'...
There was an error executing ["sudo", "/usr/local/bin/vagrant-lxc-wrapper", "lxc-create", "-B", "best", "--template", "/home/gtarasenko/.vagrant.d/gems/gems/vagrant-lxc-1.2.1/scripts/lxc-template", "--name", "workbench_default_1463040897357_18117", "--", "--tarball", "/home/gtarasenko/.vagrant.d/boxes/mayflower-VAGRANTSLASH-trusty64-puppet3/0.7.3/lxc/rootfs.tar.gz", "--config", "/home/gtarasenko/.vagrant.d/boxes/mayflower-VAGRANTSLASH-trusty64-puppet3/0.7.3/lxc/lxc-config"]

For more information on the failure, enable detailed logging by setting
the environment variable VAGRANT_LOG to DEBUG.
==> default: VM not created. Moving on...

[Ibrahim Awwal (ibrahim-awwal)]

For the vagrant-lxc issue, you can apply the workaround from here:

https://github.com/fgrehm/vagrant-lxc/issues/407

Specifically, define the backingstore manually in your Vagrantfile:

```
config.vm.provider :lxc do |lxc,ovrd|
    ovrd.vm.box = 'fgrehm/trusty64-lxc'
    lxc.backingstore = 'dir'
end
```