[libvirt-users] libvirt_lxc and sysfs [SOLVED]
pr.G
gg at sbmg.ru
Mon Jun 10 06:49:58 UTC 2013
On Mon, Jun 10, 2013 at 01:58:29PM +0800, Gao feng wrote:
> On 06/10/2013 01:41 PM, pr.G wrote:
> > On Mon, Jun 10, 2013 at 09:29:32AM +0400, свящ. Георгий Гольцов wrote:
> >> On Mon, Jun 10, 2013 at 09:07:08AM +0800, Gao feng wrote:
> >>> On 06/09/2013 08:14 PM, pr.G wrote:
> >>>> Hello.
> >>>>
> >>>> Is it possible to start container via libvirt_lxc without mounting /sys
> >>>> inside container?
> >>>>
> >>>> When I start container via lxc-start and do not add mount point to config,
> >>>> then /sys inside container is empty.
> >>>>
> >>>> When I do it via virsh -c lxc:// container.xml, then
> >>>> /sys contains sysfs of the host and /sys on host becomes remounting read-only.
> >>>
> >>> how can it be true? Can you post your /proc/mounts on host and container?
> >>>
> >>>>
> >>>> Am I doing something wrong or is this feature of libvirt_lxc?
> >>>>
> >>>
> >>> Absolutely it's not a feature.
> >>>
> >>> Thanks!
> >>>
> > Thanks for the quick reply.
> > I was surprised too. I didn't post /proc/mounts to container.
>
> I mean show the /proc/mounts of container and host
>
> in container:
> cat /proc/mounts
>
> [root at Donkey /]# cat /proc/mounts
> rootfs / rootfs rw 0 0
> devpts /dev/pts devpts rw,nosuid,relatime,gid=5,mode=620,ptmxmode=666 0 0
> devfs /dev tmpfs rw,nosuid,relatime,size=64k,mode=755 0 0
> /dev/sdb2 / ext4 rw,relatime,data=ordered 0 0
> proc /proc proc rw,nosuid,nodev,noexec,relatime 0 0
> proc /proc/sys proc ro,relatime 0 0
> sysfs /sys sysfs ro,relatime 0 0
> libvirt /proc/meminfo fuse rw,nosuid,nodev,relatime,user_id=0,group_id=0,allow_other 0 0
> tmpfs /sys/fs/cgroup tmpfs rw,nosuid,nodev,noexec,relatime,size=64k,mode=755,uid=1000,gid=1000 0 0
> cgroup /sys/fs/cgroup/cpu,cpuacct cgroup rw,nosuid,nodev,noexec,relatime,cpuacct,cpu 0 0
> cgroup /sys/fs/cgroup/cpuset cgroup rw,nosuid,nodev,noexec,relatime,cpuset 0 0
> cgroup /sys/fs/cgroup/memory cgroup rw,nosuid,nodev,noexec,relatime,memory 0 0
> cgroup /sys/fs/cgroup/devices cgroup rw,nosuid,nodev,noexec,relatime,devices 0 0
> cgroup /sys/fs/cgroup/freezer cgroup rw,nosuid,nodev,noexec,relatime,freezer 0 0
> cgroup /sys/fs/cgroup/blkio cgroup rw,nosuid,nodev,noexec,relatime,blkio 0 0
> cgroup /sys/fs/cgroup/net_cls cgroup rw,nosuid,nodev,noexec,relatime,net_cls 0 0
> cgroup /sys/fs/cgroup/perf_event cgroup rw,nosuid,nodev,noexec,relatime,perf_event 0 0
> devpts /dev/ptmx devpts rw,nosuid,relatime,gid=5,mode=620,ptmxmode=666 0 0
>
in container:
root at container:~# cat /proc/mounts
rootfs / rootfs rw 0 0
devpts /dev/pts devpts rw,seclabel,nosuid,noexec,relatime,gid=5,mode=620,ptmxmode=666 0 0
/dev/mapper/vg0-var / ext4 rw,seclabel,relatime,user_xattr,barrier=1,data=ordered 0 0
devpts /dev/pts devpts rw,seclabel,nosuid,relatime,gid=5,mode=620,ptmxmode=666 0 0
proc /proc proc rw,nosuid,nodev,noexec,relatime 0 0
proc /proc/sys proc ro,relatime 0 0
sysfs /sys sysfs ro,seclabel,relatime 0 0
devfs /dev tmpfs rw,seclabel,nosuid,relatime,size=64k,mode=755 0 0
devpts /dev/ptmx devpts rw,seclabel,nosuid,relatime,gid=5,mode=620,ptmxmode=666 0 0
selinuxfs /sys/fs/selinux selinuxfs rw,relatime 0 0
tmpfs /run tmpfs rw,rootcontext=system_u:object_r:var_t:s0,seclabel,nosuid,noexec,relatime,size=6609200k,mode=755
0 0
tmpfs /run/lock tmpfs rw,rootcontext=system_u:object_r:var_t:s0,seclabel,nosuid,nodev,noexec,relatime,size=5120k
0 0
tmpfs /run/shm tmpfs rw,rootcontext=system_u:object_r:var_t:s0,seclabel,nosuid,nodev,noexec,relatime,size=32748940k
0 0
>
> and in host
> [root at Donkey libvirt]# cat /proc/mounts
> rootfs / rootfs rw 0 0
> proc /proc proc rw,nosuid,nodev,noexec,relatime 0 0
> sysfs /sys sysfs rw,nosuid,nodev,noexec,relatime 0 0
> devtmpfs /dev devtmpfs rw,nosuid,size=5081344k,nr_inodes=1270336,mode=755 0 0
> securityfs /sys/kernel/security securityfs rw,nosuid,nodev,noexec,relatime 0 0
> tmpfs /dev/shm tmpfs rw,nosuid,nodev 0 0
> devpts /dev/pts devpts rw,nosuid,noexec,relatime,gid=5,mode=620,ptmxmode=000 0 0
> tmpfs /run tmpfs rw,nosuid,nodev,mode=755 0 0
> tmpfs /sys/fs/cgroup tmpfs rw,nosuid,nodev,noexec,mode=755 0 0
> cgroup /sys/fs/cgroup/systemd cgroup rw,nosuid,nodev,noexec,relatime,release_agent=/usr/lib/systemd/systemd-cgroups-agent,name=systemd 0 0
> pstore /sys/fs/pstore pstore rw,nosuid,nodev,noexec,relatime 0 0
> cgroup /sys/fs/cgroup/cpuset cgroup rw,nosuid,nodev,noexec,relatime,cpuset 0 0
> cgroup /sys/fs/cgroup/cpu,cpuacct cgroup rw,nosuid,nodev,noexec,relatime,cpuacct,cpu 0 0
> cgroup /sys/fs/cgroup/memory cgroup rw,nosuid,nodev,noexec,relatime,memory 0 0
> cgroup /sys/fs/cgroup/devices cgroup rw,nosuid,nodev,noexec,relatime,devices 0 0
> cgroup /sys/fs/cgroup/freezer cgroup rw,nosuid,nodev,noexec,relatime,freezer 0 0
> cgroup /sys/fs/cgroup/net_cls cgroup rw,nosuid,nodev,noexec,relatime,net_cls 0 0
> cgroup /sys/fs/cgroup/blkio cgroup rw,nosuid,nodev,noexec,relatime,blkio 0 0
> cgroup /sys/fs/cgroup/perf_event cgroup rw,nosuid,nodev,noexec,relatime,perf_event 0 0
> cgroup /sys/fs/cgroup/hugetlb cgroup rw,nosuid,nodev,noexec,relatime,hugetlb 0 0
> ....
in host
root at host:~# cat /proc/mounts
rootfs / rootfs rw 0 0
sysfs /sys sysfs rw,seclabel,nosuid,nodev,noexec,relatime 0 0
proc /proc proc rw,nosuid,nodev,noexec,relatime 0 0
udev /dev devtmpfs rw,seclabel,relatime,size=10240k,nr_inodes=8251651,mode=755 0 0
devpts /dev/pts devpts rw,seclabel,nosuid,noexec,relatime,gid=5,mode=620,ptmxmode=000 0 0
tmpfs /run tmpfs rw,seclabel,nosuid,noexec,relatime,size=6609200k,mode=755 0 0
/dev/disk/by-uuid/14601dd5-89c4-46c9-aa88-dbfbfb1f092a / ext4 rw,seclabel,noatime,errors=remount-ro,user_xattr,barrier=1,data=ordered
0 0
selinuxfs /sys/fs/selinux selinuxfs rw,relatime 0 0
tmpfs /run/lock tmpfs rw,rootcontext=system_u:object_r:var_lock_t:s0,seclabel,nosuid,nodev,noexec,relatime,size=5120k
0 0
tmpfs /run/shm tmpfs rw,rootcontext=system_u:object_r:tmpfs_t:s0,seclabel,nosuid,nodev,noexec,relatime,size=13218380k
0 0
...
/dev/mapper/vg0-var /var ext4 rw,seclabel,noatime,user_xattr,barrier=1,data=ordered 0 0
cgroup /sys/fs/cgroup cgroup rw,relatime,perf_event,blkio,net_cls,freezer,devices,memory,cpuacct,cpu,cpuset,clone_children
0 0
rpc_pipefs /var/lib/nfs/rpc_pipefs rpc_pipefs rw,relatime 0 0
>
>
> > libvirt_lxc did it for me.
> > I read http://libvirt.org/drvlxc.html about Filesystem mounts:
> > "
> > In the absence of any explicit configuration, the container will
> > inherit the host OS filesystem mounts. A number of mount points will be
> > made read only, or re-mounted with new instances to provide container
> > specific data. The following special mounts are setup by libvirt
> >
> > * /dev a new "tmpfs" pre-populated with authorized device nodes
> > * /dev/pts a new private "devpts" instance for console devices
> > * /sys the host "sysfs" instance remounted read-only
> > * /proc a new instance of the "proc" filesystem
> > * /proc/sys the host "/proc/sys" bind-mounted read-only
> > * /sys/fs/selinux the host "selinux" instance remounted read-only
> > * /sys/fs/cgroup/NNNN the host cgroups controllers bind-mounted to
> > * only expose the sub-tree associated with the container
> > * /proc/meminfo a FUSE backed file reflecting memory limits of the
> > * container
> > "
> > Can I disable this behavior?
> > How do I specify an explicit configuration?
>
> This can't be disabled and it's no need to disable this.
>
> >
> > my container.xml: (The entire xml file is shown in the my original post)
> >> ...
> >> <devices>
> >> <emulator>/usr/lib/libvirt/libvirt_lxc</emulator>
> >> <filesystem type='mount'>
> >> <source dir='/var/lxc/ns1/rootfs'/>
> >> <target dir='/'/>
> >> </filesystem>
> >> ...
> >> </device>
> >> ...
> >>
>
> Your configuration looks good, In container,the sysfs is mounted as read-only default.
> Since we don't want user in container to change some sysfs-configuration of host.
My problem was after first start lxc containet by virsh (after reboot host), the host /sys fs
becomes ro.
After I remount it rw manually and start container again, all OK:
/sys in host - rw, in container - ro.
Thanks, Gao.
This problem was solved for me.
>
> Thanks
> Gao.
> >>
> >>>> Thanks.
> >>>>
> >>>> root at host:~# uname -a
> >>>> Linux host 3.2.0-4-amd64 #1 SMP Debian 3.2.41-2+deb7u2 x86_64 GNU/Linux
> >>>>
> >>>> root at host:~# cat /etc/os-release
> >>>> PRETTY_NAME="Debian GNU/Linux 7.0 (wheezy)"
> >>>> ...
> >>>>
> >>>> root at host:~# dpkg -l | grep libvirt
> >>>> ii libvirt-bin 0.9.12-11 amd64 programs for the libvirt library
> >>>> ii libvirt0 0.9.12-11 amd64 library for interfacing with different virtualization systems
> >>>>
> >>>>
> >>>> container.xml:
> >>>> <domain type='lxc'>
> >>>> <name>ns1</name>
> >>>> <memory>524288</memory>
> >>>> <os>
> >>>> <type>exe</type>
> >>>> <init>/sbin/init</init>
> >>>> </os>
> >>>> <vcpu>1</vcpu>
> >>>> <clock offset='utc'/>
> >>>> <on_poweroff>destroy</on_poweroff>
> >>>> <on_reboot>restart</on_reboot>
> >>>> <on_crash>destroy</on_crash>
> >>>> <devices>
> >>>> <emulator>/usr/lib/libvirt/libvirt_lxc</emulator>
> >>>> <filesystem type='mount'>
> >>>> <source dir='/var/lxc/ns1/rootfs'/>
> >>>> <target dir='/'/>
> >>>> </filesystem>
> >>>> <interface type='bridge'>
> >>>> <source bridge='br0'/>
> >>>> <mac address='52:54:00:de:74:06'/>
> >>>> </interface>
> >>>> <console type='pty' />
> >>>> </devices>
> >>>> </domain>
> >>>>
> >>>>
> >>>> _______________________________________________
> >>>> libvirt-users mailing list
> >>>> libvirt-users at redhat.com
> >>>> https://www.redhat.com/mailman/listinfo/libvirt-users
> >>>>
> >>>
> >
>
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