On Fri, Nov 9, 2012 at 10:52 PM, Serge Hallyn <serge.hallyn@canonical.com>wrote:
On Fri, Nov 9, 2012 at 12:09 AM, unicell <unicell@gmail.com> wrote:
Hi,
I'm trying to manage LXC instances through OpenStack, which use
a virtualization driver layer. After launching LXC instance, I simply could not attach to the console.
virsh # list Id Name State ---------------------------------- 14366 instance-00000078 running
virsh # console 14366 Connected to domain instance-00000078 Escape character is ^]
And it keeps stuck here.
Initially I thought it could be a cgroup device config issue, and
Quoting unicell (unicell@gmail.com): libvirt as tried to
"echo ‘c 5:1 rwm'
/cgroup/devices/libvirt/lxc/instance-00000078/devices.allow“, to add /dev/console access right to the container. But it does not work, console stilll not working.
Before the cgroup tweaking, devices.list are as follows
[root@localhost libvirt]# cat /cgroup/devices/libvirt/lxc/instance-0000007a/devices.list
c 1:3 rwm c 1:5 rwm c 1:7 rwm c 1:8 rwm c 1:9 rwm c 5:0 rwm c 5:2 rwm c 136:* rwm
I'm not quite sure what kind of issue could possibly cause this console access issue. Cause I'm now using two different guest OS templates on two
Just a few things to help you look around:
Both lxc and libvirt-lxc provide consoles by creating a pty on the host and bind-mounting that onto /dev/ttyN in the guest before starting init.
Ubuntu on the host passes 'container=lxc' (or 'container=libvirt') to the container, which tells ubuntu in the container to not do some things (look for 'container' in /etc/init/*; also things like mountall accept that they should not do some things in containers).
You can investigate /dev/ttyN and /dev/console in your container by looking at the pid of init in the container, and looking at /proc/$pid/root/dev/{console,tty*}
That *should* show 136:* devices, but I assume that in the cases where it is not working it will show 4:* for ttyN. If you look at cat /proc/$pid/root/proc/1/mounts I expect you'll see a /dev is mounted in the container. Which hides the bind mounts which (libvirt-)lxc has set up.
-serge
Serge, you're right. In console not working environment, /dev is mounted inside container. As you pointed out, it hides what (libvirt-)lxc has set up and messed up with the conosle devices. Thank you so much for providing this clue, and I'll dig into upstart scripts to look at more. I doubt there're some difference in container set up logic in 'container=lxc' and 'container=lxc-libvirt' situation, which caused the /dev/ mounting issue. More information for your reference. As you can see, launching by lxc and launching by libvirt-lxc makes a big difference here. -- console working case (started by lxc-start) -- root@localhost:/var/lib/lxc/CN/rootfs/etc/init# cat /proc/10018/root/proc/1/mounts rootfs / rootfs rw 0 0 /dev/mapper/lxcvg-lxcimages / ext3 rw,relatime,errors=remount-ro,user_xattr,acl,barrier=1,data=ordered 0 0 proc /proc proc rw,nosuid,nodev,noexec,relatime 0 0 sysfs /sys sysfs rw,relatime 0 0 devpts /dev/lxc/console devpts rw,nosuid,noexec,relatime,gid=5,mode=620,ptmxmode=000 0 0 devpts /dev/lxc/tty1 devpts rw,nosuid,noexec,relatime,gid=5,mode=620,ptmxmode=000 0 0 devpts /dev/lxc/tty2 devpts rw,nosuid,noexec,relatime,gid=5,mode=620,ptmxmode=000 0 0 devpts /dev/lxc/tty3 devpts rw,nosuid,noexec,relatime,gid=5,mode=620,ptmxmode=000 0 0 devpts /dev/lxc/tty4 devpts rw,nosuid,noexec,relatime,gid=5,mode=620,ptmxmode=000 0 0 devpts /dev/pts devpts rw,relatime,mode=600,ptmxmode=666 0 0 devpts /dev/ptmx devpts rw,relatime,mode=600,ptmxmode=666 0 0 none /proc/sys/fs/binfmt_misc binfmt_misc rw,nosuid,nodev,noexec,relatime 0 0 none /sys/fs/fuse/connections fusectl rw,relatime 0 0 none /sys/kernel/debug debugfs rw,relatime 0 0 none /sys/kernel/security securityfs rw,relatime 0 0 none /run tmpfs rw,nosuid,noexec,relatime,size=378636k,mode=755 0 0 none /run/lock tmpfs rw,nosuid,nodev,noexec,relatime,size=5120k 0 0 none /run/shm tmpfs rw,nosuid,nodev,relatime 0 0 root@localhost:/var/lib/lxc/CN/rootfs/etc/init# ls -l /proc/10018/root/dev/{console,tty*} lrwxrwxrwx 1 root root 11 Nov 9 23:55 /proc/10018/root/dev/console -> lxc/console crw-rw-rw- 1 root tty 5, 0 Oct 23 20:40 /proc/10018/root/dev/tty crw------- 1 root tty 4, 0 Oct 23 20:01 /proc/10018/root/dev/tty0 lrwxrwxrwx 1 root root 8 Nov 9 23:55 /proc/10018/root/dev/tty1 -> lxc/tty1 lrwxrwxrwx 1 root root 8 Nov 9 23:55 /proc/10018/root/dev/tty2 -> lxc/tty2 lrwxrwxrwx 1 root root 8 Nov 9 23:55 /proc/10018/root/dev/tty3 -> lxc/tty3 lrwxrwxrwx 1 root root 8 Nov 9 23:55 /proc/10018/root/dev/tty4 -> lxc/tty4 crw------- 1 root tty 4, 5 Oct 23 20:01 /proc/10018/root/dev/tty5 crw------- 1 root tty 4, 6 Oct 23 20:01 /proc/10018/root/dev/tty6 crw------- 1 root tty 4, 7 Oct 23 20:01 /proc/10018/root/dev/tty7 crw------- 1 root tty 4, 8 Oct 23 20:01 /proc/10018/root/dev/tty8 crw------- 1 root tty 4, 9 Oct 23 20:01 /proc/10018/root/dev/tty9 console *NOT* working case (started by libvirt) -- [root@localhost instances]# cat /proc/2086/root/proc/1/mounts rootfs / rootfs rw 0 0 devpts /dev/pts devpts rw,relatime,gid=5,mode=620,ptmxmode=666 0 0 /dev/nbd14 / ext3 rw,relatime,errors=continue,user_xattr,acl,barrier=1,data=ordered 0 0 devpts /dev/pts devpts rw,relatime,gid=5,mode=620,ptmxmode=666 0 0 devfs /dev tmpfs rw,nosuid,relatime,mode=755 0 0 <-- * /dev is mounted here * 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 /dev/sda2 /selinux ext4 ro,relatime,barrier=1,data=ordered 0 0 devpts /dev/ptmx devpts rw,relatime,gid=5,mode=620,ptmxmode=666 0 0 [root@localhost instances]# ls -l /proc/2086/root/dev/{console,tty*} lrwxrwxrwx 1 root root 10 Nov 9 23:53 /proc/2086/root/dev/console -> /dev/pts/0 lrwxrwxrwx 1 root root 10 Nov 9 23:53 /proc/2086/root/dev/tty1 -> /dev/pts/0 -- Qiu Yu