With different libvirt version, lxc-enter-namespace return Different Execution results.

"hzguanqiang@xxxxxxxxxxxxxxxx" <hzguanqiang@xxxxxxxxxxxxxxxx> · Thu, 8 Aug 2013 15:56:35 +0800

Hi Alex,
I noticed you did lots of work about lxc-enter-namespace function. There is 
one thing really confusing me and I really want to consult with you about 
it.

When I execute lxc-enter-namespace to get disk space info for lxc container 
under different libvirt version, It return different execution results. Details 
are as following:

Under libvirt of version 1.0.2 with unbuntu host OS:

    # disk space info of Host
    ubuntu@lxc-gq:~$ df 
    -hl                   

    Filesystem      
    Size  Used Avail Use% Mounted on
    /dev/loop7       
    20G   16G  3.2G  84% /
    udev            
    2.0G   12K  2.0G   1% /dev
    tmpfs           
    791M  300K  791M   1% /run
    none            
    5.0M  4.0K  5.0M   1% /run/lock
    none            
    2.0G     0  2.0G   0% /run/shm
    tmpfs           
    2.0G     0  2.0G   0% 
/sys/fs/cgroup
    /dev/nbd5        
    93M  1.6M   87M   2% /home/ubuntu/test

    ubuntu@lxc-gq:~$ vir version
    Compiled against library: libvirt 1.0.2
    Using library: libvirt 1.0.2
    Using API: LXC 1.0.2
    Running hypervisor: LXC 3.8.0

    ubuntu@lxc-gq:~$ vir list
    Id    
    Name                           
    State
    ----------------------------------------------------
    3241  
    instance-0000004b              
    running

    # disk space info of instance
    ubuntu@lxc-gq:~$ vir lxc-enter-namespace 
    3241  /bin/df -hl      
    Filesystem      
    Size  Used Avail Use% Mounted on
    /dev/nbd1       
    1.4G  956M  329M  75% /
    devfs            
    64K  8.0K   56K  13% /dev
    tmpfs            
    64K     0   64K   0% 
    /sys/fs/cgroup
    none            
    396M   12M  384M   3% /run
    none            
    5.0M     0  5.0M   0% /run/lock
    none            
    2.0G     0  2.0G   0% /run/shm

    Then I logged into the lxc container :
    ubuntu@lxc-gq:~$ ssh -i id_rsa_lxc 
    ubuntu@10.0.0.4                        

    Welcome to Ubuntu 12.04.2 LTS (GNU/Linux 
    3.8.0-25-generic x86_64)

    * Documentation:  
    https://help.ubuntu.com/

    System information disabled due to load higher 
    than 2.0

      Get cloud support with Ubuntu Advantage 
    Cloud Guest:

    http://www.ubuntu.com/business/services/cloud

      Use Juju to deploy your cloud instances 
    and workloads:

    https://juju.ubuntu.com/#cloud-precise

    0 packages can be updated.
    0 updates are security updates.

    Last login: Thu Aug  8 07:30:04 2013 from 
    10.0.0.1
    To run a command as administrator (user "root"), 
    use "sudo <command>".
    See "man sudo_root" for details.

    ubuntu@lxc3:~$ df -hl
    Filesystem      
    Size  Used Avail Use% Mounted on
    /dev/nbd1       
    1.4G  956M  328M  75% /
    devfs            
    64K  8.0K   56K  13% /dev
    tmpfs            
    64K     0   64K   0% 
    /sys/fs/cgroup
    none            
    396M   12M  384M   3% /run
    none            
    5.0M     0  5.0M   0% /run/lock
    none            
    2.0G     0  2.0G   0% 
  /run/shm
From above,  We can see under libvirt version 1.0.2, through 
lxc-enter-namespace, disk space info can be obtained and it's the same as info 
got from lxc inside.

But when I did the same thing under libvirt of version 1.1.0 with debian 
host OS, the execution result changed:

    #disk info of host
    hzguanqiang@debian:~$ df -hl
    Filesystem                                              
    Size  Used Avail Use% Mounted on
    rootfs                                                  
    4.0G  1.6G  2.2G  42% /
    udev                                                     
    10M     0   10M   0% /dev
    tmpfs                                                   
    4.8G  468K  4.8G   1% /run
    /dev/disk/by-uuid/12bb656b-4f80-4386-aa07-4bf90a3111b4  
    4.0G  1.6G  2.2G  42% /
    tmpfs                                                   
    5.0M  4.0K  5.0M   1% /run/lock
    tmpfs                                                   
    9.9G     0  9.9G   0% /run/shm
    /dev/sda8                                               
    428G  112G  313G  27% /home
    /dev/sda6                                               
    7.9G  159M  7.8G   2% /tmp
    /dev/sda5                                                
    16G  2.7G   14G  17% /var
    cgroup_root                                              
    24G     0   24G   0% 
    /sys/fs/cgroup
    /dev/nbd5                                               
    1.4G  851M  466M  65% 
    /home/openstack/stack/data/nova/instances/eed45ccb-3707-4815-9ae4-c7a2f56adb64/rootfs

    hzguanqiang@debian:~$ vir version
    Compiled against library: libvirt 1.1.0
    Using library: libvirt 1.1.0
    Using API: LXC 1.1.0
    Running hypervisor: LXC 3.2.46

    hzguanqiang@debian:~$ vir list
    Id    
    Name                           
    State
    ----------------------------------------------------
    6096  
    instance-00000037              
    running
    27981 
    instance-00000038              
    running
    30846 
    instance-0000001a              
    running

    hzguanqiang@debian:~$ vir 
    lxc-enter-namespace  instance-00000037 /bin/df -hl
    libvirt:  error : argument unsupported: 
    Security model  cannot be entered

    hzguanqiang@debian:~$ vir 
    lxc-enter-namespace  instance-00000037 --noseclabel /bin/df -hl
    Filesystem                                              
    Size  Used Avail Use% Mounted on
    rootfs                                                  
    4.0G  1.6G  2.2G  42% /
    udev                                                     
    10M     0   10M   0% /dev
    tmpfs                                                   
    4.8G  468K  4.8G   1% /run
    /dev/disk/by-uuid/12bb656b-4f80-4386-aa07-4bf90a3111b4  
    4.0G  1.6G  2.2G  42% /
    tmpfs                                                   
    5.0M  4.0K  5.0M   1% /run/lock
    tmpfs                                                   
    9.9G     0  9.9G   0% /run/shm
    /dev/sda8                                               
    428G  112G  313G  27% /home
    /dev/sda6                                               
    7.9G  159M  7.8G   2% /tmp
    /dev/sda5                                                
    16G  2.7G   14G  17% /var
    cgroup_root                                              
    24G     0   24G   0% 
    /sys/fs/cgroup
    /dev/nbd5                                               
    1.4G  851M  466M  65% 
    /home/openstack/stack/data/nova/instances/eed45ccb-3707-4815-9ae4-c7a2f56adb64/rootfs

    Then I logged into the lxc container :
    hzguanqiang@debian:~$ ssh -i id_rsa 
    ubuntu@10.160.70.2
      Welcome to Ubuntu 12.04.2 LTS (GNU/Linux 
    3.2.46-openstack-amd64 x86_64)

    * Documentation:  
    https://help.ubuntu.com/

      System information as of Wed Aug  7 
    10:49:35 UTC 2013

      System load:  
    0.62               
    Processes:           
    31
      Usage of /:   20.9% of 
    19.69GB   Users logged in:     1
      Memory usage: 
    51%                
    IP address for eth0: 10.160.70.2
      Swap usage:   0%

      Graph this data and manage this system at 
    https://landscape.canonical.com/

      Get cloud support with Ubuntu Advantage 
    Cloud Guest:

    http://www.ubuntu.com/business/services/cloud

      Use Juju to deploy your cloud instances 
    and workloads:

    https://juju.ubuntu.com/#cloud-precise

    Last login: Wed Aug  7 10:49:35 2013 from 
    10.160.70.3
    ubuntu@lxc1:~$ df -hl
    Filesystem      
    Size  Used Avail Use% Mounted on
    /dev/loop2       
    20G   11G  8.3G  57% /
    devfs            
    64K  8.0K   56K  13% /dev
    tmpfs            
    64K     0   64K   0% 
    /sys/fs/cgroup
    none            
    4.8G  6.4M  4.8G   1% /run
    none            
    5.0M     0  5.0M   0% /run/lock
    none             
    24G     0   24G   0% 
  /run/shm

From above, We can see under libvirt version 1.1.0,  disk space info 
of lxc container gotten through lxc-enter-namespace are different from info got 
from lxc inside, but the same as host.

Why does this happen? Is there a bug or anything?

Thanks
--------------------------------------------------------------------------------

------------------     
Best regards!
GuanQiang
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