Vzctl for upstream kernel

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Revision as of 16:16, 19 September 2012 by Kir (talk | contribs) (Networking: howto)
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Since version 4.0, vzctl tool can be used with upstream (non-OpenVZ) Linux kernels (that essentially means any recent 3.x kernel). At the moment, it provides just basic functionality. It is currently possible to create and start a container with the same steps as one would use for a normal OpenVZ container. Other features may be present with limited functionality, while some are not present at all.

Warning.svg Warning: Running vzctl on upstream kernels is considered an experimental feature. See #Limitatons below.

Installation

Yellowpin.svg Note: This section describes installation for RPM-based distros. See #Building below if you want to compile vzctl from source.

First, set up OpenVZ yum repository. Download openvz.repo file and put it to your /etc/yum.repos.d/ repository, and import OpenVZ GPG key used for signing RPM packages. This can be achieved by the following commands, as root:

wget -P /etc/yum.repos.d/ http://download.openvz.org/openvz.repo
rpm --import http://download.openvz.org/RPM-GPG-Key-OpenVZ

In case you can not cd to /etc/yum.repos.d, it means either yum is not installed on your system, or yum version is too old.

Then, install vzctl-core package:

yum install vzctl-core

Usage

For supported features, usage is expected to be the same as standard vzctl tool. See vzctl(8) for more information.

Networking

Template:Warn

Networking is available through the switches --netdev_add, --netif_add, and their respective deletion counterparts. Unfortunately now it requires some manual configuration.

Bridged networking

The following example assumes

  • you already have a bridge configured on the host system
  • bridge interface name is virbr0
  • CT is running Red Hat like distro (CentOS)
vzctl set $CTID --netif_add eth0,,,,virbr0 --save
echo "NETWORKING=yes" > /vz/private/$CTID/etc/sysconfig/network
cat << EOF > /vz/private/$CTID/etc/sysconfig/network-scripts/ifcfg-eth0
DEVICE=eth0
BOOTPROTO=dhcp
ONBOOT=yes
EOF
vzctl start $CTID

After this, you can find CT IP using this:

# ip netns exec $CTID ip address list

Limitations

The following vzctl commands are not working at all:

  • quotaon/quotaoff/quotainit (vzquota-specific)
  • convert, compact, snapshot* (ploop-specific)
  • console (needs a virtual /dev/console, /dev/ttyN device)
  • enter, exec and runscript (need pidns entering support)
  • chkpnt, restore (currently need OpenVZ-kernel-specific checkpointing, CRIU will be supported later)

The following commands have severe limitations:

  • stop. A container can be stopped from inside (say if one is connected to CT over ssh) in case the underlying kernel supports rebooting a PID namespace (> 3.4). Using vzctl, the "stop" command is not supported, unless accompanied by the --fast switch, which will simply forceably kill all processes in the container.

The following binaries are not ported to work on top of upstream kernel:

  • vzlist
  • vzcalc
  • vzcfgvalidate
  • vzcpucheck
  • vzmemcheck
  • vzmigrate
  • vzeventd
  • vzpid
  • vzsplit
  • vzubc

/proc and /sys

Software that depend on information supplied by the proc filesystem may not work correctly, since there is not a full solution for full /proc virtualization. For instance, /proc/stat is not yet virtualized, and top will show distorted values.

Resource management

Setting resources like --ram and --cpuunits work, but there their effect is dependent on what the current kernel supports, through the cgroups subsystem. When a particular cgroup file is present, it will be used. Currently, vzctl will search for the following files:

  • cpu.cfs_quota_us
  • cpu.shares
  • cpuset.cpus
  • memory.limit_in_bytes
  • memory.memsw.limit_in_bytes
  • memory.kmem.limit_in_bytes
  • memory.kmem.tcp.limit_in_bytes


Building

Dependencies

The following software needs to be installed on your system:

  • iproute2 >= 3.0.0 (runtime only)
  • libcgroup >= 0.38

Download

You can get the latest released version from Download/vzctl/4.11.1#sources or directly from download:utils/vzctl/current/src/.

If you are living on the bleeding edge, get vzctl sources from git. Then run autogen.sh to recreate auto* files:

git clone git://git.openvz.org/pub/vzctl
cd vzctl
./autogen.sh

Compile

Usual ./confi

t makes sense to add --without-ploop (unless you want ploop compiled it) because otherwise you will need ploop lib headers.

$ ./configure --with-cgroup --without-ploop