ADMIN

OpenVZ
Virtualization
a number of community templates
(Figure 4).
Configuring the Host
Environment
The /etc/vz/vz.conf file lets you
configure the host environment. This
is where you specify the path to the
container and template data on the
host filesystem. If you prefer not to
use the defaults of
subnet and tell them the DNS server
address, which lets OpenVZ create
venet devices. All of the following
commands must be given in the host
context. To do this, you first need to
stop the VE and then set all the basic
parameters. For example, you can set
the hostname for the VE as follows:
sudo vzctl set VEID U
‐‐hostname Hostname ‐‐save
The ‐‐ipadd option lets you assign a
local IP address. If you need to install
a large number of VEs, use VEID as
the host part of the numeric address.
sudo vzctl set VEID ‐‐ipadd U
IP-Address ‐‐save
The DNS server can be configured using
the ‐‐nameserver option:
sudo vzctl set VEID U
‐‐nameserver Nameserver-address ‐‐save E
TEMPLATE=/var/lib/vz/template
VE_ROOT=/var/lib/vz/root/$VEID
VE_PRIVATE=/var/lib/vz/private/$VEID
you can set your own paths. VE_ROOT
is the mountpoint for the root directory
of the container. The private
data for the container are mounted in
VE_PRIVATE. VEID is a unique ID that
identifies an instance of the virtual
environment. All OpenVZ tools use
this container ID to address the required
container.
Figure 6: The virtual environment uses venet devices to communicate with the outside world.
Creating Containers
The vzctl, which is only available
in the host context, creates containers
and handles most management
tasks, too. In the following example,
I used it to create a new VE based on
a template for openSUSE 11.1 that I
downloaded:
Figure 7: The vzlist command outputs a list of active VEs.
sudo vzctl create VEID U
‐‐ostemplate suse‐11.1‐x86_64
The template name is specified without
the path and file extension. The
sudo vzctl start VEID starts the
VE, and sudo vzctl stop VEID stops
it again (Figure 5). The commands
sudo vzctl enter VEID and exit let
you enter and exit the VE.
Entering the VE gives you a working
root shell without prompting you for
a password. Unfortunately, you can’t
deny root access in the host context.
Network Configuration
The next step is to configure network
access for the container. OpenVZ
supports various network modes for
this. The easiest option is to assign
the VEs an IP on the local network/​
Figure 8: User Bean Counters, a set of configuration parameters, allow the administrator to limit resources
for each virtual environment.
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