Vnx-examples
VNX Simple Scenarios
Contents
Description
Several simple example scenarios are included in VNX distribution to allow testing the tool functionalities with the different types of virtual machines supported (see /usr/share/vnx/examples/simple_*.xml files).
Each simple scenario includes just one virtual machine connected to a virtual network (Net0, 10.0.0.0/24), where the hosts has also a virtual network interface connected (10.0.0.1).
The simple scenarios are prepared to be started and tested individually or to be started all together to form the compound scenario shown in Figure 1.
The following simple scenarios are available:
| Scenario file name | Description | VM ip address |
| simple_uml.xml | Just one User Mode Linux (UML) Debian system | 10.0.0.2 |
| simple_winxp.xml | Just one KVM Windows XP system | 10.0.0.3 |
| simple_ubuntu.xml | Just one KVM Ubuntu system without GUI | 10.0.0.4 |
| simple_ubuntu-gui.xml | Just one KVM Ubuntu system with minimal GNOME GUI | 10.0.0.5 |
| simple_freebsd.xml | Just one KVM FreeBSD system without GUI | 10.0.0.6 |
| simple_freebsd-gui.xml | Just one KVM FreeBSD system with minimal GNOME GUI | 10.0.0.7 |
| simple_win7.xml | Just one KVM Windows 7 system | 10.0.0.8 |
| simple_fedora.xml | Just one KVM Fedora system without GUI | 10.0.0.9 |
| simple_fedora-gui.xml | Just one KVM Fedora system with a GNOME GUI | 10.0.0.10 |
| simple_dynamips.xml | Just one Dynamips emulated CISCO 3600 router | 10.0.0.11 |
| simple_dynamips2.xml | Just one Dynamips emulated CISCO 7200 router | 10.0.0.12 |
| simple_olive.xml | Just one Olive emulated Juniper router | 10.0.0.13 |
| simple_centos.xml | Just one KVM CentOS system without GUI | 10.0.0.15 |
| simple_centos-gui.xml | Just one KVM CentOS system with a GNOME GUI | 10.0.0.16 |
All scenarios are available in /usr/share/vnx/examples directory. See, for example, the content of simple_ubuntu-gui.xml scenario at the end of this page
Starting a simple scenario
You can start VNX scenarios either from a local shell window or remotely using an SSH session with X-forwarding enabled. For example, if you connect to the VNX host from a Unix or MacOS system you can use:
ssh -X <vnx-host-address-or-name>
If you connect from another system, just investigate how to configure your SSH client to do X-forwarding (most of them include it).
In case of remote connections, it is recommended to test that X-forwarding is working by launching a "xterm" or "xeyes" application and checking that the application window is correctly launched. Beware that X-forwarding is very bandwidth consuming, so you will need a good connectivity between your system and the host were VNX runs.
As VNX needs root priviledges, you have to be root in the shell window or, alternatively, if your account is allowed to "sudo" root (as typically is, for example, in Ubuntu systems), just precede vnx commands with "sudo", as shown below.
To start, for example, the simple_ubuntu-gui scenario:
cd /usr/share/vnx/examples/ sudo vnx -f simple_ubuntu-gui.xml -v --create
You will see the two virtual machine consoles opening: the graphical one showing the gnome desktop and the text console.
Beware that, once the virtual machine has completely started, the VNX autoconfiguration daemon (VNXACED) has to do its job configuring the name and the network interfaces parameters and restarting the machine for the changes to take effect. After that restart, the virtual machine is ready to be used.
Once started, you can test the network connectivity from the host to the virtual machine:
# ping -c 4 10.0.0.5 PING 10.0.0.5 (10.0.0.5) 56(84) bytes of data. 64 bytes from 10.0.0.5: icmp_seq=1 ttl=64 time=0.197 ms 64 bytes from 10.0.0.5: icmp_seq=2 ttl=64 time=0.188 ms 64 bytes from 10.0.0.5: icmp_seq=3 ttl=64 time=0.177 ms 64 bytes from 10.0.0.5: icmp_seq=4 ttl=64 time=0.171 ms --- 10.0.0.5 ping statistics --- 4 packets transmitted, 4 received, 0% packet loss, time 3001ms rtt min/avg/max/mdev = 0.171/0.183/0.197/0.013 ms
If you close the consoles, you can reopen them with the following commands:
sudo vnx -f simple_ubuntu-gui.xml -v --console --cid con0 -M ubuntu-gui sudo vnx -f simple_ubuntu-gui.xml -v --console --cid con1 -M ubuntu-gui
Or much simpler, you can use libvirt commands:
# sudo virsh list Id Nombre Estado ---------------------------------- 31 ubuntu-gui running # virt-viewer 31 & # To open the graphical console # xterm -e "sudo virsh console 31" & # To open the text console
Beware that only one textual console can be used at a time. If you open a second one, you will experiment a strange behaviour as both consoles will compete for the pts terminal. On the contrary, you can open several graphical console simultaneously.
See VNX Console Management for more details.
Executing commands
You can also execute commands on the virtual machine from the host by means of the <exec> tags in the XML scenario specification:
For example, you can start the calculator or the xeyes application on the virtual machine by issuing:
sudo vnx -f simple_ubuntu-gui.xml -v --exe calc sudo vnx -f simple_ubuntu-gui.xml -v --exe xeyes
Those commands execute what is defined in the <exec> tags with seq="calc" or seq="xeyes" respectively:
<!-- Start xeyes application --> <exec seq="xeyes" type="verbatim" ostype="xexec">xeyes</exec> <!-- Start calculator --> <exec seq="calc" type="verbatim" ostype="xexec">gcalctool</exec> <exec seq="calcoff" type="verbatim" ostype="system">pkill gcalctool</exec>
The "ostype" attribute is used to specify the type of command included in <exec> tag, either command line (CLI) or graphical (GUI), and whether vnx tool waits for command execution end or not. For values are posible:
| ostype | Type of commands | Waits for command execution end |
| system | CLI | YES |
| exec | CLI | NO |
| xsystem | GUI | YES |
| xexec | GUI | NO |
You can check, for example, the "xexec" value with:
sudo vnx -f simple_ubuntu-gui.xml -v --exe xeyes2
which executes the command:
<exec seq="xeyes2" type="verbatim" ostype="xexec">xeyes</exec>
You will see the application xeyes opened in the virtual machine, but the command executed in the host will not end till the application is closed.
Or you can use a "system" command that closes (kills) all calc applications opened:
sudo vnx -f simple_ubuntu-gui.xml -v --exe calcoff
You can start or stop a web server in the virtual machine with:
sudo vnx -f /usr/share/vnx/examples/simple_ubuntu.xml -v --exe start-www sudo vnx -f /usr/share/vnx/examples/simple_ubuntu.xml -v --exe stop-www
And test that the web server is running by manually opening a web navigator in the host and loading URL http://10.0.0.5. Alternativey, you can check the server availability with "nmap" tool:
# nmap -p 80 10.0.0.5 Starting Nmap 5.00 ( http://nmap.org ) at 2011-07-28 00:48 CEST Interesting ports on 10.0.0.5: PORT STATE SERVICE 80/tcp open http MAC Address: 02:FD:00:05:01:01 (Unknown) Nmap done: 1 IP address (1 host up) scanned in 0.40 seconds
Apart from the <exec> tags which define the commands used to start the web server ("service apache2 start"), the command sequence "start-www" includes a <filetree> tag to copy files from the host to the virtual machine that it is used to copy the initial web page shown by the server.
<!-- Copy the content of conf/txtfile directory in the host to
the /var/www directory in the virtual machine -->
<filetree seq="start-www" root="/var/www">conf/txtfile</filetree>
<!-- Start/stop apache www server -->
<exec seq="start-www" type="verbatim" ostype="system">service apache2 start</exec>
<exec seq="stop-www" type="verbatim" ostype="system">service apache2 stop</exec>
You can find more example commands by having a look at <exec> and <filetree> tags in simple_ubuntu-gui.xml file or in other simple_*.xml examples. And more information about command execution in here.
Stopping the scenario
To stop the scenario preserving the changes made inside virtual machines you have to use the "-d" or "--shutdown" option:
sudo vnx -f simple_ubuntu-gui.xml -v --shutdown
You can later restart the scenario with:
sudo vnx -f simple_ubuntu-gui.xml -v --create
To stop the scenario discarding all the changes made in the virtual machine use the "-P" or "--destroy" option:
sudo vnx -f simple_ubuntu-gui.xml -v --destroy
Tipically, virtual machines in VNX are created using "Copy-on-write (COW)" filesystems to allow sharing a root filesystem among several virtual machines.
In the definition of the virtual machine:
<filesystem type="cow">/usr/share/vnx/filesystems/rootfs_ubuntu-gui</filesystem>
you specify the root filesystem to use (/usr/share/vnx/filesystems/rootfs_ubuntu-gui) and how it is mounted (cow). Using COW mode, the virtual machine will use the root filesystem in read-only mode and use another filesystem to save the files modified. When you use "-P|--destroy" option to stop an scenario, vnx deletes the filesystem with the modifications.
Other interesting options
You can see a graphical map of the virtual scenario using the --show-map option:
sudo vnx -f simple_ubuntu-gui.xml -v --show-map
simple_ubuntu-gui.xml scenario
<?xml version="1.0" encoding="UTF-8"?>
<!--
~~~~~~~~~~~~~~~~~~~~
VNX Sample scenarios
~~~~~~~~~~~~~~~~~~~~
Name: simple_ubuntu-gui
Description: Just one Ubuntu virtual machine with GUI connected to a Network named Net0 with address 10.0.0.5.
The host has an interface in Net0 with address 10.0.0.1
This simple scenario is supposed to be used for testing the different
types of virtual machines supported by VNX. You can start several simple_*.xml
scenarios and test the connectivity among virtual machines and the host, as all
scenarios share the same "Net0" network.
This file is part of the Virtual Networks over LinuX (VNX) Project distribution.
(www: http://www.dit.upm.es/vnx - e-mail: vnx@dit.upm.es)
Departamento de Ingenieria de Sistemas Telematicos (DIT)
Universidad Politecnica de Madrid
SPAIN
-->
<vnx xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:noNamespaceSchemaLocation="/usr/share/xml/vnx/vnx-2.00.xsd">
<global>
<version>2.0</version>
<scenario_name>simple_ubuntu-gui</scenario_name>
<automac offset="5"/>
<vm_mgmt type="none" />
<vm_defaults>
<console id="0" display="yes"/>
<console id="1" display="yes"/>
</vm_defaults>
</global>
<net name="Net0" mode="virtual_bridge" />
<!-- NODES -->
<vm name="ubuntu-gui" type="libvirt" subtype="kvm" os="linux">
<filesystem type="cow">/usr/share/vnx/filesystems/rootfs_ubuntu-gui</filesystem>
<mem>512M</mem>
<if id="1" net="Net0">
<ipv4>10.0.0.5/24</ipv4>
</if>
<filetree seq="vnxtxt" root="/tmp">conf/txtfile</filetree>
<filetree seq="vnxwww" root="/tmp">conf/txtfile</filetree>
<filetree seq="start-www" root="/var/www">conf/txtfile</filetree>
<!-- Start xeyes application -->
<exec seq="xeyes" type="verbatim" ostype="xexec">xeyes</exec>
<!-- Start xeyes application and wait until it is closed -->
<exec seq="xeyes2" type="verbatim" ostype="xsystem">xeyes</exec>
<!-- Start gedit, maximize the window and show a text file -->
<exec seq="vnxtxt" type="verbatim" ostype="system">chmod 666 /tmp/vnx.txt</exec>
<exec seq="vnxtxt" type="verbatim" ostype="xexec">gedit /tmp/vnx.txt</exec>
<exec seq="vnxtxt" type="verbatim" ostype="xexec">sleep 3; wmctrl -r vnx.txt -b add,maximized_vert,maximized_horz</exec>
<exec seq="vnxtxtoff" type="verbatim" ostype="system">pkill gedit; rm /tmp/vnx.*</exec>
<!-- Start firefox and load vnx.html, copied by means of a <filetree> -->
<exec seq="vnxwww" type="verbatim" ostype="system">chmod 666 /tmp/vnx.html</exec>
<exec seq="vnxwww" type="verbatim" ostype="xexec">firefox /tmp/vnx.html</exec>
<exec seq="vnxwwwoff" type="verbatim" ostype="system">pkill firefox; rm /tmp/vnx.*</exec>
<!-- Start calculator -->
<exec seq="calc" type="verbatim" ostype="xexec">gcalctool</exec>
<exec seq="calcoff" type="verbatim" ostype="system">pkill gcalctool</exec>
<!-- Start/stop apache www server -->
<exec seq="start-www" type="verbatim" ostype="system">service apache2 start</exec>
<exec seq="stop-www" type="verbatim" ostype="system">service apache2 stop</exec>
<exec seq="start-www2" type="verbatim" ostype="exec">service apache2 start</exec>
<exec seq="ping" type="verbatim" ostype="system">'ping 10.0.0.1'</exec>
<exec seq="showlog" type="verbatim" ostype="system">tail -f /var/log/vnxaced.log</exec>
<exec seq="start-www" type="verbatim" ostype="system">chmod 644 /var/www/*</exec>
</vm>
<host>
<hostif net="Net0">
<ipv4>10.0.0.1/24</ipv4>
</hostif>
</host>
</vnx>
