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Setup kvm » Historie » Version 2

Jeremias Keihsler, 12.01.2017 11:33

1 1 Jeremias Keihsler
h1. KVM
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this is for a vanilla CentOS 7 minimal installation,
4 2 Jeremias Keihsler
largely based on @kvm_virtualization_in_rhel_7_made_easy.pdf@
5 1 Jeremias Keihsler
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good information is also found at http://virtuallyhyper.com/2013/06/migrate-from-libvirt-kvm-to-virtualbox/
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h2. basic updates/installs
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<pre><code class="bash">
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yum update
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yum install wget
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yum install vim
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reboot
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</code></pre>
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h2. check machine capability
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<pre><code class="bash">
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grep -E 'svm|vmx' /proc/cpuinfo
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</code></pre>
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vmx ... Intel
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svm ... AMD
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h2. install KVM on CentOS minimal
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<pre><code class="bash">
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yum install yum install qemu-kvm libvirt libvirt-python libguestfs-tools virt-install
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systemctl enable libvirtd && systemctl start libvirtd
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</code></pre>
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verify the following kernel modules are loaded
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<pre><code class="bash">
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lsmod | grep kvm
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</code></pre>
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<pre><code class="bash">
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kvm
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kvm_intel
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</code></pre>
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h2. setup networking
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add to the network controller configuration file @/etc/sysconfig/network-scripts/ifcfg-em1@
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<file /etc/sysconfig/network-scripts/ifcfg-em1>
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...
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BRIDGE=br0
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</pre>
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add following new file @/etc/sysconfig/network-scripts/ifcfg-br0@
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<file /etc/sysconfig/network-scripts/ifcfg-br0>
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DEVICE="br0"
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# BOOTPROTO is up to you. If you prefer “static”, you will need to
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# specify the IP address, netmask, gateway and DNS information.
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BOOTPROTO="dhcp"
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IPV6INIT="yes"
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IPV6_AUTOCONF="yes"
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ONBOOT="yes"
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TYPE="Bridge"
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DELAY="0"
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</pre>
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enable network forwarding @/etc/sysctl.conf@
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<file /etc/sysctl.conf>
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...
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net.ipv4.ip_forward = 1
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</pre>
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read the file and restart NetworkManager
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<pre><code class="bash">
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sysctl -p /etc/sysctl.conf
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systemctl restart NetworkManager
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</code></pre>
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h2. can KVM and Virtualbox coexist
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http://www.dedoimedo.com/computers/kvm-virtualbox.html
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h2. convert Virtualbox to KVM
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h3. uninstall Virtualbox-guest-additions
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<pre><code class="bash">
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opt/[VboxAddonsFolder]/uninstall.sh
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</code></pre>
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some people had to remove @/etc/X11/xorg.conf@
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h3. convert image from Virtualbox to KWM
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<pre><code class="bash">
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VBoxManage clonehd --format RAW Virt_Image.vdi Virt_Image.img
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</code></pre>
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RAW-Datei nach qcow konvertieren
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<pre><code class="bash">
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qemu-img convert -f raw Virt_Image.img -O qcow2 Virt_Image.qcow
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</code></pre>
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h2. automatic start/shutdown of VMs with Host
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taken from https://access.redhat.com/documentation/en-US/Red_Hat_Enterprise_Linux/6/html/Virtualization_Administration_Guide/sub-sect-Shutting_down_rebooting_and_force_shutdown_of_a_guest_virtual_machine-Manipulating_the_libvirt_guests_configuration_settings.html
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h3. enable libvirt-guests service
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<pre><code class="bash">
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systemctl enable libvirt-guests
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systemctl start libvirt-guests
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</code></pre>
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all settings are to be done in @/etc/sysconfig/libvirt-guests@
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h2. install
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<pre><code class="bash">
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yum install virt-manager
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</code></pre>
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<pre><code class="bash">
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usermod -a -G libvirt username
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</code></pre>
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h2. rename KVM-guest
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taken from http://www.taitclarridge.com/techlog/2011/01/rename-kvm-virtual-machine-with-virsh.html
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Power off the virtual machine and export the machine's XML configuration file:
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<pre><code class="bash">
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virsh dumpxml name_of_vm > name_of_vm.xml
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</code></pre>
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Next, edit the XML file and change the name between the <name></name> tags (should be right near the top). As an added step you could also rename the disk file to reflect the change of the name and change the name of it in the <devices> section under <source file='/path/to/name_of_vm.img'>.
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Save the XML file and undefine the old VM name with:
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<pre><code class="bash">
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virsh undefine name_of_vm
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</code></pre>
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Now just import the edited XML file to define the VM:
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<pre><code class="bash">
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virsh define name_of_vm.xml
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</code></pre>
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And that should be it! You can now start up your vm either in the Virtual Machine Manager or with virsh using:
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<pre><code class="bash">
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virsh start name_of_vm
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</code></pre>
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h2. set fixed IP-adr via DHCP (default-network)
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taken from https://wiki.libvirt.org/page/Networking
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<pre><code class="bash">
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virsh edit <guest>
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</code></pre>
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where <guest> is the name or uuid of the guest. Add the following snippet of XML to the config file: 
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<pre><code class="bash">
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<interface type='network'>
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  <source network='default'/>
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  <mac address='00:16:3e:1a:b3:4a'/>
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</interface>
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</code></pre>
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Applying modifications to the network
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Sometimes, one needs to edit the network definition and apply the changes on the fly. The most common scenario for this is adding new static MAC+IP mappings for the network's DHCP server. If you edit the network with "virsh net-edit", any changes you make won't take effect until the network is destroyed and re-started, which unfortunately will cause a all guests to lose network connectivity with the host until their network interfaces are explicitly re-attached.
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virsh net-update
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Fortunately, many changes to the network configuration (including the aforementioned addition of a static MAC+IP mapping for DHCP) can be done with "virsh net-update", which can be told to enact the changes immediately. For example, to add a DHCP static host entry to the network named "default" mapping MAC address 53:54:00:00:01 to IP address 192.168.122.45 and hostname "bob", you could use this command: 
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<pre><code class="bash">
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virsh net-update default add ip-dhcp-host \
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          "<host mac='52:54:00:00:00:01' \
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           name='bob' ip='192.168.122.45' />" \
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           --live --config
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</code></pre>
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h2. forwarding incoming connections
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taken from https://wiki.libvirt.org/page/Networking
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By default, guests that are connected via a virtual network with <forward mode='nat'/> can make any outgoing network connection they like. Incoming connections are allowed from the host, and from other guests connected to the same libvirt network, but all other incoming connections are blocked by iptables rules.
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If you would like to make a service that is on a guest behind a NATed virtual network publicly available, you can setup libvirt's "hook" script for qemu to install the necessary iptables rules to forward incoming connections to the host on any given port HP to port GP on the guest GNAME:
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1) Determine a) the name of the guest "G" (as defined in the libvirt domain XML), b) the IP address of the guest "I", c) the port on the guest that will receive the connections "GP", and d) the port on the host that will be forwarded to the guest "HP".
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(To assure that the guest's IP address remains unchanged, you can either configure the guest OS with static ip information, or add a <host> element inside the <dhcp> element of the network that is used by your guest. See the libvirt network XML documentation address section for defails and an example.)
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2) Stop the guest if it's running.
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3) Create the file /etc/libvirt/hooks/qemu (or add the following to an already existing hook script), with contents similar to the following (replace GNAME, IP, GP, and HP appropriately for your setup):
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Use the basic script below or see an "advanced" version, which can handle several different machines and port mappings here (improvements are welcome) or here's a python script which does a similar thing and is easy to understand and configure (improvements are welcome): 
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<pre>
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#!/bin/bash
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# used some from advanced script to have multiple ports: use an equal number of guest and host ports
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# Update the following variables to fit your setup
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Guest_name=GUEST_NAME
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Guest_ipaddr=GUEST_IP
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Host_ipaddr=HOST_IP
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Host_port=(  'HOST_PORT1' 'HOST_PORT2' )
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Guest_port=( 'GUEST_PORT1' 'GUEST_PORT2' )
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length=$(( ${#Host_port[@]} - 1 ))
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if [ "${1}" = "${Guest_name}" ]; then
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   if [ "${2}" = "stopped" ] || [ "${2}" = "reconnect" ]; then
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       for i in `seq 0 $length`; do
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               iptables -t nat -D PREROUTING -d ${Host_ipaddr} -p tcp --dport ${Host_port[$i]} -j DNAT --to ${Guest_ipaddr}:${Guest_port[$i]}
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               iptables -D FORWARD -d ${Guest_ipaddr}/32 -p tcp -m state --state NEW -m tcp --dport ${Guest_port[$i]} -j ACCEPT
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       done
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   fi
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   if [ "${2}" = "start" ] || [ "${2}" = "reconnect" ]; then
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       for i in `seq 0 $length`; do
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               iptables -t nat -A PREROUTING -d ${Host_ipaddr} -p tcp --dport ${Host_port[$i]} -j DNAT --to ${Guest_ipaddr}:${Guest_port[$i]}
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               iptables -I FORWARD -d ${Guest_ipaddr}/32 -p tcp -m state --state NEW -m tcp --dport ${Guest_port[$i]} -j ACCEPT
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       done
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   fi
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fi
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</pre>
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4) chmod +x /etc/libvirt/hooks/qemu
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5) Restart the libvirtd service.
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6) Start the guest.
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(NB: This method is a hack, and has one annoying flaw in versions of libvirt prior to 0.9.13 - if libvirtd is restarted while the guest is running, all of the standard iptables rules to support virtual networks that were added by libvirtd will be reloaded, thus changing the order of the above FORWARD rule relative to a reject rule for the network, hence rendering this setup non-working until the guest is stopped and restarted. Thanks to the new "reconnect" hook in libvirt-0.9.13 and newer (which is used by the above script if available), this flaw is not present in newer versions of libvirt (however, this hook script should still be considered a hack). 
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h2. wrapper script for virsh
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240 2 Jeremias Keihsler
<pre>
241 1 Jeremias Keihsler
#! /bin/sh
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# kvm_control   Startup script for KVM Virtual Machines
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#
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# description: Manages KVM VMs
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# processname: kvm_control.sh
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#
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# pidfile: /var/run/kvm_control/kvm_control.pid
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#
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### BEGIN INIT INFO
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#
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### END INIT INFO
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#
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# Version 20161228 by Jeremias Keihsler based on:
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# virsh-specific parts are taken from:
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#  https://github.com/kumina/shutdown-kvm-guests/blob/master/shutdown-kvm-guests.sh
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# Version 20110509 by Jeremias Keihsler (vboxcontrol) based on:
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# Version 20090301 by Kevin Swanson <kswan.info> based on:
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# Version 2008051100 by Jochem Kossen <jochem.kossen@gmail.com>
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# http://farfewertoes.com
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#
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# Released in the public domain
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#
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# This file came with a README file containing the instructions on how
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# to use this script.
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# 
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# this is no more to be used as an init.d-script (vboxcontrol was an init.d-script)
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#
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################################################################################
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# INITIAL CONFIGURATION
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export PATH="${PATH:+$PATH:}/bin:/usr/bin:/usr/sbin:/sbin"
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VIRSH=/usr/bin/virsh
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TIMEOUT=300
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declare -i VM_isrunning
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################################################################################
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# FUNCTIONS
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log_failure_msg() {
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echo $1
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}
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log_action_msg() {
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echo $1
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}
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# list running domains
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list_running_domains() {
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  $VIRSH list | grep running | awk '{ print $2}'
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}
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# Check for running machines every few seconds; return when all machines are
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# down
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wait_for_closing_machines() {
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RUNNING_MACHINES=`list_running_domains | wc -l`
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if [ $RUNNING_MACHINES != 0 ]; then
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  log_action_msg "machines running: "$RUNNING_MACHINES
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  sleep 2
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  wait_for_closing_machines
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fi
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}
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################################################################################
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# RUN
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case "$1" in
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  start)
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    if [ -f /etc/kvm_box/machines_enabled_start ]; then
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      cat /etc/kvm_box/machines_enabled_start | while read VM; do
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        log_action_msg "Starting VM: $VM ..."
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        $VIRSH start $VM
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        sleep 20
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        RETVAL=$?
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      done
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      touch /tmp/kvm_control
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    fi
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  ;;
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  stop)
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    # NOTE: this stops first the listed VMs in the given order
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    # and later all running VM's. 
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    # After the defined timeout all remaining VMs are killed
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    # Create some sort of semaphore.
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    touch /tmp/shutdown-kvm-guests
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    echo "Try to cleanly shut down all listed KVM domains..."
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    # Try to shutdown each listed domain, one by one.
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    if [ -f /etc/kvm_box/machines_enabled_stop ]; then
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      cat /etc/kvm_box/machines_enabled_stop | while read VM; do
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        log_action_msg "Shutting down VM: $VM ..."
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        $VIRSH shutdown $VM --mode acpi
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        sleep 10
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        RETVAL=$?
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      done
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    fi
340
    sleep 10
341
    
342
    echo "Try to cleanly shut down all running KVM domains..."
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    # Try to shutdown each remaining domain, one by one.
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    list_running_domains | while read VM; do
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      log_action_msg "Shutting down VM: $VM ..."
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      $VIRSH shutdown $VM --mode acpi
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      sleep 10
348
    done
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    # Wait until all domains are shut down or timeout has reached.
351
    END_TIME=$(date -d "$TIMEOUT seconds" +%s)
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    while [ $(date +%s) -lt $END_TIME ]; do
354
      # Break while loop when no domains are left.
355
      test -z "$(list_running_domains)" && break
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      # Wait a litte, we don't want to DoS libvirt.
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      sleep 2
358
    done
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    # Clean up left over domains, one by one.
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    list_running_domains | while read DOMAIN; do
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      # Try to shutdown given domain.
363
      $VIRSH destroy $DOMAIN
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      # Give libvirt some time for killing off the domain.
365
      sleep 10
366
    done
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    wait_for_closing_machines
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    rm -f /tmp/shutdown-kvm-guests
370
    rm -f /tmp/kvm_control
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  ;;
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  export)
373
    JKE_DATE=$(date +%F)
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    if [ -f /etc/kvm_box/machines_enabled_export ]; then
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      cat /etc/kvm_box/machines_enabled_export  | while read VM; do
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        rm -f /tmp/kvm_control_VM_isrunning
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        VM_isrunning=0
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        list_running_domains | while read RVM; do
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          #echo "VM list -$VM- : -$RVM-"
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          if [[ "$VM" ==  "$RVM" ]]; then 
381
            #echo "VM found running..."
382
            touch /tmp/kvm_control_VM_isrunning
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            VM_isrunning=1
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            #echo "$VM_isrunning"
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            break
386
          fi
387
          #echo "$VM_isrunning"
388
        done 
389
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        # took me a while to figure out that the above 'while'-loop 
391
        # runs in a separate process ... let's use the 'file' as a 
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        # kind of interprocess-communication :-) JKE 20161229
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        if [ -f /tmp/kvm_control_VM_isrunning ]; then
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          VM_isrunning=1
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        fi
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        rm -f /tmp/kvm_control_VM_isrunning
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398
        #echo "VM status $VM_isrunning"
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        if [ "$VM_isrunning" -ne 0 ]; then 
400
          log_failure_msg "Exporting VM: $VM is not possible, it's running ..."
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        else
402
          log_action_msg "Exporting VM: $VM ..."
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          VM_BAK_DIR="$VM"_"$JKE_DATE"
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          mkdir "$VM_BAK_DIR"
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          $VIRSH dumpxml $VM > ./$VM_BAK_DIR/$VM.xml
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          $VIRSH -q domblklist $VM | awk '{ print$2}' | while read VMHDD; do
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            echo "$VM hdd=$VMHDD"
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            if [ -f "$VMHDD" ]; then
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              rsync --progress $VMHDD ./$VM_BAK_DIR/`basename $VMHDD`
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            else
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              log_failure_msg "Exporting VM: $VM image-file $VMHDD not found ..."
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            fi
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          done
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        fi
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      done
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    else
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      log_action_msg "export-list not found"
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    fi
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  ;;
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  start-vm)
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    log_action_msg "Starting VM: $2 ..."
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    $VIRSH start $2
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    RETVAL=$?
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  ;;
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  stop-vm)
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    log_action_msg "Stopping VM: $2 ..."
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    $VIRSH shutdown $2 --mode acpi
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    RETVAL=$?
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  ;;
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  poweroff-vm)
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    log_action_msg "Powering off VM: $2 ..."
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    $VIRSH destroy $2
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    RETVAL=$?
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  ;;
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  export-vm)
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    # NOTE: this exports the given VM
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    log_action_msg "Exporting VM: $2 ..."
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    rm -f /tmp/kvm_control_VM_isrunning
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    VM_isrunning=0
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    JKE_DATE=$(date +%F)
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    list_running_domains | while read RVM; do
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      #echo "VM list -$VM- : -$RVM-"
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      if [[ "$2" ==  "$RVM" ]]; then 
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        #echo "VM found running..."
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        touch /tmp/kvm_control_VM_isrunning
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        VM_isrunning=1
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        #echo "$VM_isrunning"
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        break
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      fi
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      #echo "$VM_isrunning"
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    done 
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    # took me a while to figure out that the above 'while'-loop 
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    # runs in a separate process ... let's use the 'file' as a 
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    # kind of interprocess-communication :-) JKE 20161229
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    if [ -f /tmp/kvm_control_VM_isrunning ]; then
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      VM_isrunning=1
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    fi
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    rm -f /tmp/kvm_control_VM_isrunning
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    #echo "VM status $VM_isrunning"
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    if [ "$VM_isrunning" -ne 0 ]; then 
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      log_failure_msg "Exporting VM: $VM is not possible, it's running ..."
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    else
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      log_action_msg "Exporting VM: $VM ..."
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      VM_BAK_DIR="$2"_"$JKE_DATE"
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      mkdir "$VM_BAK_DIR"
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      $VIRSH dumpxml $2 > ./$VM_BAK_DIR/$2.xml
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      $VIRSH -q domblklist $2 | awk '{ print$2}' | while read VMHDD; do
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        echo "$2 hdd=$VMHDD"
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        if [ -f "$VMHDD" ]; then
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          rsync --progress $VMHDD ./$VM_BAK_DIR/`basename $VMHDD`
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        else
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          log_failure_msg "Exporting VM: $2 image-file $VMHDD not found ..."
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        fi
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      done
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    fi
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  ;;
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  status)
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    echo "The following virtual machines are currently running:"
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    list_running_domains | while read VM; do
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      echo -n "  $VM"
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      echo " ... is running"
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    done
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  ;;
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  *)
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    echo "Usage: $0 {start|stop|status|export|start-vm <VM name>|stop-vm <VM name>|poweroff-vm <VM name>}|export-vm <VMname>"
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    echo "  start      start all VMs listed in '/etc/kvm_box/machines_enabled_start'"
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    echo "  stop       1st step: acpi-shutdown all VMs listed in '/etc/kvm_box/machines_enabled_stop'"
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    echo "             2nd step: acpi-shutdown all running VMs"
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    echo "             3nd step: wait for all machines shutdown or $TIMEOUT s"
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    echo "             4nd step: destroy all sitting VMs"
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    echo "  status     list all running VMs"
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    echo "  export     export all VMs listed in '/etc/kvm_box/machines_enabled_export' to the current directory"
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    echo "  start-vm <VM name>     start the given VM"
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    echo "  stop-vm <VM name>      acpi-shutdown the given VM"
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    echo "  poweroff-vm <VM name>  poweroff the given VM"
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    echo "  export-vm <VM name>    export the given VM to the current directory"
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    exit 3
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esac
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exit 0
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</pre>