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Libvirt

The libvirt implementation uses backing store images. This means that the domain being cloned needs to be shut down. When cloning a system all disks of the base system are cloned using a backing store, and thrown away upon teardown, thus leaving the original system unchanged.

Machines can use static IP's using {host}.ipLookupStrategy=static. It is up to you that you do not start more than one. It is also possible to use DHCP using {host}.ipLookupStrategy=SSH. You have to specify the name of the Virtual Network in libvirt or the name of the bridge the domain is connected to and a command to lookup the IP on the DHCP server giving the system it's IP address. The IP can then be retrieved using the getHostName() method on the CloudHost.

NAT network#

Due to the way NAT works the machine would only be accessible from the Libvirt (KVM) host. Example settings for a (NAT) network named my_nat_network:

nat_host {    libvirtURL="qemu+ssh://user@linux-box/system"    libvirtBaseDomain="my_base_domain"    networkDeviceId="my_nat_network"    ipLookupStrategy="SSH"    SSH {        url="ssh://user@linux-box?os=UNIX&connectionType=SCP&privateKeyFile="${user.home}"/.ssh/id_rsa&passphrase=bigsecret"        command="""grep {0} /var/lib/libvirt/dnsmasq/my_nat_network.leases | cut -d " " -f 3"""        timeout=30    }}

Bridged network#

Example settings for a host connected to a bridge named br0. Assuming a DHCP server dhcp-box:

bridged_host {    libvirtURL="qemu+ssh://user@linux-box/system"    libvirtBaseDomain="my_base_domain"    networkDeviceId="br0"    ipLookupStrategy="SSH"    SSH {        url="ssh://dhcp-query-user@dhcp-box?os=UNIX&connectionType=SCP&privateKeyFile="${user.home}"/.ssh/id_rsa&passphrase=bigsecret"        command="""grep {0} /var/lib/dnsmasq/dnsmasq.leases | cut -d " " -f 3"""        timeout=30    }}

Routed network#

A routed network is similar to a bridged network with the difference that networkDeviceId should be set to the name of the routed network.

File system mapping#

With entries in the {host}.fsMapping section it is possible to mount directories from the host in the created domain. For instance like:

my-host {    ...    fsMapping {        vagrant { hostPath = ${itest.vagrantDir}"/itest/vagrant", readOnly = true }        data    { hostPath = ${itest.dataDir}, readOnly = true, accessMode = "mapped" }    }}

These mappings can be mounted on the domain with fstab entries like:

data            /data               9p    ro,trans=virtiovagrant         /vagrant            9p    ro,trans=virtio

For details on the accessMode variants see: http://libvirt.org/formatdomain.html#elementsFilesystems.

It may be necessary to add the 9p file system drivers to the initrd image of the base domain image.