Open Virtualization Format (OVF) is an open standard for packaging and distributing virtual appliances or more generally software to be run in virtual machines. The standard describes an “open, secure, portable, efficient and extensible format for the packaging and distribution of software to be run in virtual machines”. The OVF standard is not tied to any particular hypervisor or processor architecture. The unit of packaging and distribution is a so-called OVF Package which may contain one or more virtual systems each of which can be deployed to a virtual machine.

An OVF package consists of several files placed in one directory. An OVF package always contains exactly one OVF descriptor (a file with extension .ovf). The OVF descriptor is an XML file which describes the packaged virtual machine; it contains the metadata for the OVF package, such as name, hardware requirements, references to the other files in the OVF package and human-readable descriptions. In addition to the OVF descriptor, the OVF package will typically contain one or more disk images, and optionally certificate files and other auxiliary files.

The entire directory can be distributed as an OVA package, which is a tar archive file with the OVF directory inside.

OVF references used

• OVF 2.0 standard - http://www.dmtf.org/sites/default/files/standards/documents/DSP0243_2.0.0.pdf
• Abiquo OVF reference - http://wiki.abiquo.com/display/ABI24/OVF+Reference
• Ganeti OVF reference - http://docs.ganeti.org/ganeti/2.6/html/design-ovf-support.html
• oVirt/RHEV OVF reference - http://www.ovirt.org/Ovf

OVF 2.0 descriptor structure

The OVF description file (.ovf) contains metadata of the virtual appliance template. Envelope is the root element for this XML document.

The mandatory sections are:

• References
• DiskSection
• VirtualSystem or VirtualSystemCollection (multi-VM)
  • ProductSection
  • VirtualHardwareSection

Envelope example

<?xml version="1.0" encoding="UTF-8"?>
<Envelope 
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xmlns:vssd="http://schemas.dmtf.org/wbem/wscim/1/cim-schema/2/CIM_VirtualSystemSettingData"
    xmlns:rasd="http://schemas.dmtf.org/wbem/wscim/1/cim-schema/2/CIM_ResourceAllocationSettingData"
    xmlns:ovf="http://schemas.dmtf.org/ovf/envelope/2"
    xmlns="http://schemas.dmtf.org/ovf/envelope/2"
    xml:lang="en-US">
    <References></References>
    <DiskSection></DiskSection>
    <NetworkSection></NetworkSection>
    <VirtualSystem>
        <Info></Info>
        <Name></Name>
        <OperatingSystemSection></OperatingSystemSection>
        <VirtualHardwareSection><VirtualHardwareSection>
    </VirtualSystem>
</Envelope>

References (required)

This section contains references to external resources used by the virtual appliance. References can point to files such as virtual disks or icons.

References example

<References>
    <File ovf:id="file1" ovf:href="vmdisk1.vmdk" ovf:size="180114671"/>
    <File ovf:id="file2" ovf:href="vmdisk2.vmdk" ovf:size="4882023564" ovf:chunkSize="2147483648"/>
    <File ovf:id="file3" ovf:href="resource.iso" ovf:size="212148764" ovf:compression="gzip"/>
    <File ovf:id="icon" ovf:href="icon.png" ovf:size="1360"/>
</References>

DiskSection (required)

A DiskSection describes meta-information about virtual disks in the OVF package. Virtual disks and their metadata are described outside the virtual hardware to facilitate sharing between virtual machines within an OVF package. Virtual disks in DiskSection can be referenced by multiple virtual machines, but seen from the guest software each virtual machine get individual private disks. Any level of sharing done at runtime is deployment platform specific and not visible to the guest software.

DiskSection example

<DiskSection>
    <Info>List of Virtual Disks</Info>
    <Disk 
        ovf:fileRef="file1"
        ovf:diskId="disk1"
        ovf:capacity="4294967296"
        ovf:populatedSize="1090890" 
        ovf:format="http://people.gnome.org/~markmc/qcow-image-format.html#monolithic_sparse" />
</DiskSection>

Disk formats

VirtualSystem (Single-VM, required)

The VirtualSystem describes the template configuration for a virtual machine.

VirtualSystem example

<VirtualSystem ovf:id="centos-6-x86_64">
    <Info>OpenNode QEMU/KVM VM template</Info>
    <Name>CentOS 6 Appliance</Name>
    <ProductSection>
    </ProductSection>
    <VirtualHardwareSection>
    </VirtualHardwareSection>
    <OperatingSystemSection>
    </OperatingSystemSection>
</VirtualSystem>

VirtualSystemCollection (multi-VM)

VirtualSystemCollection example

<VirtualSystemCollection ovf:id="multi-tier-app">
    <Info>A collection of virtual machines</Info>
    <Name>Multi-tiered Appliance</Name>
    <SomeSection>
        <!-- Additional section content -->
    </SomeSection>
    <!-- Additional sections can follow -->
    <VirtualSystem ovf:id="...">
    <!-- Additional sections -->
    </VirtualSystem>
    <!-- Additional VirtualSystem or VirtualSystemCollection elements can follow-->
</VirtualSystemCollection>

OperatingSystemSection

OVF spec says:

• The values for ovf:id should be taken from the ValueMap of the CIM_OperatingSystem.OsType property.
• The description should be taken from the corresponding Values of the CIM_OperatingSystem.OsType property.

NB! We do mapping from CIM types to OpenVZ/Libvirt supported distros with the help of OtherTypeDescription and Version fields for CIM unsupported distros

CIM OsType value map

"Unknown" [0]
"Other" [1]
"MACOS" [2]
"ATTUNIX" [3]
"DGUX" [4]
"DECNT" [5]
"Tru64 UNIX" [6]
"OpenVMS" [7]
"HPUX" [8]
"AIX" [9]
"MVS" [10]
"OS400" [11]
"OS/2" [12]
"JavaVM" [13]
"MSDOS" [14]
"WIN3x" [15]
"WIN95" [16]
"WIN98" [17]
"WINNT" [18]
"WINCE" [19]
"NCR3000" [20]
"NetWare" [21]
"OSF" [22]
"DC/OS" [23]
"Reliant UNIX" [24]
"SCO UnixWare" [25]
"SCO OpenServer" [26]
"Sequent" [27]
"IRIX" [28]
"Solaris" [29]
"SunOS" [30]
"U6000" [31]
"ASERIES" [32]
"HP NonStop OS" [33]
"HP NonStop OSS" [34]
"BS2000" [35]
"LINUX" [36]
"Lynx" [37]
"XENIX" [38]
"VM" [39]
"Interactive UNIX" [40]
"BSDUNIX" [41]
"FreeBSD" [42]
"NetBSD" [43]
"GNU Hurd" [44]
"OS9" [45]
"MACH Kernel" [46]
"Inferno" [47]
"QNX" [48]
"EPOC" [49]
"IxWorks" [50]
"VxWorks" [51]
"MiNT" [52]
"BeOS" [53]
"HP MPE" [54]
"NextStep" [55]
"PalmPilot" [56]
"Rhapsody" [57]
"Windows 2000" [58]
"Dedicated" [59]
"OS/390" [60]
"VSE" [61]
"TPF" [62]
"Windows (R) Me" [63]
"Caldera Open UNIX" [64]
"OpenBSD" [65]
"Not Applicable" [66]
"Windows XP" [67]
"z/OS" [68]
"Microsoft Windows Server 2003" [69]
"Microsoft Windows Server 2003 64-Bit" [70]
"Windows XP 64-Bit" [71]
"Windows XP Embedded" [72]
"Windows Vista" [73]
"Windows Vista 64-Bit" [74]
"Windows Embedded for Point of Service" [75]
"Microsoft Windows Server 2008" [76]
"Microsoft Windows Server 2008 64-Bit" [77]
"FreeBSD 64-Bit" [78]
"RedHat Enterprise Linux" [79]
"RedHat Enterprise Linux 64-Bit" [80]
"Solaris 64-Bit" [81]
"SUSE" [82]
"SUSE 64-Bit" [83]
"SLES" [84]
"SLES 64-Bit" [85]
"Novell OES" [86]
"Novell Linux Desktop" [87]
"Sun Java Desktop System" [88]
"Mandriva" [89]
"Mandriva 64-Bit" [90]
"TurboLinux" [91]
"TurboLinux 64-Bit" [92]
"Ubuntu" [93]
"Ubuntu 64-Bit" [94]
"Debian" [95]
"Debian 64-Bit" [96]
"Linux 2.4.x" [97]
"Linux 2.4.x 64-Bit" [98]
"Linux 2.6.x" [99]
"Linux 2.6.x 64-Bit" [100]
"Linux 64-Bit" [101]
"Other 64-Bit" [102]
"Microsoft Windows Server 2008 R2" [103]

OpenVZ distro map

Libvirt distro map

OperatingSystemSection examples

CIM supported  Specifies the operating system installed RedHat Enterprise Linux 64-Bit 6.4

CIM Other  Specifies the operating system installed CentOS 64-bit</Description> 6.4 </OperatingSystemSection>

ProductSection

ProductSection example

<ProductSection>
    <Info>OpenNode OpenVZ CT Template</Info>
    <Product>CentOS 6 Appliance</Product>
    <Icon ovf:fileRef="http://opennodecloud.com/templates/openvz/centos-6-x86_64.png" ovf:mimeType="image/png" ovf:width="32" ovf:height="32" />
    <Category>OS properties</Category>
    <Property ovf:key="admin.email" ovf:type="string" ovf:userConfigurable="true">
        <Label>Admin email</Label>
        <Description>Email address of administrator</Description>
    </Property>
    <Category>Admin properties</Category>
    <Property ovf:key="app_ip" ovf:type="string" ovf:value="${appserver-vm}">
        <Description>IP address of the application server VM</Description>
    </Property>      
</ProductSection>

VirtualHardwareSection

Contains all the information about the hardware resources needed to run the virtual appliance. The System section is followed by various Items. In VirtualHardwareSection, virtual disk devices may have a rasd:HostResource element referring to a Disk element in DiskSection.

VirtualHardWareSection example

<VirtualHardwareSection>
    <System><vssd:VirtualSystemType>openvz</vssd:VirtualSystemType></System>
    <Item>...</Item>
    ...
    <Item>...</Item>
</VirtualHardwareSection>

Items

In the System section, an Item specifies a virtual device by describing the resources to allocate on the virtual system. Resources are described using using Resource Allocation Setting Data (RASD) elements.

Required Items:

• Virtual CPU
• Virtual Memory
• Hard Disk

Optional Items:

• Disk Controller
• Ethernet Adapter(s)

Common Item RASD Fields

These RASD fields are found in all items:

• rasd:Caption: Brief description to make the OVF more readable.
• rasd:InstanceID: A unique ID for the Item.

Min/max items

Items boundaries can be specified by giving ovf:bound argument to Item element. ovf:bound could be: normal, min, max

CIM ResourceType ValueMap

Virtual CPU

Reference information for completing the Virtual CPU Item:

• rasd:ResourceType: Set to “3” to indicate this is a CPU.
• rasd:VirtualQuantity: The number of virtual CPUs allocated.

<Item ovf:bound="normal">
    <rasd:Caption>1 virtual CPUs</rasd:Caption>
    <rasd:Description>Number of virtual CPUs</rasd:Description>
    <rasd:InstanceId>1</rasd:InstanceId>
    <rasd:ResourceType>3</rasd:ResourceType>
    <rasd:VirtualQuantity>1</rasd:VirtualQuantity>
</Item>
<Item ovf:bound="min">
    <rasd:Caption>1 virtual CPUs</rasd:Caption>
    <rasd:Description>Number of virtual CPUs</rasd:Description>
    <rasd:InstanceId>2</rasd:InstanceId>
    <rasd:ResourceType>3</rasd:ResourceType>
    <rasd:VirtualQuantity>1</rasd:VirtualQuantity>
</Item>

Virtual Memory

Reference information for completing the RAM Item:

• rasd:ResourceType: Set to “4” to indicate this is RAM.
• rasd:AllocationUnits: Default is “bytes”. Other options are:
  • “KB”, “KILOBYTE” or “byte * 2^10”
  • “MB”, “MEGABYTE” or “byte * 2^20”
  • “GB”, “GIGABYTE” or “byte * 2^30”
  • “TB”, “TERABYTE” or “byte * 2^40”
• rasd:VirtualQuantity: The number of units of RAM allocated.

<Item ovf:bound="normal">
     <rasd:AllocationUnits>GB</rasd:AllocationUnits>
     <rasd:Caption>0.5 GB of memory</rasd:Caption>
     <rasd:Description>Memory Size</rasd:Description>
     <rasd:ElementName>0.5 GB of memory</rasd:ElementName>
     <rasd:InstanceID>3</rasd:InstanceID>
     <rasd:ResourceType>4</rasd:ResourceType>
     <rasd:VirtualQuantity>0.5</rasd:VirtualQuantity>
</Item>
<Item ovf:bound="min">
     <rasd:AllocationUnits>GB</rasd:AllocationUnits>
     <rasd:Caption>0.25 GB of memory</rasd:Caption>
     <rasd:Description>Memory Size</rasd:Description>
     <rasd:ElementName>0.25 GB of memory</rasd:ElementName>
     <rasd:InstanceID>4</rasd:InstanceID>
     <rasd:ResourceType>4</rasd:ResourceType>
     <rasd:VirtualQuantity>0.25</rasd:VirtualQuantity>
</Item>

Disk Controller

Supported controllers are IDE or SCSI/VirtIO. If the inserted virtual machine template has an DiskController it will be used, otherwise check the property to determine the default value.

scsi/virtio>

<Item>
    <rasd:Description>SCSI Controller</rasd:Description>
    <rasd:ElementName>SCSI controller 0</rasd:ElementName>
    <rasd:ResourceType>6</rasd:ResourceType>
    <rasd:InstanceID>5</rasd:InstanceID>
    <rasd:ResourceSubType>virtio</rasd:ResourceSubType>
</Item>

scsi/scsi

<Item>
    <rasd:Description>SCSI Controller</rasd:Description>
    <rasd:ElementName>SCSI controller 0</rasd:ElementName>
    <rasd:ResourceType>6</rasd:ResourceType>
    <rasd:InstanceID>5</rasd:InstanceID>
    <rasd:ResourceSubType>scsi</rasd:ResourceSubType>
</Item>

ide

<Item>
    <rasd:Description>IDE Controller</rasd:Description>
    <rasd:ElementName>IDE controller 0</rasd:ElementName>
    <rasd:ResourceType>5</rasd:ResourceType>
    <rasd:InstanceID>5</rasd:InstanceID>
</Item>

Hard Disk

A hard disk that is appropriate for your hypervisor and virtual machine. Reference information for completing the Hard Disk Item:

• rasd:HostResource: Reference to the disk ID of a disk defined in the DiskSection above (ovf:/disk/).

• rasd:ResourceType: Set ResourceType to 17 to indicate a hard disk

• rasd:Parent: Reference (parent) Disk Controller InstanceID (if any)

<Item>
    <rasd:Caption>Harddisk 0</rasd:Caption>
    <rasd:InstanceId>6</rasd:InstanceId>
    <rasd:Parent>5</rasd:Parent>
    <rasd:ResourceType>17</rasd:ResourceType>
    <rasd:HostResource>ovf:/disk/disk1</rasd:HostResource>
    <rasd:AllocationUnits>GB</rasd:AllocationUnits>
    <rasd:Reservation>10</rasd:Reservation>
</Item>

Ethernet Adapter

• The QEMU/KVM supported drivers are: rtl8139 (100Mbit), e1000 (1Gbit) and virtio (10Gbit)

• The OpenVZ supported drivers are: venet (routed), veth (bridged)

• Drivers are specified as ResourceSubType strings

QEMU/KVM

<Item>
    <rasd:Caption>vNic Driver</rasd:Caption>
    <rasd:ElementName>eth0</rasd:ElementName>
    <rasd:Description>Ethernet Adapter</rasd:Description>
    <rasd:InstanceId>7</rasd:InstanceId>
    <rasd:ResourceType>10</rasd:ResourceType>
    <rasd:Connection>bridged</rasd:Connection>
    <rasd:ResourceSubType>virtio</rasd:ResourceSubType>
</Item>

OpenVZ/veth

<Item>
    <rasd:Caption>vNic Driver</rasd:Caption>
    <rasd:ElementName>eth0</rasd:ElementName>
    <rasd:Description>Ethernet Adapter</rasd:Description>
    <rasd:InstanceId>7</rasd:InstanceId>
    <rasd:ResourceType>10</rasd:ResourceType>
    <rasd:Connection>bridged</rasd:Connection>
    <rasd:ResourceSubType>veth</rasd:ResourceSubType>
</Item>

OpenVZ/venet

<Item>
    <rasd:Caption>vNic Driver</rasd:Caption>
    <rasd:ElementName>venet0</rasd:ElementName>
    <rasd:Description>Ethernet Adapter</rasd:Description>
    <rasd:InstanceId>7</rasd:InstanceId>
    <rasd:ResourceType>10</rasd:ResourceType>
    <rasd:Connection>routed</rasd:Connection>
    <rasd:ResourceSubType>venet</rasd:ResourceSubType>
</Item>

QEMU/OpenVZ - alias

<!-- ElementName: Alias ID (0,1,etc - eg eth0:0, venet0:1, etc) -->
<!-- Interface name coming from Parent->ElementName -->
<!-- Parent: Ethernet Adapter InstanceID -->
<!-- NB! venet aliases must start from '1' as venet0:0 already exists for default ip -->
<Item>
    <rasd:Caption>vNic Alias</rasd:Caption>
    <rasd:ElementName>0</rasd:ElementName>
    <rasd:Description>Ethernet Adapter Alias</rasd:Description>
    <rasd:InstanceId>8</rasd:InstanceId>
    <rasd:Parent>7</rasd:Parent>
    <rasd:ResourceType>11</rasd:ResourceType>
    <rasd:ResourceSubType>alias</rasd:ResourceSubType>
</Item>

NetworkSection

Not used by OpenNode templates currently.

OpenNode OVF mapped objects

OpenVZ Linux Containers

QEMU/KVM VM