You can set image properties that can be consumed by other services to affect the behavior of those other services. For example:
Some important points to keep in mind:
In order to allow custom image properties, Glance must be configured with
the glance-api.conf
setting allow_additional_image_properties
set
to True. (This is the default setting.)
The glance-api.conf
setting image_property_quota
should be
sufficiently high to allow any additional desired properties. (The default
is 128.)
You can use Glance property protections to control access to specific image properties, should that be desirable. See the Property Protections section of this Guide for more information.
You can use a plugin to the interoperable image import process to set specific properties on non-admin images imported into Glance. See Customizing the image import process for more information. See the original spec, Inject metadata properties automatically to non-admin images for a discussion of the use case addressed by this plugin.
The Nova ImagePropertiesFilter, enabled by default in the Compute Service, consumes image properties to determine proper scheduling of builds to compute hosts. See the Compute schedulers section of the Nova Configuration Guide for more information.
Nova has a setting, non_inheritable_image_properties
, that allows you
to specify which image properties from the image a virtual machine
was booted from will not be propagated to a snapshot image of that
virtual machine. See the Configuration Options
section of the Nova Configuration Guide for more information.
In a mixed hypervisor environment, the Compute Service uses the
hypervisor_type
image property to match images to the correct hypervisor
type.
Depending upon what hypervisors are in use in your Nova installation, there may be other image properties that these hypervisors can consume to affect their behavior. Read through the configuration information for your hypervisors in the Hypervisors section of the Nova Configuration Guide for more information.
In particular, the VMware hypervisor driver requires that particular image properties be set for optimal functioning. See the VMware vSphere section of the Nova Configuration Guide for more information.
Here is a list of useful image properties and the values they expect.
Specific to | Key | Description | Supported values |
---|---|---|---|
All | architecture |
The CPU architecture that must be supported by the hypervisor. For
example, x86_64 , arm , or ppc64 . Run uname -m
to get the architecture of a machine. We strongly recommend using
the architecture data vocabulary defined by the libosinfo project for this purpose. |
|
All | hypervisor_type |
The hypervisor type. Note that qemu is used for both QEMU and KVM
hypervisor types. |
hyperv , ironic , lxc , qemu , uml , vmware , or
xen . |
All | instance_type_rxtx_factor |
Optional property allows created servers to have a different bandwidth
cap than that defined in the network they are attached to. This factor
is multiplied by the rxtx_base property of the network. The
rxtx_base property defaults to 1.0 , which is the same as the
attached network. This parameter is only available for Xen or NSX based
systems. |
Float (default value is 1.0 ) |
All | instance_uuid |
For snapshot images, this is the UUID of the server used to create this image. | Valid server UUID |
All | img_config_drive |
Specifies whether the image needs a config drive. | mandatory or optional (default if property is not used). |
All | kernel_id |
The ID of an image stored in the Image service that should be used as the kernel when booting an AMI-style image. | Valid image ID |
All | os_distro |
The common name of the operating system distribution in lowercase (uses the same data vocabulary as the libosinfo project). Specify only a recognized value for this field. Deprecated values are listed to assist you in searching for the recognized value. |
|
All | os_version |
The operating system version as specified by the distributor. | Valid version number (for example, 11.10 ). |
All | os_secure_boot |
Secure Boot is a security standard. When the instance starts, Secure Boot first examines software such as firmware and OS by their signature and only allows them to run if the signatures are valid. For Hyper-V: Images must be prepared as Generation 2 VMs. Instance must
also contain |
|
All | ramdisk_id |
The ID of image stored in the Image service that should be used as the ramdisk when booting an AMI-style image. | Valid image ID. |
All | trait:<trait_name> |
Added in the Rocky release. Functionality is similar to traits specified in flavor extra specs. Traits allow specifying a server to build on a compute node with the set of traits specified in the image. The traits are associated with the resource provider that represents the compute node in the Placement API. The syntax of specifying traits is trait:<trait_name>=value, for example:
The nova scheduler will pass required traits specified on the image to the Placement API to include only resource providers that can satisfy the required traits. Traits for the resource providers can be managed using the osc-placement plugin. Image traits are used by the nova scheduler even in cases of volume backed instances, if the volume source is an image with traits. |
Only valid value is
|
All | vm_mode |
The virtual machine mode. This represents the host/guest ABI (application binary interface) used for the virtual machine. |
|
libvirt API driver | hw_cpu_sockets |
The preferred number of sockets to expose to the guest. | Integer. |
libvirt API driver | hw_cpu_cores |
The preferred number of cores to expose to the guest. | Integer. |
libvirt API driver | hw_cpu_threads |
The preferred number of threads to expose to the guest. | Integer. |
libvirt API driver | hw_cpu_policy |
Used to pin the virtual CPUs (vCPUs) of instances to the host’s physical CPU cores (pCPUs). Host aggregates should be used to separate these pinned instances from unpinned instances as the latter will not respect the resourcing requirements of the former. |
|
libvirt API driver | hw_cpu_thread_policy |
Further refine hw_cpu_policy=dedicated by stating how hardware CPU
threads in a simultaneous multithreading-based (SMT) architecture be
used. SMT-based architectures include Intel processors with
Hyper-Threading technology. In these architectures, processor cores
share a number of components with one or more other cores. Cores in
such architectures are commonly referred to as hardware threads, while
the cores that a given core share components with are known as thread
siblings. |
|
libvirt API driver | hw_disk_bus |
Specifies the type of disk controller to attach disk devices to. | One of scsi , virtio , uml , xen , ide , or usb . |
libvirt API driver | hw_pointer_model |
Input devices that allow interaction with a graphical framebuffer, for example to provide a graphic tablet for absolute cursor movement. Currently only supported by the KVM/QEMU hypervisor configuration and VNC or SPICE consoles must be enabled. | usbtablet |
libvirt API driver | hw_rng_model |
Adds a random-number generator device to the image’s instances. The cloud administrator can enable and control device behavior by configuring the instance’s flavor. By default:
rng_dev_path=/dev/hwrng
|
virtio , or other supported device. |
libvirt API driver | hw_time_hpet |
Adds support for the High Precision Event Timer (HPET) for x86 guests
in the libvirt driver when hypervisor_type=qemu and
architecture=i686 or architecture=x86_64 . The timer can be
enabled by setting hw_time_hpet=true . By default HPET remains
disabled. |
true or false (default) |
libvirt API driver, Hyper-V driver | hw_machine_type |
For libvirt: Enables booting an ARM system using the specified machine
type. By default, if an ARM image is used and its type is not specified,
Compute uses For Hyper-V: Specifies whether the Hyper-V instance will be a generation 1 or generation 2 VM. By default, if the property is not provided, the instances will be generation 1 VMs. If the image is specific for generation 2 VMs but the property is not provided accordingly, the instance will fail to boot. |
For libvirt: Valid types can be viewed by using the
virsh capabilities command (machine types are displayed in
the For hyper-V: Acceptable values are either |
libvirt API driver, XenAPI driver | os_type |
The operating system installed on the image. The libvirt API driver
and XenAPI driver contains logic that takes different actions
depending on the value of the os_type parameter of the image.
For example, for os_type=windows images, it creates a FAT32-based
swap partition instead of a Linux swap partition, and it limits the
injected host name to less than 16 characters. |
linux or windows . |
libvirt API driver | hw_scsi_model |
Enables the use of VirtIO SCSI (virtio-scsi ) to provide block
device access for compute instances; by default, instances use VirtIO
Block (virtio-blk ). VirtIO SCSI is a para-virtualized SCSI
controller device that provides improved scalability and performance,
and supports advanced SCSI hardware. |
virtio-scsi |
libvirt API driver | hw_serial_port_count |
Specifies the count of serial ports that should be provided. If
hw:serial_port_count is not set in the flavor’s extra_specs, then
any count is permitted. If hw:serial_port_count is set, then this
provides the default serial port count. It is permitted to override the
default serial port count, but only with a lower value. |
Integer |
libvirt API driver | hw_video_model |
The video image driver used. | vga , cirrus , vmvga , xen , or qxl . |
libvirt API driver | hw_video_ram |
Maximum RAM for the video image. Used only if a hw_video:ram_max_mb
value has been set in the flavor’s extra_specs and that value is higher
than the value set in hw_video_ram . |
Integer in MB (for example, 64 ). |
libvirt API driver | hw_watchdog_action |
Enables a virtual hardware watchdog device that carries out the
specified action if the server hangs. The watchdog uses the
i6300esb device (emulating a PCI Intel 6300ESB). If
hw_watchdog_action is not specified, the watchdog is disabled. |
|
libvirt API driver | os_command_line |
The kernel command line to be used by the libvirt driver, instead
of the default. For Linux Containers (LXC), the value is used as
arguments for initialization. This key is valid only for Amazon kernel,
ramdisk , or machine images (aki , ari , or ami ). |
|
libvirt API driver and VMware API driver | hw_vif_model |
Specifies the model of virtual network interface device to use. |
|
libvirt API driver | hw_vif_multiqueue_enabled |
If true , this enables the virtio-net multiqueue feature. In
this case, the driver sets the number of queues equal to the number
of guest vCPUs. This makes the network performance scale across a
number of vCPUs. |
true | false |
libvirt API driver | hw_boot_menu |
If true , enables the BIOS bootmenu. In cases where both the image
metadata and Extra Spec are set, the Extra Spec setting is used. This
allows for flexibility in setting/overriding the default behavior as
needed. |
true or false |
libvirt API driver | img_hide_hypervisor_id |
Some hypervisors add a signature to their guests. While the presence
of the signature can enable some paravirtualization features on the
guest, it can also have the effect of preventing some drivers from
loading. Hiding the signature by setting this property to true
may allow such drivers to load and work. |
true or false |
VMware API driver | vmware_adaptertype |
The virtual SCSI or IDE controller used by the hypervisor. | lsiLogic , lsiLogicsas , busLogic , ide , or
paraVirtual . |
VMware API driver | vmware_ostype |
A VMware GuestID which describes the operating system installed in
the image. This value is passed to the hypervisor when creating a
virtual machine. If not specified, the key defaults to otherGuest . |
See thinkvirt.com. |
VMware API driver | vmware_image_version |
Currently unused. | 1 |
XenAPI driver | auto_disk_config |
If true , the root partition on the disk is automatically resized
before the instance boots. This value is only taken into account by
the Compute service when using a Xen-based hypervisor with the
XenAPI driver. The Compute service will only attempt to resize if
there is a single partition on the image, and only if the partition
is in ext3 or ext4 format. |
true or false |
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