Advanced features¶
Specifying the disk for deployment (root device hints)¶
The Bare Metal service supports passing hints to the deploy ramdisk about which disk it should pick for the deployment. The list of supported hints is:
model (STRING): device identifier
vendor (STRING): device vendor
serial (STRING): disk serial number
size (INT): size of the device in GiB
Note
A node’s ‘local_gb’ property is often set to a value 1 GiB less than the actual disk size to account for partitioning (this is how DevStack, TripleO and Ironic Inspector work, to name a few). However, in this case
size
should be the actual size. For example, for a 128 GiB disklocal_gb
will be 127, but size hint will be 128.wwn (STRING): unique storage identifier
wwn_with_extension (STRING): unique storage identifier with the vendor extension appended
wwn_vendor_extension (STRING): unique vendor storage identifier
rotational (BOOLEAN): whether it’s a rotational device or not. This hint makes it easier to distinguish HDDs (rotational) and SSDs (not rotational) when choosing which disk Ironic should deploy the image onto.
hctl (STRING): the SCSI address (Host, Channel, Target and Lun), e.g ‘1:0:0:0’
by_path (STRING): the alternate device name corresponding to a particular PCI or iSCSI path, e.g /dev/disk/by-path/pci-0000:00
name (STRING): the device name, e.g /dev/md0
Warning
The root device hint name should only be used for devices with constant names (e.g RAID volumes). For SATA, SCSI and IDE disk controllers this hint is not recommended because the order in which the device nodes are added in Linux is arbitrary, resulting in devices like /dev/sda and /dev/sdb switching around at boot time.
To associate one or more hints with a node, update the node’s properties
with a root_device
key, for example:
baremetal node set <node-uuid> --property root_device='{"wwn": "0x4000cca77fc4dba1"}'
That will guarantee that Bare Metal service will pick the disk device that
has the wwn
equal to the specified wwn value, or fail the deployment if it
can not be found.
Note
Starting with the Ussuri release, root device hints can be specified per-instance, see Using Bare Metal service as a standalone service.
The hints can have an operator at the beginning of the value string. If
no operator is specified the default is ==
(for numerical values)
and s==
(for string values). The supported operators are:
For numerical values:
=
equal to or greater than. This is equivalent to>=
and is supported for legacy reasons==
equal to!=
not equal to>=
greater than or equal to>
greater than<=
less than or equal to<
less than
For strings (as python comparisons):
s==
equal tos!=
not equal tos>=
greater than or equal tos>
greater thans<=
less than or equal tos<
less than<in>
substring
For collections:
<all-in>
all elements contained in collection<or>
find one of these
Examples are:
Finding a disk larger or equal to 60 GiB and non-rotational (SSD):
baremetal node set <node-uuid> --property root_device='{"size": ">= 60", "rotational": false}'
Finding a disk whose vendor is
samsung
orwinsys
:baremetal node set <node-uuid> --property root_device='{"vendor": "<or> samsung <or> winsys"}'
Note
If multiple hints are specified, a device must satisfy all the hints.
Appending kernel parameters to boot instances¶
The Bare Metal service supports passing custom kernel parameters to boot instances to fit users’ requirements. The way to append the kernel parameters is depending on how to boot instances.
Network boot¶
Currently, the Bare Metal service supports assigning unified kernel parameters to PXE booted instances by:
Modifying the
[pxe]/kernel_append_params
configuration option, for example:[pxe] kernel_append_params = quiet splash
Note
The option was called
pxe_append_params
before the Xena cycle.Copying a template from shipped templates to another place, for example:
https://opendev.org/openstack/ironic/src/branch/master/ironic/drivers/modules/pxe_config.template
Making the modifications and pointing to the custom template via the configuration options:
[pxe]/pxe_config_template
and[pxe]/uefi_pxe_config_template
.
Local boot¶
For local boot instances, users can make use of configuration drive (see Enabling the configuration drive (configdrive)) to pass a custom script to append kernel parameters when creating an instance. This is more flexible and can vary per instance. Here is an example for grub2 with ubuntu, users can customize it to fit their use case:
#!/usr/bin/env python
import os
# Default grub2 config file in Ubuntu
grub_file = '/etc/default/grub'
# Add parameters here to pass to instance.
kernel_parameters = ['quiet', 'splash']
grub_cmd = 'GRUB_CMDLINE_LINUX'
old_grub_file = grub_file+'~'
os.rename(grub_file, old_grub_file)
cmdline_existed = False
with open(grub_file, 'w') as writer, \
open(old_grub_file, 'r') as reader:
for line in reader:
key = line.split('=')[0]
if key == grub_cmd:
#If there is already some value:
if line.strip()[-1] == '"':
line = line.strip()[:-1] + ' ' + ' '.join(kernel_parameters) + '"'
cmdline_existed = True
writer.write(line)
if not cmdline_existed:
line = grub_cmd + '=' + '"' + ' '.join(kernel_parameters) + '"'
writer.write(line)
os.remove(old_grub_file)
os.system('update-grub')
os.system('reboot')
Console¶
In order to change default console configuration in the Bare Metal
service configuration file ([pxe]
section in /etc/ironic/ironic.conf
),
include the serial port terminal and serial speed. Serial speed must be
the same as the serial configuration in the BIOS settings, so that the
operating system boot process can be seen in the serial console or web console.
Following examples represent possible parameters for serial and web console
respectively.
Node serial console. The console parameter
console=ttyS0,115200n8
usesttyS0
for console output at115200bps, 8bit, non-parity
, e.g.:[pxe] # Additional append parameters for baremetal PXE boot. kernel_append_params = nofb vga=normal console=ttyS0,115200n8
For node web console configuration is similar with the addition of
ttyX
parameter, see example:[pxe] # Additional append parameters for baremetal PXE boot. kernel_append_params = nofb vga=normal console=tty0 console=ttyS0,115200n8
For detailed information on how to add consoles see the reference documents kernel params and serial console. In case of local boot the Bare Metal service is not able to control kernel boot parameters. To configure console locally, follow ‘Local boot’ section above.
Boot mode support¶
Some of the bare metal hardware types (namely, redfish
, ilo
and
generic ipmi
) support setting boot mode (Legacy BIOS or UEFI).
Note
Setting boot mode support in generic ipmi
driver is coupled
with setting boot device. That makes boot mode support in the
ipmi
driver incomplete.
Note
In this chapter we will distinguish ironic node from bare metal node. The difference is that ironic node refers to a logical node, as it is configured in ironic, while bare metal node indicates the hardware machine that ironic is managing.
The following rules apply in order when ironic manages node boot mode:
If the hardware type (or bare metal node) does not implement reading current boot mode of the bare metal node, then ironic assumes that boot mode is not set on the bare metal node
If boot mode is not set on ironic node and bare metal node boot mode is unknown (not set, can’t be read etc.), ironic node boot mode is set to the value of the [deploy]/default_boot_mode option
If boot mode is set on a bare metal node, but is not set on ironic node, bare metal node boot mode is set on ironic node
If boot mode is set on ironic node, but is not set on the bare metal node, ironic node boot mode is attempted to be set on the bare metal node (failure to set boot mode on the bare metal node will not fail ironic node deployment)
If different boot modes appear on to be set ironic node and on the bare metal node, ironic node boot mode is attempted to be set on the bare metal node (failure to set boot mode on the bare metal node will fail ironic node deployment)
Warning
If a bare metal node does not support setting boot mode, then the operator needs to make sure that boot mode configuration is consistent between ironic node and the bare metal node.
The boot modes can be configured in the Bare Metal service in the following way:
Only one boot mode (either
uefi
orbios
) can be configured for the node.If the operator wants a node to boot always in
uefi
mode orbios
mode, then they may usecapabilities
parameter withinproperties
field of an bare metal node. The operator must manually set the appropriate boot mode on the bare metal node.To configure a node in
uefi
mode, then setcapabilities
as below:openstack baremetal node set <node-uuid> --property capabilities='boot_mode:uefi'
Conversely, to configure a node in
bios
mode, then set thecapabilities
as below:openstack baremetal node set <node-uuid> --property capabilities='boot_mode:bios'
Note
The Ironic project changed the default boot mode setting for nodes from
bios
touefi
during the Yoga development cycle.
Nodes having boot_mode
set to uefi
may be requested by adding an
extra_spec
to the Compute service flavor:
openstack flavor set ironic-test-3 --property capabilities:boot_mode="uefi"
openstack server create boot --flavor ironic-test-3 --image test-image instance-1
If capabilities
is used in extra_spec
as above, nova scheduler
(ComputeCapabilitiesFilter
) will match only bare metal nodes which have
the boot_mode
set appropriately in properties/capabilities
. It will
filter out rest of the nodes.
The above facility for matching in the Compute service can be used in
heterogeneous environments where there is a mix of uefi
and bios
machines, and operator wants to provide a choice to the user regarding
boot modes. If the flavor doesn’t contain boot_mode
and boot_mode
is configured for bare metal nodes, then nova scheduler will consider all
nodes and user may get either bios
or uefi
machine.
Some hardware support setting secure boot mode, see UEFI secure boot mode for details.
Choosing the disk label¶
Note
The term disk label
is historically used in Ironic and was taken
from parted. Apparently
everyone seems to have a different word for disk label
- these
are all the same thing: disk type, partition table, partition map
and so on…
Ironic allows operators to choose which disk label they want their
bare metal node to be deployed with when Ironic is responsible for
partitioning the disk; therefore choosing the disk label does not apply
when the image being deployed is a whole disk image
.
There are some edge cases where someone may want to choose a specific disk label for the images being deployed, including but not limited to:
For machines in
bios
boot mode with disks larger than 2 terabytes it’s recommended to use agpt
disk label. That’s because a capacity beyond 2 terabytes is not addressable by using the MBR partitioning type. But, although GPT claims to be backward compatible with legacy BIOS systems that’s not always the case.Operators may want to force the partitioning to be always MBR (even if the machine is deployed with boot mode
uefi
) to avoid breakage of applications and tools running on those instances.
The disk label can be configured in two ways; when Ironic is used with the Compute service or in standalone mode. The following bullet points and sections will describe both methods:
When no disk label is provided Ironic will configure it according to the boot mode (see Boot mode support);
bios
boot mode will usemsdos
anduefi
boot mode will usegpt
.Only one disk label - either
msdos
orgpt
- can be configured for the node.
Warning
If the host is in UEFI boot mode, use of disk_label
is redundant,
and may cause deployments to fail unexpectedly if the node is not
explicitly set to boot in UEFI mode. Use of appropriate boot mode is
highly recommended.
When used with Compute service¶
When Ironic is used with the Compute service the disk label should be
set to node’s properties/capabilities
field and also to the flavor
which will request such capability, for example:
baremetal node set <node-uuid> --property capabilities='disk_label:gpt'
As for the flavor:
openstack flavor set baremetal --property capabilities:disk_label="gpt"
When used in standalone mode¶
When used without the Compute service, the disk label should be set
directly to the node’s instance_info
field, as below:
baremetal node set <node-uuid> --instance-info capabilities='{"disk_label": "gpt"}'
Notifications¶
The Bare Metal service supports the emission of notifications, which are messages sent on a message broker (like RabbitMQ or anything else supported by the oslo messaging library) that indicate various events which occur, such as when a node changes power states. These can be consumed by an external service reading from the message bus. For example, Searchlight is an OpenStack service that uses notifications to index (and make searchable) resources from the Bare Metal service.
Notifications are disabled by default. For a complete list of available notifications and instructions for how to enable them, see the Notifications.