deae814611
The PowerVM driver was deprecated in November 2021 as part of change Icdef0a03c3c6f56b08ec9685c6958d6917bc88cb. As noted there, all indications suggest that this driver is no longer maintained and may be abandonware. It's been some time and there's still no activity here so it's time to abandon this for real. This isn't as tied into the codebase as the old XenAPI driver was, so removal is mostly a case of deleting large swathes of code. Lovely. Change-Id: Ibf4f36136f2c65adad64f75d665c00cf2de4b400 Signed-off-by: Stephen Finucane <sfinucan@redhat.com>
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4.4 KiB
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109 lines
4.4 KiB
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=============
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Config drives
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=============
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.. note::
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This section provides deployment information about the config drive feature.
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For end-user information about the config drive feature and instance metadata
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in general, refer to the :doc:`user guide </user/metadata>`.
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Config drives are special drives that are attached to an instance when it boots.
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The instance can mount this drive and read files from it to get information that
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is normally available through :doc:`the metadata service
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</admin/metadata-service>`.
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There are many use cases for the config drive. One such use case is to pass a
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networking configuration when you do not use DHCP to assign IP addresses to
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instances. For example, you might pass the IP address configuration for the
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instance through the config drive, which the instance can mount and access
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before you configure the network settings for the instance. Another common
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reason to use config drives is load. If running something like the OpenStack
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puppet providers in your instances, they can hit the :doc:`metadata servers
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</admin/metadata-service>` every fifteen minutes, simultaneously for every
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instance you have. They are just checking in, and building facts, but it's not
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insignificant load. With a config drive, that becomes a local (cached) disk
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read. Finally, using a config drive means you're not dependent on the metadata
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service being up, reachable, or performing well to do things like reboot your
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instance that runs `cloud-init`_ at the beginning.
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Any modern guest operating system that is capable of mounting an ISO 9660 or
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VFAT file system can use the config drive.
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Requirements and guidelines
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---------------------------
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To use the config drive, you must follow the following requirements for the
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compute host and image.
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.. rubric:: Compute host requirements
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The following virt drivers support the config drive: libvirt, Hyper-V and
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VMware. The Bare Metal service also supports the config drive.
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- To use config drives with libvirt or VMware, you must first
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install the :command:`genisoimage` package on each compute host. Use the
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:oslo.config:option:`mkisofs_cmd` config option to set the path where you
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install the :command:`genisoimage` program. If :command:`genisoimage` is in
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the same path as the :program:`nova-compute` service, you do not need to set
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this flag.
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- To use config drives with Hyper-V, you must set the
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:oslo.config:option:`mkisofs_cmd` config option to the full path to an
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:command:`mkisofs.exe` installation. Additionally, you must set the
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:oslo.config:option:`hyperv.qemu_img_cmd` config option to the full path to an
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:command:`qemu-img` command installation.
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- To use config drives with the Bare Metal service, you do not need to prepare
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anything.
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.. rubric:: Image requirements
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An image built with a recent version of the `cloud-init`_ package can
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automatically access metadata passed through the config drive. The cloud-init
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package version 0.7.1 works with Ubuntu, Fedora based images (such as Red Hat
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Enterprise Linux) and openSUSE based images (such as SUSE Linux Enterprise
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Server). If an image does not have the cloud-init package installed, you must
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customize the image to run a script that mounts the config drive on boot, reads
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the data from the drive, and takes appropriate action such as adding the public
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key to an account. For more details about how data is organized on the config
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drive, refer to the :ref:`user guide <metadata-config-drive>`.
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Configuration
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-------------
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The :program:`nova-compute` service accepts the following config drive-related
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options:
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- :oslo.config:option:`api.config_drive_skip_versions`
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- :oslo.config:option:`force_config_drive`
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- :oslo.config:option:`config_drive_format`
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If using the HyperV compute driver, the following additional options are
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supported:
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- :oslo.config:option:`hyperv.config_drive_cdrom`
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For example, to ensure nova always provides a config drive to instances but
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versions ``2018-08-27`` (Rocky) and ``2017-02-22`` (Ocata) are skipped, add the
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following to :file:`nova.conf`:
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.. code-block:: ini
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[DEFAULT]
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force_config_drive = True
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[api]
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config_drive_skip_versions = 2018-08-27 2017-02-22
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.. note::
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The ``img_config_drive`` image metadata property can be used to force enable
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the config drive. In addition, users can explicitly request a config drive
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when booting instances. For more information, refer to the :ref:`user guide
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<metadata-config-drive>`.
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.. _cloud-init: https://cloudinit.readthedocs.io/en/latest/
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