117 lines
4.7 KiB
ReStructuredText
117 lines
4.7 KiB
ReStructuredText
.. _configdrive:
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Enabling the configuration drive (configdrive)
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==============================================
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Starting with the Kilo release, the Bare Metal service supports exposing
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a configuration drive image to the instances.
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The configuration drive is used to store instance-specific metadata and is present to
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the instance as a disk partition labeled ``config-2``. The configuration drive has
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a maximum size of 64MB. One use case for using the configuration drive is to
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expose a networking configuration when you do not use DHCP to assign IP
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addresses to instances.
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The configuration drive is usually used in conjunction with the Compute
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service, but the Bare Metal service also offers a standalone way of using it.
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The following sections will describe both methods.
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When used with Compute service
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------------------------------
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To enable the configuration drive for a specific request, pass
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``--config-drive true`` parameter to the ``nova boot`` command, for example::
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nova boot --config-drive true --flavor baremetal --image test-image instance-1
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It's also possible to enable the configuration drive automatically on
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all instances by configuring the ``OpenStack Compute service`` to always
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create a configuration drive by setting the following option in the
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``/etc/nova/nova.conf`` file, for example::
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[DEFAULT]
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...
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force_config_drive=True
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In some cases, you may wish to pass a user customized script when deploying an instance.
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To do this, pass ``--user-data /path/to/file`` to the ``nova boot`` command.
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More information can be found at `Provide user data to instances <http://docs.openstack.org/user-guide/cli_provide_user_data_to_instances.html>`_
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When used standalone
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--------------------
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When used without the Compute service, the operator needs to create a configuration drive
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and provide the file or HTTP URL to the Bare Metal service.
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For the format of the configuration drive, Bare Metal service expects a
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``gzipped`` and ``base64`` encoded ISO 9660 [*]_ file with a ``config-2``
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label. The
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`ironic client <http://docs.openstack.org/developer/python-ironicclient/>`_
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can generate a configuration drive in the `expected format`_. Just pass a
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directory path containing the files that will be injected into it via the
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``--config-drive`` parameter of the ``node-set-provision-state`` command,
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for example::
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ironic node-set-provision-state --config-drive /dir/configdrive_files $node_identifier active
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Accessing the configuration drive data
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--------------------------------------
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When the configuration drive is enabled, the Bare Metal service will create a partition on the
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instance disk and write the configuration drive image onto it. The
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configuration drive must be mounted before use. This is performed
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automatically by many tools, such as cloud-init and cloudbase-init. To mount
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it manually on a Linux distribution that supports accessing devices by labels,
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simply run the following::
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mkdir -p /mnt/config
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mount /dev/disk/by-label/config-2 /mnt/config
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If the guest OS doesn't support accessing devices by labels, you can use
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other tools such as ``blkid`` to identify which device corresponds to
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the configuration drive and mount it, for example::
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CONFIG_DEV=$(blkid -t LABEL="config-2" -odevice)
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mkdir -p /mnt/config
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mount $CONFIG_DEV /mnt/config
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.. [*] A config drive could also be a data block with a VFAT filesystem
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on it instead of ISO 9660. But it's unlikely that it would be needed
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since ISO 9660 is widely supported across operating systems.
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Cloud-init integration
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----------------------
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The configuration drive can be
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especially useful when used with `cloud-init
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<http://cloudinit.readthedocs.org/en/latest/topics/datasources.html#config-drive>`_,
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but in order to use it we should follow some rules:
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* ``Cloud-init`` data should be organized in the `expected format`_.
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* Since the Bare Metal service uses a disk partition as the configuration drive,
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it will only work with
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`cloud-init version >= 0.7.5 <http://bazaar.launchpad.net/~cloud-init-dev/cloud-init/trunk/view/head:/ChangeLog>`_.
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* ``Cloud-init`` has a collection of data source modules, so when
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building the image with `disk-image-builder`_ we have to define
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``DIB_CLOUD_INIT_DATASOURCES`` environment variable and set the
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appropriate sources to enable the configuration drive, for example::
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DIB_CLOUD_INIT_DATASOURCES="ConfigDrive, OpenStack" disk-image-create -o fedora-cloud-image fedora baremetal
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For more information see `how to configure cloud-init data sources
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<http://docs.openstack.org/developer/diskimage-builder/elements/cloud-init-datasources/README.html>`_.
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.. _`expected format`: http://docs.openstack.org/user-guide/cli_config_drive.html#openstack-metadata-format
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.. _disk-image-builder: http://docs.openstack.org/developer/diskimage-builder/
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