147 lines
5.2 KiB
ReStructuredText
147 lines
5.2 KiB
ReStructuredText
.. _configdrive:
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Enabling the configuration drive (configdrive)
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==============================================
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The Bare Metal service supports exposing a configuration drive image to
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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 :command:`nova boot` command, for example::
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openstack server create --use-config-drive --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 :command:`nova boot` command.
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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
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configuration drive and provide the file or HTTP URL to the Bare Metal service.
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See :ref:`deploy-configdrive` for details.
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Configuration drive storage in an object store
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----------------------------------------------
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Under normal circumstances, the configuration drive can be stored in the
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Bare Metal service when the size is less than 64KB. Optionally, if the size
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is larger than 64KB there is support to store it in a swift endpoint. Both
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swift and radosgw use swift-style APIs.
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The following option in ``/etc/ironic/ironic.conf`` enables swift as an object
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store backend to store config drive. This uses the Identity service to
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establish a session between the Bare Metal service and the
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Object Storage service. ::
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[deploy]
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...
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configdrive_use_object_store = True
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Use the following options in ``/etc/ironic/ironic.conf`` to enable radosgw.
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Credentials in the swift section are needed because radosgw will not use the
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Identity service and relies on radosgw's username and password authentication
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instead. ::
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[deploy]
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...
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configdrive_use_object_store = True
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[swift]
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...
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username = USERNAME
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password = PASSWORD
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auth_url = http://RADOSGW_IP:8000/auth/v1
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If the :ref:`direct-deploy` is being used, edit ``/etc/glance/glance-api.conf``
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to store the instance images in respective object store (radosgw or swift)
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as well::
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[glance_store]
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...
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swift_store_user = USERNAME
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swift_store_key = PASSWORD
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swift_store_auth_address = http://RADOSGW_OR_SWIFT_IP:PORT/auth/v1
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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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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.io/en/latest/topics/datasources/configdrive.html>`_,
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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 <https://github.com/cloud-init/cloud-init/blob/2d6e4219db73e80c135efd83753f9302f778f08d/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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<https://docs.openstack.org/diskimage-builder/latest/elements/cloud-init-datasources/README.html>`_.
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.. _`expected format`: https://docs.openstack.org/nova/latest/user/vendordata.html
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.. _disk-image-builder: https://docs.openstack.org/diskimage-builder/latest/
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