cc17246d2b
Adds some text on the general instruction on how to build user-image by virtual machine software. See also: https://review.opendev.org/#/c/710966/ Change-Id: Ic84bc14ff0bce609009455c644a1601f990a7b45
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3.6 KiB
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100 lines
3.6 KiB
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Create user images for the Bare Metal service
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~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
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Bare Metal provisioning requires two sets of images: the deploy images
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and the user images. The :ref:`deploy images <deploy-ramdisk>` are used by the
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Bare Metal service to prepare the bare metal server for actual OS deployment.
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Whereas the user images are installed on the bare metal server to be used by
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the end user. There are two types of user images:
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*partition images*
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contain only the contents of the root partition. Additionally, two more
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images are used together with them: an image with a kernel and with
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an initramfs.
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.. warning::
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To use partition images with local boot, Grub2 must be installed on
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them.
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*whole disk images*
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contain a complete partition table with one or more partitions.
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.. warning::
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The kernel/initramfs pair must not be used with whole disk images,
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otherwise they'll be mistaken for partition images.
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Building user images
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^^^^^^^^^^^^^^^^^^^^
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disk-image-builder
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------------------
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The `disk-image-builder`_ can be used to create user images required for
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deployment and the actual OS which the user is going to run.
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- Install diskimage-builder package (use virtualenv, if you don't
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want to install anything globally):
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.. code-block:: console
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# pip install diskimage-builder
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- Build the image your users will run (Ubuntu image has been taken as
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an example):
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- Partition images
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.. code-block:: console
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$ disk-image-create ubuntu baremetal dhcp-all-interfaces grub2 -o my-image
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- Whole disk images
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.. code-block:: console
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$ disk-image-create ubuntu vm dhcp-all-interfaces -o my-image
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The partition image command creates ``my-image.qcow2``,
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``my-image.vmlinuz`` and ``my-image.initrd`` files. The ``grub2`` element
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in the partition image creation command is only needed if local boot will
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be used to deploy ``my-image.qcow2``, otherwise the images
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``my-image.vmlinuz`` and ``my-image.initrd`` will be used for PXE booting
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after deploying the bare metal with ``my-image.qcow2``. For whole disk images
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only the main image is used.
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If you want to use Fedora image, replace ``ubuntu`` with ``fedora`` in the
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chosen command.
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.. _disk-image-builder: https://docs.openstack.org/diskimage-builder/latest/
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Virtual machine
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---------------
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Virtual machine software can also be used to build user images. There are
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different software options available, qemu-kvm is usually a good choice on
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linux platform, it supports emulating many devices and even building images
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for architectures other than the host machine by software emulation.
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VirtualBox is another good choice for non-linux host.
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The procedure varies depending on the software used, but the steps for
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building an image are similar, the user creates a virtual machine, and
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installs the target system just like what is done for a real hardware. The
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system can be highly customized like partition layout, drivers or software
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shipped, etc.
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Usually libvirt and its management tools are used to make interaction with
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qemu-kvm easier, for example, to create a virtual machine with
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``virt-install``::
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$ virt-install --name centos8 --ram 4096 --vcpus=2 -f centos8.qcow2 \
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> --cdrom CentOS-8-x86_64-1905-dvd1.iso
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Graphic frontend like ``virt-manager`` can also be utilized.
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The disk file can be used as user image after the system is set up and powered
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off. The path of the disk file varies depending on the software used, usually
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it's stored in a user-selected part of the local file system. For qemu-kvm or
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GUI frontend building upon it, it's typically stored at
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``/var/lib/libvirt/images``.
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