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8.2 KiB
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258 lines
8.2 KiB
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=====================
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Example: Ubuntu image
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=====================
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This example installs an Ubuntu 14.04 (Trusty Tahr) image.
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To create an image for a different version of Ubuntu,
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follow these steps with the noted differences.
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Download an Ubuntu installation ISO
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~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
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Because the goal is to make the smallest possible base image,
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this example uses the network installation ISO.
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The Ubuntu 64-bit 14.04 network installation ISO is at the `Ubuntu download
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page <http://archive.ubuntu.com/ubuntu/dists/trusty/main/installer-amd64/current/images/netboot/mini.iso>`_.
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Start the installation process
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~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
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Start the installation process by using either :command:`virt-manager`
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or :command:`virt-install` as described in the previous section.
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If you use :command:`virt-install`, do not forget to connect
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your VNC client to the virtual machine.
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Assume that the name of your virtual machine image is ``ubuntu-14.04``,
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which you need to know when you use :command:`virsh` commands
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to manipulate the state of the image.
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If you are using :command:`virt-manager`,
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the commands should look something like this:
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.. code-block:: console
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# qemu-img create -f qcow2 /tmp/trusty.qcow2 10G
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# virt-install --virt-type kvm --name trusty --ram 1024 \
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--cdrom=/data/isos/trusty-64-mini.iso \
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--disk /tmp/trusty.qcow2,format=qcow2 \
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--network network=default \
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--graphics vnc,listen=0.0.0.0 --noautoconsole \
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--os-type=linux --os-variant=ubuntutrusty
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Step through the installation
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~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
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At the initial Installer boot menu, choose the :guilabel:`Install` option.
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Step through the installation prompts, the defaults should be fine.
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.. figure:: figures/ubuntu-install.png
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:width: 100%
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Hostname
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~~~~~~~~
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The installer may ask you to choose a host name.
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The default (``ubuntu``) is fine. We will install the cloud-init
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package later, which will set the host name on boot when a new
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instance is provisioned using this image.
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Select a mirror
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~~~~~~~~~~~~~~~
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The default mirror proposed by the installer should be fine.
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Step through the install
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~~~~~~~~~~~~~~~~~~~~~~~~
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Step through the install, using the default options.
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When prompted for a user name, the default (``ubuntu``) is fine.
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Partition the disks
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~~~~~~~~~~~~~~~~~~~
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There are different options for partitioning the disks.
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The default installation will use LVM partitions, and will create
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three partitions (``/boot``, ``/``, swap), and this will work fine.
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Alternatively, you may wish to create a single ext4 partition,
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mounted to "``/``", should also work fine.
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If unsure, we recommend you use the installer's default partition
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scheme, since there is no clear advantage to one scheme or another.
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Automatic updates
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~~~~~~~~~~~~~~~~~
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The Ubuntu installer will ask how you want to manage upgrades
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on your system. This option depends on your specific use case.
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If your virtual machine instances will be connected to the
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Internet, we recommend "Install security updates automatically".
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Software selection: OpenSSH server
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~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
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Choose :guilabel:`OpenSSH server` so that you will be able to SSH into
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the virtual machine when it launches inside of an OpenStack cloud.
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.. figure:: figures/ubuntu-software-selection.png
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Install GRUB boot loader
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~~~~~~~~~~~~~~~~~~~~~~~~
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Select :guilabel:`Yes` when asked about installing the GRUB boot loader
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to the master boot record.
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.. figure:: figures/ubuntu-grub.png
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:width: 100%
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For more information on configuring Grub, see the section
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called ":ref:`write-to-console`".
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Detach the CD-ROM and reboot
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~~~~~~~~~~~~~~~~~~~~~~~~~~~~
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Select the defaults for all of the remaining options. When the
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installation is complete, you will be prompted to remove the CD-ROM.
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.. figure:: figures/ubuntu-finished.png
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:width: 100%
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.. note::
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There is a known bug in Ubuntu 14.04; when you select ``Continue``,
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the virtual machine will shut down, even though it says it will reboot.
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To eject a disk using :command:`virsh`, libvirt requires that
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you attach an empty disk at the same target that the CDROM
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was previously attached, which should be ``hdc``.
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You can confirm the appropriate target using the
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:command:`virsh dumpxml vm-image` command.
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.. code-block:: console
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# virsh dumpxml trusty
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<domain type='kvm'>
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<name>trusty</name>
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...
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<disk type='block' device='cdrom'>
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<driver name='qemu' type='raw'/>
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<target dev='hdc' bus='ide'/>
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<readonly/>
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<address type='drive' controller='0' bus='1' target='0' unit='0'/>
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</disk>
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...
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</domain>
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Run the following commands in the host as root to start up
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the machine again as paused, eject the disk and resume.
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If you are using ``virt-manager``, you may use the GUI instead.
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.. code-block:: console
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# virsh start trusty --paused
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# virsh attach-disk --type cdrom --mode readonly trusty "" hdc
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# virsh resume trusty
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.. note::
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In the previous example, you paused the instance, ejected
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the disk, and unpaused the instance. In theory, you could have
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ejected the disk at the :guilabel:`Installation complete` screen.
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However, our testing indicates that the Ubuntu installer
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locks the drive so that it cannot be ejected at that point.
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Log in to newly created image
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~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
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When you boot for the first time after install, it may ask
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you about authentication tools, you can just choose :guilabel:`Exit`.
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Then, log in as root using the root password you specified.
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Install cloud-init
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~~~~~~~~~~~~~~~~~~
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The :command:`cloud-init` script starts on instance boot and
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will search for a metadata provider to fetch a public key from.
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The public key will be placed in the default user account for the image.
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Install the ``cloud-init`` package:
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.. code-block:: console
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# apt-get install cloud-init
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When building Ubuntu images :command:`cloud-init` must be
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explicitly configured for the metadata source in use.
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The OpenStack metadata server emulates the EC2 metadata
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service used by images in Amazon EC2.
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To set the metadata source to be used by the image run the
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:command:`dpkg-reconfigure` command against the ``cloud-init``
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package. When prompted select the :guilabel:`EC2` data source:
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.. code-block:: console
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# dpkg-reconfigure cloud-init
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The account varies by distribution.
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On Ubuntu-based virtual machines, the account is called ``ubuntu``.
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On Fedora-based virtual machines, the account is called ``ec2-user``.
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You can change the name of the account used by ``cloud-init``
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by editing the ``/etc/cloud/cloud.cfg`` file and adding a line
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with a different user. For example, to configure ``cloud-init``
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to put the key in an account named ``admin``, use the following
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syntax in the configuration file:
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.. code-block:: console
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users:
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- name: admin
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(...)
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Shut down the instance
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~~~~~~~~~~~~~~~~~~~~~~
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From inside the instance, as root:
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.. code-block:: console
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# /sbin/shutdown -h now
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Clean up (remove MAC address details)
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~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
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The operating system records the MAC address of the virtual Ethernet
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card in locations such as ``/etc/udev/rules.d/70-persistent-net.rules``
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during the installation process. However, each time the image boots up,
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the virtual Ethernet card will have a different MAC address,
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so this information must be deleted from the configuration file.
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There is a utility called :command:`virt-sysprep`, that performs
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various cleanup tasks such as removing the MAC address references.
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It will clean up a virtual machine image in place:
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.. code-block:: console
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# virt-sysprep -d trusty
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Undefine the libvirt domain
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~~~~~~~~~~~~~~~~~~~~~~~~~~~
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Now that the image is ready to be uploaded to the Image service,
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you no longer need to have this virtual machine image managed by libvirt.
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Use the :command:`virsh undefine vm-image` command to inform libvirt:
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.. code-block:: console
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# virsh undefine trusty
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Image is complete
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~~~~~~~~~~~~~~~~~
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The underlying image file that you created with the
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:command:`qemu-img create` command, such as ``/tmp/trusty.qcow2``,
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is now ready for uploading to the Image service by using the
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:command:`openstack image create` command. For more information, see the
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`Create or update an image
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<https://docs.openstack.org/user-guide/common/cli-manage-images.html#create-or-update-an-image-glance>`__.
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