openstack-manuals/doc/image-guide/source/ubuntu-image.rst

=====================
Example: Ubuntu image
=====================

This example installs an Ubuntu 14.04 (Trusty Tahr) image.
To create an image for a different version of Ubuntu,
follow these steps with the noted differences.

Download an Ubuntu installation ISO
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Because the goal is to make the smallest possible base image,
this example uses the network installation ISO.
The Ubuntu 64-bit 14.04 network installation ISO is at the `Ubuntu download
page <http://archive.ubuntu.com/ubuntu/dists/trusty/main/installer-amd64/current/images/netboot/mini.iso>`_.

Start the installation process
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Start the installation process by using either :command:`virt-manager`
or :command:`virt-install` as described in the previous section.
If you use :command:`virt-install`, do not forget to connect
your VNC client to the virtual machine.

Assume that the name of your virtual machine image is ``ubuntu-14.04``,
which you need to know when you use :command:`virsh` commands
to manipulate the state of the image.

If you are using :command:`virt-manager`,
the commands should look something like this:

.. code-block:: console

   # qemu-img create -f qcow2 /tmp/trusty.qcow2 10G
   # virt-install --virt-type kvm --name trusty --ram 1024 \
     --cdrom=/data/isos/trusty-64-mini.iso \
     --disk /tmp/trusty.qcow2,format=qcow2 \
     --network network=default \
     --graphics vnc,listen=0.0.0.0 --noautoconsole \
     --os-type=linux --os-variant=ubuntutrusty

Step through the installation
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

At the initial Installer boot menu, choose the :guilabel:`Install` option.
Step through the installation prompts, the defaults should be fine.

.. figure:: figures/ubuntu-install.png
   :width: 100%

Hostname
~~~~~~~~

The installer may ask you to choose a host name.
The default (``ubuntu``) is fine. We will install the cloud-init
package later, which will set the host name on boot when a new
instance is provisioned using this image.

Select a mirror
~~~~~~~~~~~~~~~

The default mirror proposed by the installer should be fine.

Step through the install
~~~~~~~~~~~~~~~~~~~~~~~~

Step through the install, using the default options.
When prompted for a user name, the default (``ubuntu``) is fine.

Partition the disks
~~~~~~~~~~~~~~~~~~~

There are different options for partitioning the disks.
The default installation will use LVM partitions, and will create
three partitions (``/boot``, ``/``, swap), and this will work fine.
Alternatively, you may wish to create a single ext4 partition,
mounted to "``/``", should also work fine.

If unsure, we recommend you use the installer's default partition
scheme, since there is no clear advantage to one scheme or another.

Automatic updates
~~~~~~~~~~~~~~~~~

The Ubuntu installer will ask how you want to manage upgrades
on your system. This option depends on your specific use case.
If your virtual machine instances will be connected to the
Internet, we recommend "Install security updates automatically".

Software selection: OpenSSH server
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Choose :guilabel:`OpenSSH server` so that you will be able to SSH into
the virtual machine when it launches inside of an OpenStack cloud.

.. figure:: figures/ubuntu-software-selection.png

Install GRUB boot loader
~~~~~~~~~~~~~~~~~~~~~~~~

Select :guilabel:`Yes` when asked about installing the GRUB boot loader
to the master boot record.

.. figure:: figures/ubuntu-grub.png
   :width: 100%

For more information on configuring Grub, see the section
called ":ref:`write-to-console`".

Detach the CD-ROM and reboot
~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Select the defaults for all of the remaining options. When the
installation is complete, you will be prompted to remove the CD-ROM.

.. figure:: figures/ubuntu-finished.png
   :width: 100%

.. note::

   There is a known bug in Ubuntu 14.04; when you select ``Continue``,
   the virtual machine will shut down, even though it says it will reboot.

To eject a disk using :command:`virsh`, libvirt requires that
you attach an empty disk at the same target that the CDROM
was previously attached, which should be ``hdc``.
You can confirm the appropriate target using the
:command:`virsh dumpxml vm-image` command.

.. code-block:: console

   # virsh dumpxml trusty
   <domain type='kvm'>
     <name>trusty</name>
   ...
       <disk type='block' device='cdrom'>
       <driver name='qemu' type='raw'/>
       <target dev='hdc' bus='ide'/>
       <readonly/>
       <address type='drive' controller='0' bus='1' target='0' unit='0'/>
     </disk>
   ...
   </domain>

Run the following commands in the host as root to start up
the machine again as paused, eject the disk and resume.
If you are using ``virt-manager``, you may use the GUI instead.

.. code-block:: console

   # virsh start trusty --paused
   # virsh attach-disk --type cdrom --mode readonly trusty "" hdc
   # virsh resume trusty

.. note::

   In the previous example, you paused the instance, ejected
   the disk, and unpaused the instance. In theory, you could have
   ejected the disk at the :guilabel:`Installation complete` screen.
   However, our testing indicates that the Ubuntu installer
   locks the drive so that it cannot be ejected at that point.

Log in to newly created image
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

When you boot for the first time after install, it may ask
you about authentication tools, you can just choose :guilabel:`Exit`.
Then, log in as root using the root password you specified.

Install cloud-init
~~~~~~~~~~~~~~~~~~

The :command:`cloud-init` script starts on instance boot and
will search for a metadata provider to fetch a public key from.
The public key will be placed in the default user account for the image.

Install the ``cloud-init`` package:

.. code-block:: console

   # apt-get install cloud-init

When building Ubuntu images :command:`cloud-init` must be
explicitly configured for the metadata source in use.
The OpenStack metadata server emulates the EC2 metadata
service used by images in Amazon EC2.

To set the metadata source to be used by the image run the
:command:`dpkg-reconfigure` command against the ``cloud-init``
package. When prompted select the :guilabel:`EC2` data source:

.. code-block:: console

   # dpkg-reconfigure cloud-init

The account varies by distribution.
On Ubuntu-based virtual machines, the account is called ``ubuntu``.
On Fedora-based virtual machines, the account is called ``ec2-user``.

You can change the name of the account used by ``cloud-init``
by editing the ``/etc/cloud/cloud.cfg`` file and adding a line
with a different user. For example, to configure ``cloud-init``
to put the key in an account named ``admin``, use the following
syntax in the configuration file:

.. code-block:: console

   users:
     - name: admin
       (...)

Shut down the instance
~~~~~~~~~~~~~~~~~~~~~~

From inside the instance, as root:

.. code-block:: console

   # /sbin/shutdown -h now

Clean up (remove MAC address details)
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

The operating system records the MAC address of the virtual Ethernet
card in locations such as ``/etc/udev/rules.d/70-persistent-net.rules``
during the installation process. However, each time the image boots up,
the virtual Ethernet card will have a different MAC address,
so this information must be deleted from the configuration file.

There is a utility called :command:`virt-sysprep`, that performs
various cleanup tasks such as removing the MAC address references.
It will clean up a virtual machine image in place:

.. code-block:: console

   # virt-sysprep -d trusty

Undefine the libvirt domain
~~~~~~~~~~~~~~~~~~~~~~~~~~~

Now that the image is ready to be uploaded to the Image service,
you no longer need to have this virtual machine image managed by libvirt.
Use the :command:`virsh undefine vm-image` command to inform libvirt:

.. code-block:: console

   # virsh undefine trusty

Image is complete
~~~~~~~~~~~~~~~~~

The underlying image file that you created with the
:command:`qemu-img create` command, such as ``/tmp/trusty.qcow2``,
is now ready for uploading to the Image service by using the
:command:`openstack image create` command. For more information,
see the `Glance User Guide <https://docs.openstack.org/glance/latest/user/index.html>`__.