openstack-manuals/doc/image-guide/section_ubuntu-example.xml

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<?xml version="1.0" encoding="UTF-8"?>
<section xmlns="http://docbook.org/ns/docbook"
xmlns:xi="http://www.w3.org/2001/XInclude"
xmlns:xlink="http://www.w3.org/1999/xlink"
version="5.0"
xml:id="ubuntu-image">
<title>Example: Ubuntu image</title>
<para>This example installs a Ubuntu 14.04 (Trusty Tahr) image. To create an image for a
different version of Ubuntu, follow these steps with the noted differences.</para>
<simplesect>
<title>Download an Ubuntu install ISO</title>
<para>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 installer ISO is at <link
xlink:href="http://archive.ubuntu.com/ubuntu/dists/trusty/main/installer-amd64/current/images/netboot/mini.iso"
>http://archive.ubuntu.com/ubuntu/dists/trusty/main/installer-amd64/current/images/netboot/mini.iso</link>.</para>
</simplesect>
<simplesect>
<title>Start the install process</title>
<para>Start the installation process by using either <command>virt-manager</command> or
<command>virt-install</command> as described in the previous section. If you use
<command>virt-install</command>, do not forget to connect your VNC client to the
virtual machine.</para>
<para>Assume that the name of your virtual machine image is <literal>ubuntu-14.04</literal>,
which you need to know when you use <command>virsh</command> commands to manipulate the
state of the image.</para>
<para>If you are using <command>virt-manager</command>, the commands should look something
like this:</para>
<screen><prompt>#</prompt> <userinput>qemu-img create -f qcow2 /tmp/trusty.qcow2 10G</userinput>
<prompt>#</prompt> <userinput>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</userinput></screen>
</simplesect>
<simplesect>
<title>Step through the install</title>
<para>At the initial Installer boot menu, choose the <guilabel>Install</guilabel> option.
Step through the install prompts, the defaults should be fine.</para>
<mediaobject>
<imageobject>
<imagedata fileref="figures/ubuntu-install.png" format="PNG" contentwidth="6in"/>
</imageobject>
</mediaobject>
</simplesect>
<simplesect>
<title>Hostname</title>
<para>The installer may ask you to choose a hostname. The default
(<literal>ubuntu</literal>) is fine. We will install the cloud-init package later, which
will set the hostname on boot when a new instance is provisioned using this
image.</para>
</simplesect>
<simplesect>
<title>Select a mirror</title>
<para>The default mirror proposed by the installer should be fine.</para>
</simplesect>
<simplesect>
<title>Step through the install</title>
<para>Step through the install, using the default options. When prompted for a user name,
the default (<systemitem class="username">ubuntu</systemitem>) is fine.</para>
</simplesect>
<simplesect>
<title>Partition the disks</title>
<para>There are different options for partitioning the disks. The default installation will
use LVM partitions, and will create three partitions (<filename>/boot</filename>,
<filename>/</filename>, swap), and this will work fine. Alternatively, you may wish
to create a single ext4 partition, mounted to "<literal>/</literal>", should also work
fine.</para>
<para>If unsure, we recommend you use the installer's default partition scheme, since there
is no clear advantage to one scheme or another.</para>
</simplesect>
<simplesect>
<title>Automatic updates</title>
<para>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".</para>
</simplesect>
<simplesect>
<title>Software selection: OpenSSH server</title>
<para>Choose "OpenSSH server"so that you will be able to SSH into the virtual machine when
it launches inside of an OpenStack cloud.</para>
<mediaobject>
<imageobject>
<imagedata fileref="figures/ubuntu-software-selection.png" format="PNG"
contentwidth="6in"/>
</imageobject>
</mediaobject>
</simplesect>
<simplesect>
<title>Install GRUB boot loader</title>
<para>Select "Yes" when asked about installing the GRUB boot loader to the master boot
record.</para>
<mediaobject>
<imageobject>
<imagedata fileref="figures/ubuntu-grub.png" format="PNG" contentwidth="6in"/>
</imageobject>
</mediaobject>
</simplesect>
<simplesect>
<title>Detach the CD-ROM and reboot</title>
<para>Select the defaults for all of the remaining options. When the installation is
complete, you will be prompted to remove the CD-ROM.</para>
<mediaobject>
<imageobject>
<imagedata fileref="figures/ubuntu-finished.png" format="PNG" contentwidth="6in"/>
</imageobject>
</mediaobject>
<note>
<para>When you hit "Continue" the virtual machine will shut down, even though it says it
will reboot.</para>
</note>
<para>To eject a disk using <command>virsh</command>, libvirt requires that you attach an
empty disk at the same target that the CDROM was previously attached, which should be
<literal>hdc</literal>. You can confirm the appropriate target using the
<command>dom dumpxml <replaceable>vm-image</replaceable></command> command.</para>
<screen><prompt>#</prompt> <userinput>virsh dumpxml trusty</userinput>
<computeroutput>&lt;domain type='kvm'>
&lt;name>trusty&lt;/name>
...
&lt;disk type='block' device='cdrom'>
&lt;driver name='qemu' type='raw'/>
&lt;target dev='hdc' bus='ide'/>
&lt;readonly/>
&lt;address type='drive' controller='0' bus='1' target='0' unit='0'/>
&lt;/disk>
...
&lt;/domain>
</computeroutput></screen>
<para>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.</para>
<screen><prompt>#</prompt> <userinput>virsh start trusty --paused</userinput>
<prompt>#</prompt> <userinput>virsh attach-disk --type cdrom --mode readonly trusty "" hdc</userinput>
<prompt>#</prompt> <userinput>virsh resume trusty</userinput></screen>
<note>
<para>In the previous example, you paused the instance paused, ejected the disk, and
unpaused the instance. In theory, you could have ejected the disk at the
<guilabel>Installation complete</guilabel> screen. However, our testing
indicates that the Ubuntu installer locks the drive so that it cannot be ejected at
that point.</para>
</note>
</simplesect>
<simplesect>
<title>Log in to newly created image</title>
<para>When you boot for the first time after install, it may ask you about authentication
tools, you can just choose 'Exit'. Then, log in as root using the root password you
specified.</para>
</simplesect>
<simplesect>
<title>Install cloud-init</title>
<para>The <command>cloud-init</command> 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.</para>
<para>Install the <package>cloud-init</package> package:</para>
<screen><prompt>#</prompt> <userinput>apt-get install cloud-init</userinput></screen>
<para>When building Ubuntu images <command>cloud-init</command> 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.</para>
<para>To set the metadata source to be used by the image run the
<command>dpkg-reconfigure</command> command against the
<package>cloud-init</package> package. When prompted select the
<literal>EC2</literal> data source:</para>
<screen><prompt>#</prompt> <userinput>dpkg-reconfigure cloud-init</userinput></screen>
<para>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".</para>
<para>You can change the name of the account used by cloud-init by editing the
<filename>/etc/cloud/cloud.cfg</filename> file and adding a line with a different
user. For example, to configure cloud-init to put the key in an account named "admin",
edit the config file so it has the line:</para>
<programlisting>user: admin</programlisting>
</simplesect>
<simplesect>
<title>Shut down the instance</title>
<para>From inside the instance, as root:</para>
<screen><prompt>#</prompt> <userinput>/sbin/shutdown -h now</userinput></screen>
</simplesect>
<simplesect>
<title>Clean up (remove MAC address details)</title>
<para>The operating system records the MAC address of the virtual Ethernet card in locations
such as <filename>/etc/udev/rules.d/70-persistent-net.rules</filename> during the
instance 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.</para>
<para>There is a utility called <command>virt-sysprep</command>, that performs various
cleanup tasks such as removing the MAC address references. It will clean up a virtual
machine image in place:</para>
<screen><prompt>#</prompt> <userinput>virt-sysprep -d trusty</userinput></screen>
</simplesect>
<simplesect>
<title>Undefine the libvirt domain</title>
<para>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
<replaceable>vm-image</replaceable></command> command to inform libvirt:</para>
<screen><prompt>#</prompt> <userinput>virsh undefine trusty</userinput></screen>
</simplesect>
<simplesect>
<title>Image is complete</title>
<para>The underlying image file that you created with <command>qemu-img create</command>,
such as <filename>/tmp/trusty.qcow2</filename>, is now ready for uploading to the
OpenStack Image Service.</para>
</simplesect>
</section>