openstack-manuals/doc/image-guide/section_ubuntu-example.xml
Stephen Gordon d0dc1ead6b Configure metadata source for cloud-init
When building Ubuntu images the metadata source to be used by
cloud-initmust be explicitly set.

Change-Id: I30e3336cf65f8c1baed358efd78d90cde1d0cc02
Closes-Bug: #1250881
backport: havana
2013-11-22 22:39:54 -05:00

219 lines
12 KiB
XML

<?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>We'll run through an example of installing an Ubuntu image. This will focus mainly on
Ubuntu 12.04 (Precise Pangolin) server. Because the Ubuntu installation process may change
across versions, if you are using a different version of Ubuntu the installer steps may
differ.</para>
<simplesect>
<title>Download an Ubuntu install ISO</title>
<para>In this example, we'll use the network installation ISO, since it's a smaller
image. The 64-bit 12.04 network installer ISO is at <link
xlink:href="http://archive.ubuntu.com/ubuntu/dists/precise/main/installer-amd64/current/images/netboot/mini.iso"
>http://archive.ubuntu.com/ubuntu/dists/precise/main/installer-amd64/current/images/netboot/mini.iso</link></para>
</simplesect>
<simplesect>
<title>Start the install process</title>
<para>Start the installation process using either <command>virt-manager</command> or
<command>virt-install</command> as described in the previous section. If using
<command>virt-install</command>, don't forget to connect your VNC client to the
virtual machine.</para>
<para>We will assume the name of your virtual machine image is
<literal>ubuntu-12.04</literal>, which we need to know when using
<command>virsh</command> commands to manipulate the state of the image.</para>
<para>If you're using virt-manager, the commands should look something like
this:<screen><prompt>#</prompt> <userinput>qemu-img create -f qcow2 /tmp/precise.qcow2 10G</userinput>
<prompt>#</prompt> <userinput>virt-install --virt-type kvm --name precise --ram 1024 \
--cdrom=/data/isos/precise-64-mini.iso \
--disk /tmp/precise.qcow2,format=qcow2 \
--network network=default \
--graphics vnc,listen=0.0.0.0 --noautoconsole \
--os-type=linux --os-variant=ubuntuprecise</userinput></screen></para>
</simplesect>
<simplesect>
<title>Step through the install</title>
<para>At the initial Installer boot menu, choose the "Install" 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
username, the default (<literal>ubuntu</literal>) 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 of 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 upon your specific use case. If your virtual machine instances will be
able to connect 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>
<para>
<note>
<para>When you hit "Continue" the virtual machine will shut down, even though it
says it will reboot.</para>
</note>
</para>
<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 precise</userinput>
<computeroutput>&lt;domain type='kvm'>
&lt;name>precise&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 instead use
the
GUI.<screen><prompt>#</prompt> <userinput>virsh start precise --paused</userinput>
<prompt>#</prompt> <userinput>virsh attach-disk --type cdrom --mode readonly precise "" hdc</userinput>
<prompt>#</prompt> <userinput>virsh resume precise</userinput></screen></para>
<note><para>In the example above, we start the instance paused, eject the disk, and then unpause. In
theory, we could have ejected the disk at the "Installation complete" 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 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> datasource:
<screen><prompt>#</prompt> <userinput>dpkg-reconfigure cloud-init</userinput></screen>
</para>
<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:<programlisting>user: admin</programlisting></para>
</simplesect>
<simplesect>
<title>Shut down the instance</title>
<para>From inside the instance, as
root:<screen><prompt>#</prompt> <userinput>/sbin/shutdown -h now</userinput></screen></para>
</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:<screen><prompt>#</prompt> <userinput>virt-sysprep -d precise</userinput></screen></para>
</simplesect>
<simplesect>
<title>Undefine the libvirt domain</title>
<para>Now that the image is ready to be uploaded to the Image service, we know 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<screen><prompt>#</prompt> <userinput>virsh undefine precise</userinput></screen></para>
</simplesect>
<simplesect>
<title>Image is complete</title>
<para>The underlying image file you created with <command>qemu-img create</command> (e.g.
<filename>/tmp/precise.qcow2</filename>) is now ready for uploading to the OpenStack
Image service.</para>
</simplesect>
</section>