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Example: Fedora image

This example shows you how to install a Fedora image and focuses mainly on Fedora 25. Because the Fedora installation process might differ across versions, the installation steps might differ if you use a different version of Fedora.

Download a Fedora install ISO

Visit the Fedora download site.
Navigate to the Download Fedora Server page for a Fedora Server ISO image.
Choose the ISO image you want to download.

For example, the Netinstall Image is a good choice because it is a smaller image that downloads missing packages from the Internet during installation.

Start the installation process

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

Assume that:

The name of your virtual machine image is fedora; you need this name when you use virsh commands to manipulate the state of the image.
You saved the netinstall ISO image to the /tmp directory.

If you use the virt-install command, the commands should look something like this:

# qemu-img create -f qcow2 /tmp/fedora.qcow2 10G
# virt-install --virt-type kvm --name fedora --ram 1024 \
  --disk /tmp/fedora.qcow2,format=qcow2 \
  --network network=default \
  --graphics vnc,listen=0.0.0.0 --noautoconsole \
  --os-type=linux --os-variant=fedora23 \
  --location=/tmp/Fedora-Server-netinst-x86_64-25-1.3.iso

Step through the installation

After the installation program starts, choose your preferred language and click Continue to get to the installation summary. Accept the defaults.

Review the Ethernet status

Ensure that the Ethernet setting is ON. Additionally, make sure that IPv4 Settings' Method is Automatic (DHCP), which is the default.

Hostname

The installer allows you to choose a host name. The default (localhost.localdomain) is fine. You install the cloud-init package later, which sets the host name on boot when a new instance is provisioned using this image.

Partition the disks

There are different options for partitioning the disks. The default installation uses LVM partitions, and creates three partitions (/boot, /, swap), which works fine. Alternatively, you might want to create a single ext4 partition that is mounted to /, which also works fine.

If unsure, use the default partition scheme for the installer. While no scheme is inherently better than another, having the partition that you want to dynamically grow at the end of the list will allow it to grow without crossing another partition's boundary.

Select software to install

Step through the installation, using the default options. The simplest thing to do is to choose the Minimal Install install, which installs an SSH server.

Set the root password

During the installation, remember to set the root password when prompted.

Detach the CD-ROM and reboot

Wait until the installation is complete.

To eject a disk by using the virsh command, libvirt requires that you attach an empty disk at the same target that the CD-ROM was previously attached, which may be hda. You can confirm the appropriate target using the virsh dumpxml vm-image command.

# virsh dumpxml fedora
<domain type='kvm' id='30'>
  <name>fedora</name>
...
    <disk type='file' device='cdrom'>
      <driver name='qemu' type='raw'/>
      <source file='/tmp/Fedora-Server-netinst-x86_64-25-1.3.iso'/>
      <backingStore/>
      <target dev='hda' bus='ide'/>
      <readonly/>
      <alias name='ide0-0-0'/>
      <address type='drive' controller='0' bus='0' target='0' unit='0'/>
    </disk>
...
</domain>

Run the following commands from the host to eject the disk and reboot using virsh, as root. If you are using virt-manager, the commands below will work, but you can also use the GUI to detach and reboot it by manually stopping and starting.

# virsh attach-disk --type cdrom --mode readonly fedora "" hda
# virsh reboot fedora

Install the ACPI service

To enable the hypervisor to reboot or shutdown an instance, you must install and run the acpid service on the guest system.

Log in as root to the Fedora guest and run the following commands to install the ACPI service and configure it to start when the system boots:

# dnf install acpid
# systemctl enable acpid

Configure cloud-init to fetch metadata

An instance must interact with the metadata service to perform several tasks on start up. For example, the instance must get the ssh public key and run the user data script. To ensure that the instance performs these tasks, use the cloud-init package.

The cloud-init package automatically fetches the public key from the metadata server and places the key in an account. Install cloud-init inside the Fedora guest by running:

# yum install cloud-init

The account varies by distribution. On Fedora-based virtual machines, the account is called fedora.

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:

users:
  - name: admin
    (...)

Install cloud-utils-growpart to allow partitions to resize

In order for the root partition to properly resize, install the cloud-utils-growpart package, which contains the proper tools to allow the disk to resize using cloud-init.

# dnf install cloud-utils-growpart

Disable the zeroconf route

For the instance to access the metadata service, you must disable the default zeroconf route:

# echo "NOZEROCONF=yes" >> /etc/sysconfig/network

Configure console

For the nova console-log command to work properly on Fedora, you might need to do the following steps:

Edit the /etc/default/grub file and configure the GRUB_CMDLINE_LINUX option. Delete the rhgb quiet and add console=tty0 console=ttyS0,115200n8 to the option. For example:
```
...
GRUB_CMDLINE_LINUX="rd.lvm.lv=fedora/root rd.lvm.lv=fedora/swap console=tty0 console=ttyS0,115200n8"
```

Run the following command to save the changes:

# grub2-mkconfig -o /boot/grub2/grub.cfg
Generating grub configuration file ...
Found linux image: /boot/vmlinuz-4.10.10-200.fc25.x86_64
Found initrd image: /boot/initramfs-4.10.10-200.fc25.x86_64.img
Found linux image: /boot/vmlinuz-0-rescue-c613978614c7426ea3e550527f63710c
Found initrd image: /boot/initramfs-0-rescue-c613978614c7426ea3e550527f63710c.img
done

Shut down the instance

From inside the instance, run as root:

# poweroff

Clean up (remove MAC address details)

The operating system records the MAC address of the virtual Ethernet card in locations such as /etc/sysconfig/network-scripts/ifcfg-eth0 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.

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

# virt-sysprep -d fedora

Undefine the libvirt domain

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

# virsh undefine fedora

Image is complete

The underlying image file that you created with the qemu-img create command is ready to be uploaded. For example, you can upload the /tmp/fedora.qcow2 image to the Image service by using the openstack image create command. For more information, see the Create or update an image.

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