Create a KVM Based Debian 7 OpenStack Cloud Image

Monday, April 7, 2014

Unlike Red Hat, Fedora, CentOS, and Canonical, Debian does not create and distribute OpenStack cloud images. It is up to you to create your own.

I have seen steps using packer templates or virt-builder to create Debian 7 OpenStack cloud images, but I have not seen a step-by-step manual process to understand how it all works.

This post will be that step-by-step manual process of creating a Debian 7 OpenStack cloud image. Many of the steps were derived from the links mentioned above as well as other links in the References section below.

The following steps will require you to have access to a Linux distribution that has KVM/QEMU and libvirt installed.

Install KVM/QEMU and libvirt

If you happen to be using a Linux distribution that does not have any virtualization packages installed, the following packages will be needed depending on which Linux distribution you are running.


Install the necessary repository packages:

yum groupinstall "Virtualization" "Virtualization Platform"

Enable and start the libvirtd service on CentOS 6 or RHEL 6:

chkconfig libvirtd on

service libvirtd start

Enable and start the libvirtd service on Fedora 17 and newer:

systemctl enable libvirtd

systemctl start libvirtd


Install the necessary repository packages:

sudo apt-get install qemu-kvm libvirt-bin virt-manager

Start the libvirt-bin service:

service libvirt-bin start

Create the Virtual Machine

You can create the Debian 7 virtual machine using the following command. It will pull everything it needs from the official Debian repositories. Depending on the speed of your internet connection, the install may take anywhere from 5 - 20 minutes:

sudo virt-install --virt-type kvm --name debian-7 --ram 1024 --location= --disk path=/tmp/debian-7-amd64-vm.img,size=5 --network network=default --graphics vnc,listen= --noautoconsole --os-type=linux --os-variant=debianwheezy --extra-args="priority=critical interface=auto debian-installer/language=en debian-installer/country=US debian-installer/locale=en_US keymap=us preseed/url="

Once the install finishes, the virtual machine will automatically shutdown. Start it back up and proceed to the next section.

Post-install Steps

With the base install of Debian 7 in place, it is time for you to configure the operating system to work with OpenStack.

Using the KVM console or SSH, login as the root user (password is debian).

Add the Debian Wheezy Backports repository to apt so you can install the cloud-init packages:

echo 'deb wheezy-backports main' >> /etc/apt/sources.list

Update apt-get so it sees the new repository:

apt-get update

Install all of the necessary cloud-init packages along with some other packages:

apt-get install sudo curl wget rsync cloud-init cloud-utils cloud-initramfs-growroot

Replace the default /etc/cloud/cloud.cfg with the following contents:

# The top level settings are used as module
# and system configuration.

# A set of users which may be applied and/or used by various modules
# when a 'default' entry is found it will reference the 'default_user'
# from the distro configuration specified below
   - default

# If this is set, 'root' will not be able to ssh in and they
# will get a message to login instead as the above $user (ubuntu)
disable_root: true

# This will cause the set+update hostname module to not operate (if true)
preserve_hostname: false

# Example datasource config
# datasource:
# Ec2:
# metadata_urls: [ '' ]
# timeout: 5 # (defaults to 50 seconds)
# max_wait: 10 # (defaults to 120 seconds)

# The modules that run in the 'init' stage
 - migrator
 - bootcmd
 - write-files
 - resizefs
 - set_hostname
 - update_hostname
 - update_etc_hosts
 - ca-certs
 - rsyslog
 - users-groups
 - ssh

# The modules that run in the 'config' stage
# Emit the cloud config ready event
# this can be used by upstart jobs for 'start on cloud-config'.
 - emit_upstart
 - mounts
 - ssh-import-id
 - locale
 - set-passwords
 - grub-dpkg
 - apt-pipelining
 - apt-configure
 - package-update-upgrade-install
 - landscape
 - timezone
 - puppet
 - chef
 - salt-minion
 - mcollective
 - disable-ec2-metadata
 - runcmd
 - byobu

# The modules that run in the 'final' stage
 - rightscale_userdata
 - scripts-per-once
 - scripts-per-boot
 - scripts-per-instance
 - scripts-user
 - ssh-authkey-fingerprints
 - keys-to-console
 - phone-home
 - final-message
 - power-state-change

# System and/or distro specific settings
# (not accessible to handlers/transforms)
   # This will affect which distro class gets used
   distro: debian
   # Default user name + that default users groups (if added/used)
     name: debian
     lock_passwd: True
     gecos: Debian
     shell: /bin/bash
     groups: [adm, audio, cdrom, dialout, floppy, video, plugdev, dip, sudo]
     sudo: ["ALL=(ALL) NOPASSWD: ALL"]
   # Other config here will be given to the distro class and/or path classes
      cloud_dir: /var/lib/cloud/
      templates_dir: /etc/cloud/templates/
      upstart_dir: /etc/init/
     - arches: [default]

Change the GRUB configuration so the OpenStack console outputs the boot logs:

sed -i -e 's/^GRUB_CMDLINE_LINUX_DEFAULT=.*/GRUB_CMDLINE_LINUX_DEFAULT="console=ttyS0"/' /etc/default/grub

Update GRUB to apply the changes:


Change the networking configuration to work with cloud-init:

sed -i 's/allow-hotplug eth0/auto eth0/' /etc/network/interfaces

Clean up apt:

apt-get autoremove
apt-get autoclean
apt-get clean

Remove everything in the /tmp directory:

rm -rf /tmp/*

Clean up the last logged in users logs:

rm -f /var/log/wtmp /var/log/btmp

Clean up the command history:

history -c

Shutdown the virtual machine:

shutdown -h now

Compress the Image

The virt-install command above created the virtual machine’s backing disk file at /tmp/debian-7-amd64-vm.img and the final file size will be about 5 GB. Typically, OpenStack images are not this large, and there is a lot of useless space within the current image. So, use the qemu-img command to compress the image to about 500 MB:

qemu-img convert -c /tmp/debian-7-amd64-vm.img -O qcow2 /tmp/debian-7-amd64.img

Upload the Image into the Glance Repository

With the final image created, it is time to upload it to the Glance Repository in your OpenStack environment.

You can upload the image into the Glance Repository from a local file path using the following command:

glance image-create --name debian-7-amd64 --disk-format=qcow2 --container-format=bare --file /tmp/debian-7-amd64.img

Or, you can upload the image into the Glance Repository from a URL using the following command:

glance image-create --name debian-7-amd64 --disk-format=qcow2 --container-format=bare --copy-from

With the image now uploaded into your Glance Repository, you can begin creating OpenStack Instances from it.

Your SSH public key will be injected into the debian user’s directory. So, when you login via SSH, login as that user. If you want to change this user modify the name parameter in the default_user section of the cloud-init config above.



virt-builder: Installing cloud-init in a Debian 7 guest

how to shrink the image requirements for disk

Chapter 3. OpenStack Linux image requirements

Example: Ubuntu image

preseeding debian netinstall does not get preseed file via http

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