Platform bootstrap for OpenStack Infrastructure

This is a terse guide on bootstrapping virtual-machine images for OpenStack infrastructure, with the goal of adding continuous-integration support for new platforms. It might also be handy if you are trying to replicate the upstream CI environment.

It covers deployment to Rackspace for testing; Rackspace is one of the major providers of capacity for the OpenStack Infrastructure project, so it makes a good place to start when building up your support story.

Firstly, get an Ubuntu Trusty environment to build the image in (other environments, like CentOS or Fedora, probably work -- but take this step to minimise differences to what the automated machinery of what upstream does). You want a fair bit of memory, and plenty of disk-space.

The tool used for building virtual-machine images is diskimage-builder. In short, it takes a series of elements, which are really just scripts run in different phases of the build process.

I'll describe building a Fedora image, since that's been my focus lately. We will use a fedora-minimal element -- this means the system is bootstrapped from nothing inside a chroot environment, before eventually being turned into a virtual-machine image (contrast this to the fedora element, which bases itself off the qcow2 images provided by the official Fedora cloud project). Thus you'll need a few things installed on the Ubuntu host to deal with bootstrapping a Fedora chroot

apt-get install yum yum-utils python-lzma

You will hit stuff like that python-lzma dependency on this road-less-travelled -- technically it is a bug that yum packages on Ubuntu don't depend on it; without it you will get strange yum errors about unsupported compression.

At this point, you can bootstrap your diskimage-builder environment. You probably want diskimage-builder from git, and then build up a virtualenv for your support bits and pieces.

git clone git://
virtualenv dib_env
. dib_env/bin/activate

pip install dib-utils

dib-utils is a small part of diskimage-builder that is split-out; don't think too much about it.

While diskimage-builder is responsible for the creation of the basic image, there are a number of elements provided by the OpenStack project-config repository that bootstrap the OpenStack environment. This does a lot of stuff, including caching all git trees (so CI jobs aren't cloning everything constantly) and running puppet setup.

git clone git://

There's one more trick required for building the VHD images that Rackspace requires; make sure you install the patched vhd-util as described in the script help.

At this point, you can probably build an image. Here's something approximating what you will want to do

break=after-error \
TMP_DIR=~/tmp \
ELEMENTS_PATH=~/project-config/nodepool/elements \
./bin/disk-image-create -x --no-tmpfs -t vhd \
   fedora-minimal vm devuser simple-init \
   openstack-repos puppet nodepool-base node-devstack

To break some of this down

  • break= will help you debug failing builds by dropping you into a shell when one of the element parts fail.

  • TMP_DIR should be set to somewhere with plenty of space; a default /tmp with tmpfs is probably restricted to a couple of gigabytes; not enough for a build.

  • ELEMENTS_PATH will add the OpenStack specific elements

  • DIB_DEV_USER_* flags will create a devuser login with a password and sudo access. This is really important as it is most likely you'll boot up fairly broken the first time, and you need a way to log-in (this is not used in "production").

  • DISTRO in this case says to build a Fedora 23 based-image, but will vary depending on what you are trying to do.

  • disk-image-create finally creates the image. We are telling it to create a vhd based image, using fedora-minimal in this case. For configuration we are using simple-init, which uses the glean project to configure networking from a configuration-drive.

    • By default, this will install glean from pypi. However, adding


      would modify the install to use the git source. This is handy if you have changes in there that are not released to pypi yet.

This goes and does its thing; it will take about 20 minutes. Depending on how far your platform diverges from the existing support, it will require a lot of work to get everything working so you can get an image out the other side. To see a rough example of what should be happening, see the logs of the official image builds that happen for a variety of platforms.

At some point, you should get a file image.vhd which is now ready to be deployed. The only reasonable way to do this is with shade. You can quickly grab this into the virtualenv we created before

pip install shade

Now you'll need to setup a clouds.yaml file to give yourself the permissions to upload the image. It should look something like

    profile: rackspace
       username: your_rax_username
       password: your_rax_password
       project_id: your_rax_accountnum
    - IAD

You should know your user-name and password (whatever you log into the website with), and when you login to Rackspace your project_id value is listed in the drop-down box labeled with your username as Account #. shade has no UI as such, so a simple script will do the upload.

import shade

cloud = shade.openstack_cloud(cloud='rax')
image = cloud.create_image('image-name', filename='image.vhd', wait=True)

Now wait -- this will also take a while. Even after upload it takes a fair while to process (you will see the shade debug output looping around some glance calls seeing if it is ready). If everything works, the script should return and you should be able to see the new image in the output of nova list-images.

At this point, you're ready to try booting! One caveat is that the Rackspace web interface does not seem to give you the option to boot with a configuration drive available to the host, essential for simple-init to bring up the network. So boot via the API with something like

nova boot --flavor=2 --image=image-uuid --config-drive 1 test-image

This should build and boot your image! This will allow you to open a whole new door of debugging to get your image booting correctly.

You can now iterate by rebuilding/uploading/booting as required. Note these are pretty big images, and uploaded in broken-up swift files, so I find swift delete --all helpful to reset between builds (obviously, I have nothing else in swift that I want to keep). The Rackspace java-based console UI is rather annoying; it cuts itself off every time the host reboots. This makes it quite difficult to catch the early bootup, or modify grub options via the boot-loader, etc. You might need to fiddle timeout options, etc in the image build.

If you've managed to get your image booting and listening on the network, you're a good-deal of the way towards having your platform supported in upstream OpenStack CI. At this point, you likely want to peruse the nodepool configuration and get an official build happening here. Once that is up, you can start the process of adding jobs that use your platform to test!

Don't worry, there's plenty more that can go wrong from here -- but you're on the way! OpenStack infra is a very dynamic environment, which many changes in progress; so in general, #openstack-infra on freenode is going to be a great place to start looking for help.