zuul-jobs/dib-elements

Using diskimage-builder to build opendev-ci nodes

In addition to being able to just download and consume images that are the same as what run devstack, it's easy to make your own for local dev or testing - or just for fun.

Install diskimage-builder

Install the dependencies:

sudo apt-get install kpartx qemu-utils curl python-yaml debootstrap

Install diskimage-builder:

sudo -H pip install diskimage-builder

Build an image

Building an image is simple, we have a script!

bash tools/build-image.sh

See the script for environment variables to set distribution, etc. By default it builds an ubuntu-minimal based image. You should be left with a .qcow2 image file of your selected distribution.

Infra uses the -minimal build type for building Ubuntu/CentOS/Fedora. For example: ubuntu-minimal.

It is a good idea to set TMP_DIR to somewhere with plenty of space to avoid the disappointment of a full-disk mid-way through the script run.

While testing, consider exporting DIB_OFFLINE=true, to skip updating the cache.

Mounting the image

If you would like to examine the contents of the image, you can mount it on a loopback device using qemu-nbd.

sudo apt-get install qemu-utils
sudo modprobe nbd max_part=16
sudo mkdir -p /tmp/newimage
sudo qemu-nbd -c /dev/nbd1 /path/to/opendev-ci-node-precise.qcow2
sudo mount /dev/nbd1p1 /tmp/newimage

or use the scripts

sudo apt-get install qemu-utils
sudo modprobe nbd max_part=16
sudo tools/mount-image.sh opendev-ci-node-precise.qcow2
sudo tools/umount-image.sh

Other things

It's a qcow2 image, so you can do tons of things with it. You can upload it to glance, you can boot it using kvm, and you can even copy it to a cloud server, replace the contents of the server with it and kexec the new kernel.