avocado.utils.vmimage

This utility provides a API to download/cache VM images (QCOW) from the official distributions repositories.

Basic Usage

Import vmimage module:

>>> from avocado.utils import vmimage

Get an image, which consists in an object with the path of the downloaded/cached base image and the path of the external snapshot created out of that base image:

>>> image = vmimage.get()
>>> image
<Image name=Fedora version=26 arch=x86_64>
>>> image.name
'Fedora'
>>> image.path
'/tmp/Fedora-Cloud-Base-26-1.5.x86_64-d369c285.qcow2'
>>> image.get()
'/tmp/Fedora-Cloud-Base-26-1.5.x86_64-e887c743.qcow2'
>>> image.path
'/tmp/Fedora-Cloud-Base-26-1.5.x86_64-e887c743.qcow2'
>>> image.version
26
>>> image.base_image
'/tmp/Fedora-Cloud-Base-26-1.5.x86_64.qcow2'

If you provide more details about the image, the object is expected to reflect those details:

>>> image = vmimage.get(arch='aarch64')
>>> image
<Image name=FedoraSecondary version=26 arch=aarch64>
>>> image.name
'FedoraSecondary'
>>> image.path
'/tmp/Fedora-Cloud-Base-26-1.5.aarch64-07b8fbda.qcow2'

>>> image = vmimage.get(version=7)
>>> image
<Image name=CentOS version=7 arch=x86_64>
>>> image.path
'/tmp/CentOS-7-x86_64-GenericCloud-1708-dd8139c5.qcow2'

Notice that, unlike the base_image attribute, the path attribute will be always different in each instance, as it actually points to an external snapshot created out of the base image:

>>> i1 = vmimage.get()
>>> i2 = vmimage.get()
>>> i1.path == i2.path
False

Custom Image Provider

If you need your own Image Provider, you can extend the vmimage.IMAGE_PROVIDERS list, including your provider class. For instance, using the vmimage utility in an Avocado test, we could add our own provider with:

from avocado import Test

from avocado.utils import vmimage

class MyProvider(vmimage.ImageProviderBase):

    name = 'MyDistro'

    def __init__(self, version='[0-9]+', build='[0-9]+.[0-9]+',
                 arch=os.uname()[4]):
        """
        :params version: The regular expression that represents
                         your distro version numbering.
        :params build: The regular expression that represents
                       your build version numbering.
        :params arch: The default architecture to look images for.
        """
        super(MyProvider, self).__init__(version, build, arch)

        # The URL which contains a list of the distro versions
        self.url_versions = 'https://dl.fedoraproject.org/pub/fedora/linux/releases/'

        # The URL which contains a list of distro images
        self.url_images = self.url_versions + '{version}/CloudImages/{arch}/images/'

        # The images naming pattern
        self.image_pattern = 'Fedora-Cloud-Base-{version}-{build}.{arch}.qcow2$'

class MyTest(Test):

    def setUp(self):
        vmimage.IMAGE_PROVIDERS.add(MyProvider)
        image = vmimage.get('MyDistro')
        ...

    def test(self):
        ...

Supported images

The vmimage library has no hardcoded limitations of versions or architectures that can be supported. You can use it as you wish. This is the list of images that we tested and they work with vmimage:

Provider	Version	Architecture
centos	8	aarch64
centos	8	ppc64le
centos	8	x86_64
centos	7	x86_64
cirros	0.5.2	arm
cirros	0.5.2	aarch64
cirros	0.5.2	i386
cirros	0.5.2	ppc64
cirros	0.5.2	ppc64le
cirros	0.5.2	powerpc
cirros	0.5.2	x86_64
cirros	0.4.0	arm
cirros	0.4.0	aarch64
cirros	0.4.0	i386
cirros	0.4.0	ppc64
cirros	0.4.0	ppc64le
cirros	0.4.0	powerpc
cirros	0.4.0	x86_64
debian	9.13.28-20211002	arm64
debian	9.13.28-20211002	amd64
debian	10.11.0	arm64
debian	10.11.0	amd64
fedora	33	aarch64
fedora	33	ppc64le
fedora	33	s390x
fedora	33	x86_64
fedora	34	aarch64
fedora	34	ppc64le
fedora	34	s390x
fedora	34	x86_64
ubuntu	18.04	aarch64
ubuntu	18.04	ppc64el
ubuntu	18.04	s390x
ubuntu	18.04	x86_64
ubuntu	20.10	aarch64
ubuntu	20.10	ppc64el
ubuntu	20.10	s390x
ubuntu	20.10	x86_64
ubuntu	21.04	aarch64
ubuntu	21.04	ppc64el
ubuntu	21.04	s390x
ubuntu	21.04	x86_64
opensuse	15.1	aarch64
opensuse	15.1	x86_64
opensuse	15.2	x86_64