avocado.utils.vmimage

This utility provides an 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.Image.from_parameters()
>>> image
<Image name=Fedora version=35 arch=x86_64>
>>> image.name
'Fedora'
>>> image.path
'/tmp/by_location/951337e4bd3f30b584623d46f1745147cb32aca5/Fedora-Cloud-Base-35-1.2.x86_64-54d81da8.qcow2'
>>> image.version
35
>>> image.base_image
'/tmp/by_location/951337e4bd3f30b584623d46f1745147cb32aca5/Fedora-Cloud-Base-35-1.2.x86_64.qcow2'

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

>>> image = vmimage.Image.from_parameters(arch='aarch64)
>>> image
<Image name=Fedora version=35 arch=aarch64>
>>> image.name
'Fedora'
>>> image.path
'/tmp/by_location/3f1d3b1b568ad908eb003d1012ba79e1f3bb0d57/Fedora-Cloud-Base-35-1.2.aarch64-dab7007f.qcow2'

>>> image = vmimage.Image.from_parameters(version=34,name='fedora')
>>> image
<Image name=Fedora version=34 arch=x86_64>
>>> image.path
'/tmp/by_location/def0ea887952961473cfbfda268e77d66f9bcd14/Fedora-Cloud-Base-34-1.2.x86_64-0ed30cd9.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.Image.from_parameters()
>>> i2 = vmimage.Image.from_parameters()
>>> 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
None	None	None