
Specifies the URL to download. All downloads are checksummed using ``md5sum``
and ``sha256sum``

URLs are checked during the test job validation to ensure that the file can be
downloaded. Missing files will cause the test job to end as Incomplete.

URLs **must** use one of the supported schemes, the first element of the URL.

.. topic:: Supported schema

 * ``http://``
 * ``https://``
 * ``file://``
 * ``lxc://``

