问在通过http安装时，为ubuntu使用的正确的virt位置url是什么？

EN

   -l, --location
       Syntax: -l, --location OPTIONS

       Distribution tree installation source. virt-install can recognize certain distribution trees and fetches a bootable kernel/initrd pair to launch the install.

       --location  allows  things  like --extra-args for kernel arguments, and using --initrd-inject. If you want to use those options with CDROM media, you can pass the ISO to --location as well which works
       for some, but not all, CDROM media.

       The LOCATION can take one of the following forms:

       https://host/path
              An HTTP server location containing an installable distribution image.

       ftp://host/path
              An FTP server location containing an installable distribution image.

       ISO    Extract files directly from the ISO path

       DIRECTORY
              Path to a local directory containing an installable distribution image.  Note that the directory will not be accessible by the guest after initial boot, so the OS installer  will  need  another
              way to access the rest of the install media.

       Some distro specific url samples:

       Fedora/Red Hat Based
              https://download.fedoraproject.org/pub/fedora/linux/releases/29/Server/x86_64/os

       Debian https://debian.osuosl.org/debian/dists/stable/main/installer-amd64/

       Ubuntu https://us.archive.ubuntu.com/ubuntu/dists/wily/main/installer-amd64/

       Suse   https://download.opensuse.org/pub/opensuse/distribution/leap/42.3/repo/oss/

       Additionally,  --location  can  take  'kernel' and 'initrd' sub options. These paths relative to the specified location URL/ISO that allow selecting specific files for kernel/initrd within the install
       tree. This can be useful if virt-install/ libosinfo doesn't know where to find the kernel in the specified --location.

       For example, if you have an ISO that libosinfo doesn't know about called my-unknown.iso, with a kernel at 'kernel/fookernel' and initrd at 'kernel/fooinitrd', you can make this work with:

          --location my-unknown.iso,kernel=kernel/fookernel,initrd=kernel/fooinitrd