virtualization script should accept standard URLs OR filesystem paths

[Jeff Lane ]

Currently, getting the cloud image is only possible one of two ways:

1: Specify a local file system path to a copy of the cloud image in the config file, or an env var:
KVM_IMAGE=/path/to/cloud.img

2: Specify NOTHING and the script downloads it directly from http://cloud-images.ubuntu.com

However, this could be greatly expanded to allow for custom URLs for local or remote locations, or local paths.

For example, perhaps I want to specify a special image hosted on a MAAS server:

KVM_IMAGE="http://maasserver.com/images/cloud.img"

[Jeff Lane  (bladernr)]

Here's what happens when you specify nothing:
ubuntu@xwing:~$ ./virtualization kvm --debug
Executing KVM Test
WARNING:root:Config file /etc/xdg/virtualization.cfg was not found
WARNING:root:Now looking for ENV variables and command line arguments instead
DEBUG:root:Starting KVM Test
DEBUG:root:No image specified, downloading one now.
DEBUG:root:Downloading xenial-server-cloudimg-amd64-disk1.img, from http://cloud-images.ubuntu.com
(script modified to exit at this point)

[Jeff Lane  (bladernr)]

This is what happens now when you use a local file with a path specified in the config file, which is passed into the script via ENV VAR by checkbox-ng:

ubuntu@xwing:~$ KVM_IMAGE=/image/xenial-server-cloudimg-amd64-disk1.img ./virtualization kvm --debug
Executing KVM Test
WARNING:root:Config file /etc/xdg/virtualization.cfg was not found
WARNING:root:Now looking for ENV variables and command line arguments instead
DEBUG:root:Starting KVM Test
DEBUG:root:Cloud image location specified: /image/xenial-server-cloudimg-amd64-disk1.img.
DEBUG:root:Downloading image now
DEBUG:root:Cloud image exists locally at /image/xenial-server-cloudimg-amd64-disk1.img
(script modified to exit at this point)

[Jeff Lane  (bladernr)]

Now, lets pass the local file, using an actual URL:

ubuntu@xwing:~$ KVM_IMAGE=file:///image/xenial-server-cloudimg-amd64-disk1.img ./virtualization kvm --debug
Executing KVM Test
WARNING:root:Config file /etc/xdg/virtualization.cfg was not found
WARNING:root:Now looking for ENV variables and command line arguments instead
DEBUG:root:Starting KVM Test
DEBUG:root:Cloud image location specified: file:///image/xenial-server-cloudimg-amd64-disk1.img.
DEBUG:root:Downloading image now
DEBUG:root:Cloud image exists locally at /image/xenial-server-cloudimg-amd64-disk1.img
(script modified to exit at this point)

[Jeff Lane  (bladernr)]

OK... after tweaking... here is what you get when specifying a pure path, or a path URL with file://:

ubuntu@xwing:~$ KVM_IMAGE=file:///image/xenial-server-cloudimg-amd64-disk1.img ./virtualization kvm --debug
Executing KVM Test
WARNING:root:Config file /etc/xdg/virtualization.cfg was not found
WARNING:root:Now looking for ENV variables and command line arguments instead
DEBUG:root:Starting KVM Test
DEBUG:root:Cloud image location specified: file:///image/xenial-server-cloudimg-amd64-disk1.img.
DEBUG:root:Cloud image exists locally at /image/xenial-server-cloudimg-amd64-disk1.img
ubuntu@xwing:~$ KVM_IMAGE=/image/xenial-server-cloudimg-amd64-disk1.img ./virtualization kvm --debug
Executing KVM Test
WARNING:root:Config file /etc/xdg/virtualization.cfg was not found
WARNING:root:Now looking for ENV variables and command line arguments instead
DEBUG:root:Starting KVM Test
DEBUG:root:Cloud image location specified: /image/xenial-server-cloudimg-amd64-disk1.img.
DEBUG:root:Cloud image exists locally at /image/xenial-server-cloudimg-amd64-disk1.img

[Jeff Lane  (bladernr)]

This is with an absolute URL:
ubuntu@xwing:~$ KVM_IMAGE=http://10.0.0.1/images/xenial-server-cloudimg-amd64-disk1.img ./virtualization kvm --debug
Executing KVM Test
WARNING:root:Config file /etc/xdg/virtualization.cfg was not found
WARNING:root:Now looking for ENV variables and command line arguments instead
DEBUG:root:Starting KVM Test
DEBUG:root:Cloud image location specified: http://10.0.0.1/images/xenial-server-cloudimg-amd64-disk1.img.
DEBUG:root:Downloading xenial-server-cloudimg-amd64-disk1.img, from http://10.0.0.1

[Jeff Lane  (bladernr)]

This is with an incorrect relative URL:
ubuntu@xwing:~$ KVM_IMAGE=http://10.0.0.1/ ./virtualization kvm --debug
Executing KVM Test
WARNING:root:Config file /etc/xdg/virtualization.cfg was not found
WARNING:root:Now looking for ENV variables and command line arguments instead
DEBUG:root:Starting KVM Test
DEBUG:root:Cloud image location specified: http://10.0.0.1/.
DEBUG:root:Downloading xenial-server-cloudimg-amd64-disk1.img, from http://10.0.0.1/
ERROR:root:Failed download of image from http://10.0.0.1/: HTTP Error 404: Not Found

[Jeff Lane  (bladernr)]

With a correct relative URL:
ubuntu@xwing:~$ KVM_IMAGE=http://10.0.0.1/images/ ./virtualization kvm --debug
Executing KVM Test
WARNING:root:Config file /etc/xdg/virtualization.cfg was not found
WARNING:root:Now looking for ENV variables and command line arguments instead
DEBUG:root:Starting KVM Test
DEBUG:root:Cloud image location specified: http://10.0.0.1/images/.
DEBUG:root:Downloading xenial-server-cloudimg-amd64-disk1.img, from http://10.0.0.1/images/

[Jeff Lane  (bladernr)]

And finally with no URL specified

ubuntu@xwing:~$ ./virtualization kvm --debug
Executing KVM Test
WARNING:root:Config file /etc/xdg/virtualization.cfg was not found
WARNING:root:Now looking for ENV variables and command line arguments instead
DEBUG:root:Starting KVM Test
DEBUG:root:No image specified, downloading one now.
DEBUG:root:Downloading xenial-server-cloudimg-amd64-disk1.img, from http://cloud-images.ubuntu.com