The Openstack metadata service exposes the EC2 API. We use the
existing `ec2.nix` module to configure the hostname and ssh keys of an
Openstack Instance.
A test checks the ssh server is well configured.
This is mainly to reduce the size of the image (700MB). Also,
declarative features provided by cloud-init are not really useful
since we would prefer to use our `configuration.nix` file instead.
We now make it happen later in the boot process so that multi-user
has already activated, so as to not run afoul of the logic in
switch-to-configuration.pl. It's not my favorite solution, but at
least it works. Also added a check to the VM test to catch the failure
so we don't break in future.
Fixes #23121
We now generate a qcow2 image to prevent hitting Hydra's output size
limit. Also updated /root/user-data -> /etc/ec2-metadata/user-data.
http://hydra.nixos.org/build/33843133
