It can be confusing to new users for make-base-vm to create a lucid vm
by default, so switch to xenial, which is also a LTS release, but isn't
EOL yet. Using lucid with gitian-builder is broken anyway, because
lucid has been moved to old-releases.ubuntu.com since it is EOL and
gitian-builder doesn't support old-releases.ubuntu.com.
Now, if a user is using something like on-target directly, that user
doesn't need to set the DISTRO or TUSER variables if using Ubuntu guests
(so the scripts function the same as they did before Debian guest
support was added).
For example Ubuntu installs a bridge called `virbr0` by default for LXC.
Using this system-provided bridge avoids having to configure one
specifically before gitian building.
This commits makes it possible to override the bridge used by gitian
using the environment variable LXC_BRIDGE. The default is still to use
`br0` as before.
I was running into trouble using gitian LXC INSIDE a VirtualBox VM, because
the 10.0.2.x IP range overlaps with the range that VirtualBox uses for
its internal NAT network.
This commit makes it possible to override the host and guest IP that
is used during LXC image creation and the build, using environment variables:
- `GITIAN_HOST_IP` (default=10.0.2.2, host IP from the viewpoint of the
VM, can be used for both LXC and KVM)
- `LXC_GUEST_IP` (default=10.0.2.5, guest IP from the viewpoint of the
host, effective for LXC only)
When these are not defined the behavior remains the same as before.