(This is a small fixup to the main change, which was accidentally
included in a previous commit:
08bbd7e61 "settings: Slightly simplify EMAIL_BACKEND logic."
Oops. See there for most of the changes described here.)
The installer works out of a release-tarball tree. We typically want
to share this tree between successive test-install runs (with an rsync
or similar command to update source files of interest) because
rebuilding a release tree from scratch is slow. But the installer
will munge the tree; so instead of directly bind-mounting the tree
into the container, we need to give it an overlay over the tree, as a
sandbox to play in.
Previously we used lxc-copy's `-m overlay=...` feature to do this,
mounting an overlay in the container. But then sometimes in
development we want to reach in and edit some code in the tree,
e.g. before rerunning the installer after something failed. Reaching
inside the container for this is a pain (`ssh` would add latency, and
I haven't installed sshd in the containers; and getting rsync to work
with `lxc-attach` was beyond what I could figure out in a few minutes
of fiddling); and editing the base tree often doesn't work.
So, create the overlay with our own `mount -t overlay`, and have
`lxc-copy` just bind-mount that in. Now the host has direct access to
the same overlay which the guest is working from.
Also this makes it past time to help the user out in finding the fresh
names we've created: first the container, now this shared tree. Print
those at the end, rather than make the user scroll to the top and find
the right `set -x` line to copy-paste from.
9476a3a334