No code changes. Rebuilds the box with a current debootstrap run and apt package versions, this e.g. removes the expired letsencrypt "DST X3" certificate from the trust store.

Note that I had to apply this patch before running make bionic, otherwise the build got stuck at an apt confirmation prompt:

--- /usr/share/lxc/templates/lxc-ubuntu~    2021-10-06 10:51:31.710185270 +0000
+++ /usr/share/lxc/templates/lxc-ubuntu 2021-10-06 10:51:23.289977575 +0000
@@ -428,6 +428,7 @@
     (
         cat << EOF
         mount -t proc proc "${1}/partial-${arch}/proc"
+        export DEBIAN_FRONTEND=noninteractive
         chroot "${1}/partial-${arch}" apt-get dist-upgrade -y
 EOF
     ) | lxc-unshare -s MOUNT -- sh -eu || (suggest_flush; false)

Make resolving other lxc container names work, by disabling the use of systemd-resolved.

• systemd bugreport
• workaround, which is a supported (but not the recommended ;) mode of operation, according to the manpage:

rm -f /etc/resolv.conf
ln -s ../run/systemd/resolve/resolv.conf /etc/resolv.conf

Disables automatic apt activity (see e.g. https://github.com/chef/bento/issues/609).

Now built with our own fork containing said fix: https://github.com/ZeitOnline/vagrant-lxc-base-boxes/tree/bionic

Initial release, built on a 18.04 VM by running obnoxxx/vagrant-lxc-base-boxes as-is:

cat > Vagrantfile <<EOF
Vagrant.configure("2") do |config|
  config.vm.define "default" do |default|
    default.vm.box = "bento/ubuntu-18.04"
  end
end
EOF
vagrant up
vagrant ssh

# Inside Vagrant VM
sudo apt-get install lxc lxc-templates
wget https://releases.hashicorp.com/vagrant/2.2.0/vagrant_2.2.0_x86_64.deb
sudo dpkg -i vagrant*.deb
sudo locale-gen en_US.UTF-8  # it breaks with locale=C
export LANG=en_US.UTF-8 LC_ALL=en_US.UTF-8
# bionic support available via https://github.com/obnoxxx/vagrant-lxc-base-boxes/pull/28
git clone git://github.com/dartvaper/vagrant-lxc-base-boxes.git
git checkout bionic_support
make bionic
cp output/*/*.box /vagrant