So it turns out that this is not related to bionic support at all.
The root cause for this problem is that the charm thinks that the thruk service service is called thruk-master. It should be called thruk. The charm correctly populates /etc/thruk/thruk_local.conf but since the thruk service is not restarted /var/cache/thruk/lmd/lmd.ini is not updated.
This bug has probably existed since trusty since the playbook for thruk mentions that apache should be reloaded. This in turn reloads thruk and the config is generated correctly.
So it turns out that this is not related to bionic support at all.
The root cause for this problem is that the charm thinks that the thruk service service is called thruk-master. It should be called thruk. The charm correctly populates /etc/thruk/ thruk_local. conf but since the thruk service is not restarted /var/cache/ thruk/lmd/ lmd.ini is not updated.
This bug has probably existed since trusty since the playbook for thruk mentions that apache should be reloaded. This in turn reloads thruk and the config is generated correctly.