This may be a juju anti-pattern but is there a way of customising application configuration on a per-unit basis?
To provide a concrete example of where this might be useful I have deployed charmed openstack which provides 1 or more units of the
nova-compute application depending on the number of compute nodes. I have heterogeneous hardware and I’d like to be able to set different values for
reserved-host-memory, for each compute node. This is supported by nova by modifying
/etc/nova/nova.conf on the relevant host however
juju config nova-compute reserved-host-memory=<new_number> will modify all instances of
nova-compute, and there doesn’t appear to be a way to constrain this change to a particular unit/machine/other_relevant_entity.