I'm running ubuntu 16.04.
Let's say I want the system to run "mkdir /var/log/servicename" before starting the service (needed due to having /var/log in tmpfs).
Previously, with upstart, I edited the conffile /etc/init/servicename to add commands to it.
Now the service is being run through systemd, and the init config file for it, /lib/systemd/system/servicename is not a conffile, i.e. if edited it will be replaced on a package update.
What is the recommended way to solve this problem?