cdk files should not live in /root/cdk

[James Troup]

kubernetes-master units, as of at least 1.19, have a /root/cdk folder. This folder is a smörgåsbord containing config, secrets, logs, PID files and more. Please redistribute these files to something that is a little closer to FHS¹ compliance.

¹ https://en.wikipedia.org/wiki/Filesystem_Hierarchy_Standard

[George Kraft (cynerva)]

Our ability to adhere to FHS is somewhat limited due to snap confinement. We can move a lot of these files out of /root/cdk, but for the most part, they will have to live in /var/snap instead, e.g.

/var/snap/kube-apiserver/common/audit.log
/var/snap/kube-controller-manager/common/kubeconfig

etc.

[Adam Dyess (addyess)]

In LP#1936816, the auth-webhook.pid file is moving to /run/

[Adam Dyess (addyess)]

in my research of this bug, i did discover the filebeat charm has a fixed path to `/root/cdk/audit/*.log` baked into its template files. Perhaps this is better provided over a relation as to which files are important for including in the filebeat path.

https://git.launchpad.net/filebeat-charm/tree/templates/filebeat-5.yml#n11

Needless to say, moving the audit log would break filebeats.