I would like to track the storage capacity changes of user shares over time,

in order to evaluate future capacity needs.

I there any plugin/docker that enables this functionality?

 

Thanks.

It is already built in.  Go to  Shares   then   Disk Shares   and under the Size column, click on   Compute    for the shares you are interested.  Copy down numbers (or print out the page)  and post into a spread sheet.  

Thanks, but I want it done automatically on a daily or weekly basis,

not to have one more task on my to-do list.