I have a server at home running Ubuntu 12.04 which has grown messy over the years. I have fiddled with various packages, desktop environments (for VNC) etc. and I would like to reinstall it to start again, and have better control over what goes into the box.

But I want to keep much of the configurations after reinstallation, like LVM configuration, apache2, samba, etc etc. There would ideally exist a program which could analyze /etc, installed packages and such, store the information, and selectively put it back into the new installation.

I am even considering installing Ubuntu server on a virtual machine, just to be able to compare the contents of /etc with a clean installation, and even perform a migration to the virtual machine first, to verify that the transfer process works.

How do one go about performing this kind of reinstallation? Have anyone seen any resources on the net on the topic?