Linux Kickstart Snippet RHEL 6 to 7 Installation with Preservation of File System and LVM

An interesting problem was presented to me:

A customer wanted to install (not upgrade) fresh Red Hat Enterprise Linux RHEL 7.1 on current RHEL 6.6 server, with preservation of LVM structure and keeping data in file system /extra (part of root volume group) intact.

In other words, they did not want to reinitialise the boot disk, and did not want to lose any data in file system /extra.

After some planning and testing, these were the relevant snippets from the Kickstart file that worked well.

zerombr
clearpart --none --initlabel
part pv.00 --onpart=/dev/sda1
partition /boot --fstype="ext4" --onpart=/dev/sda1
part pv.01 --fstype=LVM --onpart=/dev/sda2 --noformat
logvol / --fstype="ext4" --useexisting --name=root --vgname=vgos
logvol /home --fstype="ext4" --useexisting --name=home --vgname=vgos
logvol /opt --fstype="ext4" --useexisting --name=opt --vgname=vgos
logvol /usr --fstype="ext4" --useexisting --name=usr --vgname=vgos
logvol /var --fstype="ext4" --useexisting --name=var --vgname=vgos
logvol /var/log --fstype="ext4" --useexisting --name=varlog --vgname=vgos
logvol /var/log/audit --fstype="ext4" --useexisting --name=audit --vgname=vgos
logvol /tmp --fstype="ext4" --useexisting --name=tmp --vgname=vgos
logvol swap --fstype="swap" --useexisting --name=swap --vgname=vgos
logvol /extra --fstype="ext4" --noformat --name=lvex --vgname=vgos