[CentOS] Reduce existing CentOS 7 installation to "Minimal install" - services?

Hi,

When I install a CentOS server/desktop/workstation, I usually start from
scratch with a barebone minimal installation, then add packages as needed.

Some machines (like dedicated servers in a datacenter) come
preconfigured by the hosting company, so I thought it wouldn't be a bad
idea to start stripping that stuff first.

Here's a little script I wrote, which essentially strips down any
CentOS-7 installation to a minimal core system:

https://github.com/kikinovak/centos/blob/master/7.x/scripts/00-elaguer-paquets.sh

The script parses the 'minimal' package list and then just removes
everything that's not on the list.

Now I tried running that on an existing CentOS-7 "Web Server"
installation. I ran it, rebooted... and I got dropped to a console that
suggested to run journalctl. Uh oh.

I'm currently catching up with systemd and its specificities, working
through a bunch of online tutorials. But here's what I figured out so
far. Before stripping down my system, I have to reduce services to a
minimum. (On a Slackware system, which is what I'm using most of the
time, that's where I would disable pretty much all services besides
rc.syslog and rc.sshd.)

Now what would be the simple systemd equivalent of doing that? E. g. on
any CentOS installation (be it graphical, "Web Server", "File Server",
whatever), strip down services to the status that they're at just after
installing a "Minimal Install"?

Cheers from the sunny South of France,

Niki
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