Automatic rollback of broken configuration changes?

Question

I run a headless home server and sometimes need to make configuration changes that have the potential to break remote access. Is there a tool or system service that can be set to define what constitutes a "good" state (e.g. can ping 1.1.1.1 and some remote host can see me) and have it roll back changes automatically if it detects a "bad" state? I saw one answer that provides a very targeted suggestion, but I'm looking for something more general that I can leave running all the time.

In a perfect world, it would look like it literally rolled back time. But I don't want to run a VM, so I'll settle for detecting and automatically restoring files I manually edit under /etc. It would even be valuable to have a service automatically roll back all changes to /etc and reboot the system unless I specifically indicate the new state is good within five minutes of the change being made.

Is there any package or service that does this?

Answer 1

Timeshift can be used to achieve your goal. In a headless Debian server, Timeshift provide a CLI tool.

Install:

sudo apt install timeshift

Basic cli options from manpages:

List:
  --list[-snapshots]         List snapshots

Backup:
   --create                   Create snapshot (even if not scheduled)

Restore:
  --restore                  Restore snapshot
  --clone                    Clone current system

Delete:
  --delete                   Delete snapshot

Examples:
timeshift --create --comments "after update" --tags D
timeshift --restore --snapshot '2014-10-12_16-29-08' --target /dev/sda1
timeshift --delete  --snapshot '2014-10-12_16-29-08'

Answer 2

You describe various concepts:

Revision control

This is a tool that lets you role back source-code or configurations.

Automatic deployment

Have configurations that are added to revision control automatically deployed.

Automated test

Code or configurations are tested before or after deployment. If done before, then a pass can trigger deployment. If done after, then a fail can trigger rollback.