Configuration Management Tools and Rollbacks / Approaching Immutable Infrastructure

Question

I am interested in whether there are any configuration management tools out there that make it easy to roll back.

So far it seems that with Ansible, Chef, and Puppet you have to write the roll back tasks/recipes/whatever to get back to your previous state.

Coming from a bit of personal interest and experience with NixOS I have seen that with pure Immutable Infrastructure rollback is easy.

I am in Enterprise environments where NixOS is not happening. How can Enterprises begin to approach Rollbacks better with tools that work with Windows and Enterprise Linux Distros?

Answer 1

You hint in the title about immutable infrastructure, so it sounds like you already know the solution: don't change existing servers, but bring up new ones with your changes, switch over to them, and switch back to the old ones if necessary.

Theoretically any of the standard config management tools can roll back by simply checking out a previous commit and rerunning the config. However, practically speaking this often isn't the case, as you may have introduced a new config rule (and so whatever it is doing is simply ignored in older versions) or you've written a rule that isn't easily reversible (for instance, does some destructive data operation). If you were very careful in how you always write your playbooks, you could avoid this, but a few less error-prone solution is just to use an immutable infrastructure approach.