Rollbacks and Immutable Infrastructure

A rollback moves a system from a broken state back to a known good state. Immutable infrastructure is the practice of building infrastructure once and never modifying it in place, so that "a known good state" exists as a concrete artifact the team can return to.

In a mutable world, "rolling back" means trying to undo changes on a running server: config files edited, packages upgraded, months of accumulated state both intentional and accidental. The pre-change state exists only as a memory. In an immutable world, rolling back is deploying an older artifact from a registry and shifting traffic away from the new one. It is a controlled action, not a recovery effort.