Glossary
Configuration Drift
Configuration drift is the gradual divergence between what a system's configuration is documented or defined to be and what's actually running on it — accumulating one small, direct, undocumented change at a time, often made under time pressure during an incident and never reconciled back into the official definition afterward. Individually, each change usually seemed justified; collectively, they leave the running system meaningfully different from what anyone reviewing the documented configuration would expect.
Drift is a security concern specifically because the documented configuration is often what gets reviewed for correctness and access-control soundness — a review of the intended state provides limited assurance about the actual state once the two have quietly diverged. Immutable infrastructure is one deliberate way to prevent this gap from opening in the first place, rather than trying to detect and reconcile it after the fact.