MENTAL MODEL · M2121

Immutable Infrastructure

CultureHigh supportPhilosophy

Included

Version 1.0.0 · Updated 2026-07-31

CORE DEFINITION

Refers to the practice of never modifying a server after it has been deployed. If updates or fixes are needed, the old server is destroyed and a new one is deployed, rather than patching the existing one.

SCAFFOLDING EFFECT

psychology

Reduce cognitive load

Eliminates configuration drift. It embodies the philosophy of "replace over repair." When dealing with complex legacy issues (such as bad code or bad systems), sometimes starting over (Immutable) is safer and more efficient than patching (Mutable).

anchor

Anchor fast decisions

Long-lived mutable infrastructure accumulates "configuration drift" due to piecemeal changes (inconsistent environments, unreproducible states), making troubleshooting difficult and rollback hard. The immutable pattern replaces "in-place modification" with "fresh deployment + destroy old," ensuring consistency, versionability, and one-click rollback. The idea extends to "replace over repair"—when the cumulative cost of modifying an object exceeds rebuilding, starting over is safer.

MINIMUM ACTION

In progress 0/5

Practice this model in one real situation:

Image-based: Make environments/services into versioned immutable images.
No in-place changes: Changes only via new deployments, never modify running instances.
Replace rather than repair: When updates are needed, build new, switch traffic, and retire old.
Rollback capability: Keep old versions to switch back in case of issues.
Metaphor transfer: For "bad code/bad systems," evaluate rebuild vs. patch costs.

Check to track your progress (stored locally)

Learning progress0%

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Source support: Explicit

link
ibm.comhttps://www.ibm.com/think/topics/immutable-infrastructureZH · Explicit
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