Add “Immutable infrastructure” to glossary (#45656)

* Add “Immutable infrastructure” to glossary

* Add “Immutable infrastructure” to glossary

Co-authored-by: Tim Bannister <[email protected]>

* Add “Immutable infrastructure” to glossary

Co-authored-by: Tim Bannister <[email protected]>

* Add “Immutable infrastructure” to glossary

Co-authored-by: Tim Bannister <[email protected]>

---------

Co-authored-by: Tim Bannister <[email protected]>

Author: dev-johnn

content/en/docs/reference/glossary/immutable-infrastructure.md

@@ -0,0 +1,26 @@
+---
+title: Immutable Infrastructure
+id: immutable-infrastructure
+date: 2024-03-25
+full_link:
+short_description: >
+  Immutable Infrastructure refers to computer infrastructure (virtual machines, containers, network appliances) that cannot be changed once deployed
+
+aka: 
+tags:
+- architecture
+---
+ Immutable Infrastructure refers to computer infrastructure (virtual machines, containers, network appliances) that cannot be changed once deployed.
+
+<!--more-->
+
+Immutability can be enforced by an automated process that overwrites unauthorized changes or through a system that won’t allow changes in the first place.
+{{< glossary_tooltip text="Containers" term_id="container" >}} are a good example of immutable infrastructure because persistent changes to containers
+can only be made by creating a new version of the container or recreating the existing container from its image.
+
+By preventing or identifying unauthorized changes, immutable infrastructures make it easier to identify and mitigate security risks. 
+Operating such a system becomes a lot more straightforward because administrators can make assumptions about it.
+After all, they know no one made mistakes or changes they forgot to communicate.
+Immutable infrastructure goes hand-in-hand with infrastructure as code where all automation needed
+to create infrastructure is stored in version control (such as Git).
+This combination of immutability and version control means that there is a durable audit log of every authorized change to a system.