What does "immutable tag" mean?

An "immutable tag" is an image tag that cannot be changed after publication. If a tag is marked as immutable, it cannot be overwritten with a new version of the image, only a different tag can be created.

#Why this is done

• to avoid a situation where the same tag points to different versions of an image;
• so that a deployment is always predictable;
• so that v1.0 today and v1.0 a year from now are the same image, byte for byte.

#Example

• myapp:1.0 - immutable
• myapp:latest - usually mutable (can be overwritten)

#In short

Immutable tag = a version of an image that cannot be changed after publication. This guarantees stability and repeatable builds.