The plain-English version
A reusable filesystem change in a layered container image.
Why it matters
Layer structure affects build reuse, transfer size, and where files remain present.
Let’s make it click
Installing dependencies before copying frequently changing application code can allow reuse of an earlier build step.
Vibe Bro’s heads-up
Deleting a secret in a later layer does not safely erase it from earlier image history; keep secrets out of the build context and image.
The docs behind it
Documentation links checked .
Editorial review · October 28, 2026
Supported: Layer reuse/caching explanation is correct; deleting a secret in a later layer does not remove its earlier representation.