VOLUME statement behavior in legacy builder vs. BuildKit

[nathanweeks]

Is this a docs issue?

• [X] My issue is about the documentation content or website

Type of issue

Information is incorrect

Description

The "Notes about specifying volumes" section mentions

• Changing the volume from within the Dockerfile: If any build steps change the data within the volume after it has been declared, those changes will be discarded.

This is apparently true for the legacy builder, but not for BuildKit (https://github.com/moby/moby/issues/37176#issuecomment-470951814):

BuildKit has a slightly different behaviour, where VOLUME statements are not applied during build, so it will actually modify the files that were originally in the given location, and only attach a volume when the container is run.

Location

https://docs.docker.com/engine/reference/builder/

Suggestion

Perhaps note the difference in behavior between the legacy builder and BuildKit?

[docker-robot[bot]]

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[nathanweeks]

/remove-lifecycle stale