Make `# check=` directive comment less positional

[ag-TJNII]

Description

I'm trying to disable a build warning with a # check=skip= comment. I'm finding this comment only takes effect if it is at the very top of the file. For example, the following works:

# check=skip=FailingCheck

[commands]

However, if I add a comment explaining why I'm disabling this, it doesn't work. The following example will result in the warning still being shown during a build.

# Comment with context about why this is disabled
# check=skip=FailingCheck

[commands]

Worse, I only want to disable this for a single stage. The following also doesn't work:

# Build stage
[commands]

# Output stage
# This needs [thing that triggers FailingCheck] due to [reasons]
# check=skip=FailingCheck
[Line that triggers FailingCheck]

[core commands]

It would be nice if I could put the check skip command next to the line causing the violation, so that it is in context. At the minimum I'd like to be able to put a comment above it explaining why the check was disabled. Thanks.

[tonistiigi]

#check= is a Dockerfile directive and these need to be in the top of the file https://docs.docker.com/reference/dockerfile/#parser-directives . You can put your description in the comments afterwards.

There has also been discussion of allowing skip for a specific line, not for the whole file. This has been accepted but there is no PR iirc.

[ag-TJNII]

The per-line skip would meet the desire of the final example.

For the comment example I see the following in: From https://docs.docker.com/reference/dockerfile/#parser-directives

Once a comment, empty line or builder instruction has been processed, BuildKit no longer looks for parser directives

I think halting the parser directive search on comments is too strict, and it inhibits putting explanation comments before the directive, which is how most code flows. I'd like to keep this issue open to request an enhancement that Buildkit not halt the directive search on comments.