If dockerfile is ignored using double star pattern build fails to find dockerfile

[kerhong]

Description

If dockerfile is ignored in .dockerignore using a double star glob pattern (ex: **/docker, if dockerfile is a/b/docker/some.dockerfile) then, even if specified with --file parameter during build it will not be found.

Steps to reproduce the issue:

1. Create a directory structure (or clone https://github.com/kerhong/dockerignore-dockerfile-difference)

├── .dockerignore
├── explicitly-ignored-dir
│   └── explicitly-ignored-dir.dockerfile
├── explicitly-ignored.dockerfile
├── glob-one-star-ignore
│   └── glob-one-star-ignore.dockerfile
├── glob-two-star-ignore
│   └── glob-two-star-ignore.dockerfile
├── ignored-by-glob.ignore.dockerfile

and .dockerignore

.dockerignore

explicitly-ignored.dockerfile
*.ignore.dockerfile
**/glob-two-star-ignore
explicitly-ignored-dir
glob-one-star-ignore/*

2. Using docker build --file <FILE> . all dockerfiles are valid except glob-two-star-ignore/glob-two-star-ignore.dockerfile

Describe the results you received:
docker build --file glob-two-star-ignore/glob-two-star-ignore.dockerfile . fails with Error response from daemon: Cannot locate specified Dockerfile: glob-two-star-ignore/glob-two-star-ignore.dockerfile

Describe the results you expected:
docker build --file glob-two-star-ignore/glob-two-star-ignore.dockerfile . succeeds like all other dockerfiles in the example.

Output of docker version:

Client:
 Version:           19.03.3-ce
 API version:       1.40
 Go version:        go1.13.1
 Git commit:        a872fc2f86
 Built:             Wed Oct  9 02:28:51 2019
 OS/Arch:           linux/amd64
 Experimental:      false

Server:
 Engine:
  Version:          19.03.3-ce
  API version:      1.40 (minimum version 1.12)
  Go version:       go1.13.1
  Git commit:       a872fc2f86
  Built:            Wed Oct  9 02:28:23 2019
  OS/Arch:          linux/amd64
  Experimental:     false
 containerd:
  Version:          v1.3.0.m
  GitCommit:        d50db0a42053864a270f648048f9a8b4f24eced3.m
 runc:
  Version:          1.0.0-rc9
  GitCommit:        d736ef14f0288d6993a1845745d6756cfc9ddd5a
 docker-init:
  Version:          0.18.0
  GitCommit:        fec3683

[luckydonald]

I think that is correct behavior. You excluded it so it doesn't get send to the docker machine.

You could include that file again with
!path/to/Dockerfile if I remember the ignore file syntax correctly.

[kerhong]

@luckydonald I don't think this behavior is correct, because all other ways to ignore Dockerfile that I described can be built.

There is also https://github.com/moby/moby/blob/master/CHANGELOG.md#150-2015-02-10

Dockerfile and .dockerignore files can be themselves excluded as part of the .dockerignore file, thus preventing modifications to these files invalidating ADD or COPY instructions cache

[luckydonald]

Huh, indeed.