After upgrade to 24.0.0 (and factory reset) docker build is now case sensitive - needs 'Dockerfile' errors with 'dockerfile'

[allanbarklie]

• I have tried with the latest version of my channel (Stable or Edge)
• I have uploaded Diagnostics
• Diagnostics ID: 80BF7F34-05E5-4A73-8CBA-640A107F6666/20201001120231

Expected behavior

Docker image is built using either a file called 'Dockerfile' or 'dockerfile' when a command is typed as:
docker build .

Actual behavior

Docker build command returns an error if the dockerfile is called 'dockerfile' e.g.
failed to solve with frontend dockerfile.v0: failed to read dockerfile: open /var/lib/docker/tmp/buildkit-mount825383798/Dockerfile: no such file or directory

Workaround:
docker build -f dockerfile .

Information

• Windows Version: 10.0.19041 Build 19041

• Docker Desktop Version: 24.0.0

• Are you running inside a virtualized Windows e.g. on a cloud server or on a mac VM: No

• Is it reproducible? Yes

• Is the problem new? yes

• Did the problem appear with an update? Yes 24.0.0

• A reproducible case if this is a bug, Dockerfiles with reproduction inside is best.
  Any dockerfile using the name 'dockerfile' all lower case

Steps to reproduce the behavior

1. name a dockerfile 'dockerfile' all lower case
2. try and build with: docker build .
3. get an error like
   failed to solve with frontend dockerfile.v0: failed to read dockerfile: open /var/lib/docker/tmp/buildkit-mount582525092/Dockerfile: no such file or directory
4. try instead with: docker build -f dockerfile .
5. watch it succeed

I found this old issue:
moby/moby#10807

[allanbarklie]

I'm not sure what the intended behaviour is but this is a an undocumented change in behaviour.
In our own use case we will just rename our dockerfiles to 'Dockerfile'.
I thought it would be useful to have this change captured in a defect - even if it ends up being just to document it for others getting the error.

[stephen-turner]

Thanks for the report, @allanbarklie, but I wonder if I could ask you to file it in moby/moby? The command line tools are just an upstream for us, which we bundle. Sorry, I would just move the ticket but I can't because the target is not in the docker org.

[allanbarklie]

@stephen-turner Thanks for taking the time to look at this . I'd like to confirm, your releases notes say Docker Desktop now enables BuildKit by default after a reset to factory defaults. To revert to the old docker build experience, go to Preferences > Docker Engine and then disable the BuildKit feature.
As this directly references a change to the tech. used to provide docker build functionality, I'd like to check if this change affects what dependency the change should be reported to?

[stephen-turner]

@allanbarklie Actually, that's a good point. You can check whether that's the cause by changing back to the old build in the way described. If it is in buildx but not legacy build, I can move this ticket to docker/buildx.

[allanbarklie]

@stephen-turner thanks - I can confirm that the problem occurs with
"features": {
"buildkit": true
}

and does not occur with

"features": {
"buildkit": false
}

[stephen-turner]

Great, thanks, so I guess buildkit has regressed the earlier fix you mentioned in moby/moby#10807.
I'll reopen the ticket and move it into the buildkit repo.

[crazy-max]

Fixed by #444