Behaviour

Steps to reproduce this issue

1. Use the build-push-action with choosing a subdirectory from git context.
2. Recognise the warning about the BuildKit version, but without finding any reference to build kit, leave it where it is.

Expected behaviour

The build runs, and the correct BuildKit is chosen.

Actual behaviour

The error message "subdirectories are not yet supported" is thrown.

Mitigation

The warning is a little passive aggressive, as it does state the problem, but no solution. Following the suggested requirements of the action, the expected behaviour can be achieved when using the setup-buildx-action. For a new user of GitHub actions, like me, it is not obvious that this action will bring the correct BuildKit version >0.9, as required by the warning.

Some written help in finding this little additional setting to be made when wanting to use subdirectories would be very much appreciated.