When passing a Dockerfile through stdin, it's not possible to specify the
name of the Dockerfile (using the `-f` option). When building with BuildKit
enabled, an error is already produced for this case, but the classic builder
silently ignored it.
This patch adds an error for this situation:
echo -e 'FROM busybox' | DOCKER_BUILDKIT=0 docker build -f some.Dockerfile -
DEPRECATED: The legacy builder is deprecated and will be removed in a future release.
BuildKit is currently disabled; enable it by removing the DOCKER_BUILDKIT=0
environment-variable.
unable to prepare context: ambiguous Dockerfile source: both stdin and flag correspond to Dockerfiles
Signed-off-by: Sebastiaan van Stijn <github@gone.nl>
c2535aa467