Hi, we make heavy use of ONBUILD option in our environment.

Our typical Dockerfile looks like this:

FROM my.company.com/ci/dotnet:v1-build as build
FROM my.company.com/ci/dotnet:v1-runtime

This works fine in legacy docker build, but turning on BUILDKIT option activates some optimizations, so docker tries to build these containers in parallel. The problem is containers are dependent:

1. my.company.com/ci/dotnet:v1-build:

   FROM base:v1
   WORKDIR /src
   ONBUILD COPY . /src
   ONBUILD make clean all

2. my.company.com/ci/dotnet:v1-runtime:

   FROM runtime:v1
   WORKDIR /app
   ONBUILD COPY --from=build /src/target /app

Running DOCKER_BUILDKIT=1 docker build . results in:

DOCKER_BUILDKIT=1 docker build .
[+] Building 0.8s (8/8) FINISHED
...
 => ERROR [stage-2 3/1] COPY --from=build /src/target/ /app 0.0s
------
 > [stage-2 3/1] COPY --from=build /src/target/ /app:
------
 not found: not found

My questions are:

1. Can I turn off these optimizations to run builds sequentially?
2. Is there a way to mark these stages as dependent explicitly?