Dockerfile ONBUILD

# First stage
FROM debian as base
ENV VAR_ENV=env_value
ARG VAR_ARG=arg_value
ONBUILD ENV VAR_ENV_ONBUILD=onbuild_env_value
ONBUILD ARG VAR_ARG_ONBUILD=onbuild_arg_value
RUN echo "First stage build time:"; env | grep VAR_
# Second stage
FROM base
RUN echo "Second stage build time:"; env | grep VAR_
# Third stage
FROM base
RUN echo "Third stage build time:"; env | grep VAR_
CMD ["bash", "-c", "echo At runtime; env | grep VAR_"]