${} dockerfile code example

Example 1: dockerfile example

FROM ubuntu:18.04
COPY . /app
RUN make /app
CMD python /app/app.py

Example 2: dockerfile env variabes

FROM busybox
ENV foo /bar
WORKDIR ${foo}   # WORKDIR /bar
ADD . $foo       # ADD . /bar
COPY \$foo /quux # COPY $foo /quux