where to write and save the dockerfile? - r

Question

I am a beginner in docker, my question can be considered somewhat obvious but where do I save and write the dockerfile?
example:
FROM openanalytics/r-base
LABEL maintainer "Tobias Verbeke <tobias.verbeke#openanalytics.eu>"
# system libraries of general use
RUN apt-get update && apt-get install -y \
sudo \
pandoc \
pandoc-citeproc \
libcurl4-gnutls-dev \
libcairo2-dev \
libxt-dev \
libssl-dev \
libssh2-1-dev \
libssl1.0.0
# system library dependency for the euler app
RUN apt-get update && apt-get install -y \
libmpfr-dev
# basic shiny functionality
RUN R -e "install.packages(c('shiny', 'rmarkdown'), repos='https://cloud.r-project.org/')"
# install dependencies of the euler app
RUN R -e "install.packages('Rmpfr', repos='https://cloud.r-project.org/')"
# copy the app to the image
RUN mkdir /root/euler
COPY euler /root/euler
COPY Rprofile.site /usr/lib/R/etc/
EXPOSE 3838
CMD ["R", "-e", "shiny::runApp('/root/euler')"]
where specifically does this file have to be written? Where specifically does he have to be saved? what format does it have to be saved?

Answer 1

The pattern I follow is to include the Dockerfile in the root of the project directory.
I also store it in the same repo as the project.