What is .build-deps in the following command? I can’t find an explanation in the Alpine docs. Is this a file that is predefined? Is see this referenced in many Dockerfiles.
RUN apk add --no-cache --virtual .build-deps \
gcc \
freetype-dev \
musl-dev
RUN pip install --no-cache-dir <packages_that_require_gcc...> \
RUN apk del .build-deps
