Jekyll Dockerfile with intermediate containers, deploying with nginx.

Dockerfile

FROM ruby:2.6 AS jekyll
WORKDIR /usr/src/app
COPY Gemfile Gemfile.lock /usr/src/app/
RUN bundle install --quiet -j 4
COPY . /usr/src/app/
EXPOSE 3000
CMD jekyll server -P 3000 -H 0.0.0.0 -w --force_polling --incremental

FROM jekyll AS website
ENV JEKYLL_ENV=production
RUN jekyll build

FROM nginx AS final
COPY _nginx/default.conf /etc/nginx/conf.d/default.conf

WORKDIR /usr/share/www
COPY --from=website /usr/src/app/docs /usr/share/www/

EXPOSE 5000