alpine dockerfile example

Dockerfile

# forgive me for any noob stuff, this is like my second dockerfile :P
FROM ruby:2.3-alpine

WORKDIR /app

COPY Gemfile* ./

# the --virtual <name> flag groups packages by name. I use this (sometimes) to remove build deps once everything is installed.
# All bulid stuff in one RUN command to reduce number of image layers
RUN apk update && \
    apk add --no-cache --virtual build-deps ruby-dev build-base git postgresql-dev && \
    apk add --no-cache --virtual run-deps libpq nodejs && \
    gem install bundler --no-ri --no-rdoc && \
    bundle install
    # apk del build-deps # disabled for development so I can go in the container and try stuff

COPY . .

EXPOSE 3000

CMD [ "rails", "s", "-p", "3000", "-b", "0.0.0.0" ]