Dockerfile template for Rails app

Dockerfile

# Change Ruby version accordingly
FROM ruby:2.3-stretch
LABEL maintainer="carloshrsouza@gmail.com"

RUN apt-get update
RUN apt-get install -y git

RUN mkdir /myapp
WORKDIR /myapp

COPY Gemfile /myapp/Gemfile
COPY Gemfile.lock /myapp/Gemfile.lock

RUN bundle install

# This is a quick fix for a known issue
# where a value written to server.pid will
# prevent the server from being started.
COPY entrypoint.sh /usr/bin/
RUN chmod +x /usr/bin/entrypoint.sh

ENTRYPOINT ["entrypoint.sh"]
CMD ["rails", "server", "-b", "0.0.0.0"]

entrypoint.sh

#!/bin/bash
set -e

# Remove a potentially pre-existing server.pid for Rails.
rm -f /myapp/tmp/pids/server.pid

# Then exec the container's main process (what's set as CMD in the Dockerfile).
exec "$@"