Dockerfile

FROM ruby:2.3-alpine

# Set local timezone
RUN apk add --update tzdata &&     cp /usr/share/zoneinfo/Europe/London /etc/localtime &&     echo "Europe/London" > /etc/timezone

# Install your app's runtime dependencies in the container
RUN apk add --update --virtual runtime-deps postgresql-client nodejs libffi-dev readline sqlite

# Bundle into the temp directory
WORKDIR /tmp
ADD Gemfile* ./

RUN apk add --virtual build-deps build-base openssl-dev postgresql-dev libc-dev linux-headers libxml2-dev libxslt-dev readline-dev &&     bundle install --jobs=2 &&     apk del build-deps

# Copy the app's code into the container
ENV APP_HOME /app
COPY . $APP_HOME
WORKDIR $APP_HOME

# Configure production environment variables
ENV RAILS_ENV=production     RACK_ENV=production

# Expose port 3000 from the container
EXPOSE 3000

# Run puma server by default
CMD ["bundle", "exec", "puma", "-C", "config/puma.rb"]