add Dockerfile and docker-compose.yml

Dockerfile

@@ -0,0 +1,30 @@
+FROM ruby:2.5
+
+# Install app dependencies.
+RUN apt-get update -qq && apt-get install -y build-essential libpq-dev nodejs 
+
+# Set an environment variable for the install location.
+ENV RAILS_ROOT /usr/src/app
+
+# Make the directory and set as working.
+RUN mkdir -p $RAILS_ROOT
+WORKDIR $RAILS_ROOT
+
+# Set environment variables.
+ENV RAILS_ENV production
+
+# Adding project files.
+COPY . .
+
+# Install gems.
+RUN bundle install --without development test --deployment --clean
+
+# Precompile assets.
+RUN bundle exec rake assets:clean
+RUN bundle exec rake assets:precompile
+
+# Expose port 3000.
+EXPOSE 3000
+
+# Start the application.
+CMD ["bin/start"]