Improve docker compose performance (#347) 🤩

* Fix warning Integrity check: System parameters don't match

* Reduce commands required to use docker-compose and update quick-setup doc

Data will still persist when stopping and restarting containers.
To destroy the data can use docker-compose down --volumes

* Moved webpacker-dev-server to its own service

* cache bundle and yarn - improve volume performance - env conditional statements

* Fix inconsistent build results found during testing

docker/Dockerfile

@@ -1,5 +1,16 @@
 FROM ruby:2.6.5-slim
 
+# ARG default to production settings
+# For development docker-compose file overrides ARGS
+ARG BUNDLE_WITHOUT="development:test"
+ENV BUNDLE_WITHOUT ${BUNDLE_WITHOUT}
+
+ARG RAILS_SERVE_STATIC_FILES=true
+ENV RAILS_SERVE_STATIC_FILES ${RAILS_SERVE_STATIC_FILES}
+
+ARG RAILS_ENV=production
+ENV RAILS_ENV ${RAILS_ENV}
+
 RUN apt-get update \
     && apt-get -qq -y install \
     build-essential \
@@ -18,13 +29,24 @@ RUN apt-get update \
 
 RUN mkdir -p /app
 WORKDIR /app
+
+COPY Gemfile Gemfile.lock ./
+
+# Do not install development or test gems in production
+RUN if [ "$RAILS_ENV" = "production" ]; then \
+  bundle install -j 4 -r 3 --without development test; \
+  else bundle install -j 4 -r 3; \
+  fi
+
+COPY package.json yarn.lock ./
+RUN yarn install
+
 COPY . /app
 
-ENV RAILS_SERVE_STATIC_FILES true
-ENV RAILS_ENV=production
-
-RUN bundle
-RUN SECRET_KEY_BASE=precompile_placeholder bundle exec rake assets:precompile
+# generate production assets if production environment
+RUN if [ "$RAILS_ENV" = "production" ]; then \
+  SECRET_KEY_BASE=precompile_placeholder bundle exec rake assets:precompile; \
+  fi
 
 # Add a script to be executed every time the container starts.
 COPY ./docker/entrypoint.sh /usr/bin/

docker/Procfile.docker.dev

@@ -1,2 +0,0 @@
-backend: ../bin/rails server -b 0.0.0.0 -p 3000
-frontend: ../bin/webpack-dev-server

docker/entrypoint.sh

@@ -5,4 +5,4 @@ set -e
 rm -f /app/tmp/pids/server.pid
 
 # Then exec the container's main process (what's set as CMD in the Dockerfile).
-exec "$@"
+exec "$@"