Set RUBOCOP_CACHE_ROOT + install NodeJS the Rails Way

Dockerfile

@@ -7,13 +7,22 @@ RUN apt-get update && apt-get install -y locales \
     && rm -rf /var/lib/apt/lists/*
 ENV LANG en_US.utf8
 
+# Node
+ARG NODE_VERSION=14.21.3
+ENV PATH=/usr/local/node/bin:$PATH
+RUN curl -sL https://github.com/nodenv/node-build/archive/master.tar.gz | tar xz -C /tmp/ && \
+    /tmp/node-build-master/bin/node-build "${NODE_VERSION}" /usr/local/node && rm -rf /tmp/node-build-master
+
 # Binary dependencies for SQLite
 RUN apt-get update && apt-get install -y sqlite3 libsqlite3-dev curl gnupg \
     && rm -rf /var/lib/apt/lists/*
 ENV FULLSTACK_FOLDER /workspace
+ENV RUBOCOP_CACHE_ROOT /workspace
 WORKDIR $FULLSTACK_FOLDER
-RUN curl -sL https://deb.nodesource.com/setup_14.x  | bash -
-RUN apt-get -y install nodejs
 
 COPY Gemfile $FULLSTACK_FOLDER/Gemfile
 RUN ["bundle", "install"]
+
+# Run and own only the runtime files as a non-root user for security
+RUN useradd ruby --create-home --shell /bin/bash && chown -R ruby:ruby $FULLSTACK_FOLDER
+USER ruby:ruby