feat: add nonroot user, update permissions and remove unrequired files in Dockerfile

Dockerfile

@@ -2,10 +2,10 @@ FROM ruby:3.1.4-alpine3.18 as base
 
 WORKDIR /app
 
-# Add the timezone as it’s not configured by default in Alpine
+# Add the timezone as it's not configured by default in Alpine
 RUN apk add --update --no-cache tzdata && \
-  cp /usr/share/zoneinfo/Europe/London /etc/localtime && \
+    cp /usr/share/zoneinfo/Europe/London /etc/localtime && \
-  echo "Europe/London" > /etc/timezone
+    echo "Europe/London" > /etc/timezone
 
 # build-base: compilation tools for bundle
 # yarn: node package manager
@@ -27,9 +27,15 @@ COPY . /app/
 RUN bundle exec rake assets:precompile
 
 ENV PORT=8080
-
 EXPOSE ${PORT}
 
+RUN adduser --system --no-create-home nonroot
+
+# We expect the rake assets:precompile command to create these directories, but mkdir -p will create them if they don't already exist
+RUN mkdir -p tmp log
+RUN chown -R nonroot tmp log
+RUN chown nonroot db/schema.rb
+
 FROM base as development
 
 RUN bundle config set without ""
@@ -38,10 +44,12 @@ RUN bundle install --jobs=4 --no-binstubs --no-cache
 # Install gecko driver for Capybara tests
 RUN apk add firefox
 RUN wget https://github.com/mozilla/geckodriver/releases/download/v0.31.0/geckodriver-v0.31.0-linux64.tar.gz \
-  && tar -xvzf geckodriver-v0.31.0-linux64.tar.gz \
+    && tar -xvzf geckodriver-v0.31.0-linux64.tar.gz \
-  && rm geckodriver-v0.31.0-linux64.tar.gz \
+    && rm geckodriver-v0.31.0-linux64.tar.gz \
-  && chmod +x geckodriver \
+    && chmod +x geckodriver \
-  && mv geckodriver /usr/local/bin/
+    && mv geckodriver /usr/local/bin/
+
+USER nonroot
 
 CMD bundle exec rails s -e ${RAILS_ENV} -p ${PORT} --binding=0.0.0.0
 
@@ -50,8 +58,32 @@ FROM base as staging
 RUN bundle config set without "development"
 RUN bundle install --jobs=4 --no-binstubs --no-cache
 
+# Cleanup to reduce image size
+RUN rm -rf node_modules && \
+    rm -rf /usr/local/bundle/cache && \
+    find /usr/local/bundle/gems -name "*.c" -delete && \
+    find /usr/local/bundle/gems -name "*.h" -delete && \
+    find /usr/local/bundle/gems -name "*.o" -delete && \
+    find /usr/local/bundle/gems -name "*.html" -delete && \
+    rm -rf .env  && \
+    rm -rf frontend
+
+USER nonroot
+
 CMD bundle exec rails s -e ${RAILS_ENV} -p ${PORT} --binding=0.0.0.0
 
 FROM base as production
 
+# Cleanup to reduce image size
+RUN rm -rf node_modules && \
+    rm -rf /usr/local/bundle/cache && \
+    find /usr/local/bundle/gems -name "*.c" -delete && \
+    find /usr/local/bundle/gems -name "*.h" -delete && \
+    find /usr/local/bundle/gems -name "*.o" -delete && \
+    find /usr/local/bundle/gems -name "*.html" -delete && \
+    rm -rf .env  && \
+    rm -rf frontend
+
+USER nonroot
+
 CMD bundle exec rails s -e ${RAILS_ENV} -p ${PORT} --binding=0.0.0.0