Set the owner of the /app/tmp and /tmp volumes in the Dockerfile

AWS ECS documentation [1] shows how volume ownership should be set

[1] https://docs.aws.amazon.com/AmazonECS/latest/developerguide/bind-mounts.html

Author: AP-Hunt

Dockerfile

@@ -37,9 +37,6 @@ COPY --chown=ruby:ruby . .
 
 FROM base AS app
 
-VOLUME "/tmp/"
-VOLUME "/app/tmp/"
-
 ENV RAILS_ENV="${RAILS_ENV:-production}" \
     PATH="${PATH}:/home/ruby/.local/bin" \
     USER="ruby"
@@ -61,6 +58,10 @@ RUN chmod 0755 bin/*
 COPY --chown=ruby:ruby --from=build /usr/local/bundle /usr/local/bundle
 COPY --chown=ruby:ruby --from=build /app /app
 
+RUN mkdir -p "/tmp" "/app/tmp/" && chown ruby:ruby "/tmp" && chown ruby:ruby "/app/tmp/"
+VOLUME "/tmp/"
+VOLUME "/app/tmp/"
+
 EXPOSE 9292
 
 CMD ["/bin/sh", "-o", "xtrace", "-c", "rails s -b 0.0.0.0 -p 9292"]