# Base image
FROM simgrid/stable
-RUN apt update && apt -y upgrade
+# https://stackoverflow.com/questions/35134713/disable-cache-for-specific-run-commands
+ADD "http://deb.debian.org/debian/dists/testing/Release" skipcache
+RUN apt update && apt -y upgrade
RUN apt install -y sudo && \
groupadd -g 999 user && \