message: let the mysql-slow.log be writable
diff: @@ -116,6 +116,7 @@ COPY root/usr/share/container-scripts/mysql/galera.cnf /usr/share/container-scri
  COPY root/usr/share/container-scripts/mysql/configure-galera.sh /usr/share/container-scripts/mysql/configure-galera.sh
  RUN /bin/fix-permissions /usr/share/container-scripts/mysql/
  +RUN touch /var/log/mysql-slow.log && /bin/fix-permissions /var/log/mysql-slow.log
  ### we cannot start mysql as root, we add the user mysql to the group root and change the user of the Docker Image to this user
  RUN addgroup mysql root
  