Add IMAGE arg for building branch

serve/ru/Dockerfile

 ARG ENV_NAME=env
+ARG IMAGE=gitlab.ssec.wisc.edu:5555/cris_l1b/user/feat-serve-ru:latest
 
 FROM condaforge/mambaforge:4.11.0-0 as environment
 RUN apt-get update
@@ -12,7 +13,7 @@ RUN conda-pack -n ${ENV_NAME} -o /${ENV_NAME}.tar &&\
 
 RUN mamba install -y -p /${ENV_NAME} --strict-channel-priority -c conda-forge python=3.8 flask markdown
 
-FROM gitlab.ssec.wisc.edu:5555/cris_l1b/user/develop
+FROM ${IMAGE}
 ARG ENV_NAME
 ENV ENV_NAME=$ENV_NAME
 COPY --from=environment /$ENV_NAME /$ENV_NAME
@@ -25,5 +26,5 @@ COPY ru_server.py /app/ru_server.py
 COPY README.md /README.md
 
 WORKDIR /app
-#RUN chmod a+xwr /
 CMD ["python", "ru_server.py"]
+ENV saveTotalRU_FLAG=1