export MRAN for use in R

tidyverse/3.3.2/Dockerfile

@@ -15,6 +15,7 @@ RUN apt-get update -qq && apt-get -y --no-install-recommends install \
   && [ -z "$BUILD_DATE" ] && BUILD_DATE=$(date -I --date='TZ="America/Los_Angeles"') || true \
   && MRAN=https://mran.microsoft.com/snapshot/${BUILD_DATE} \
   && echo MRAN=$MRAN >> /etc/environment \
+  && export MRAN=$MRAN \
   && Rscript -e "install.packages(c('littler', 'docopt'), repo = '$MRAN')" \
   && ln -s /usr/local/lib/R/site-library/littler/examples/install2.r /usr/local/bin/install2.r \
   && ln -s /usr/local/lib/R/site-library/littler/bin/r /usr/local/bin/r \

tidyverse/Dockerfile

@@ -14,6 +14,7 @@ RUN apt-get update -qq && apt-get -y --no-install-recommends install \
   && [ -z "$BUILD_DATE" ] && BUILD_DATE=$(date -I --date='TZ="America/Los_Angeles"') || true \
   && MRAN=https://mran.microsoft.com/snapshot/${BUILD_DATE} \
   && echo MRAN=$MRAN >> /etc/environment \
+  && export MRAN=$MRAN \
   && Rscript -e "install.packages(c('littler', 'docopt'), repo = '$MRAN')" \
   && ln -s /usr/local/lib/R/site-library/littler/examples/install2.r /usr/local/bin/install2.r \
   && ln -s /usr/local/lib/R/site-library/littler/bin/r /usr/local/bin/r \