guard RLS_ARCH and push the filename intra-step

Author: patricklodder

1.14.4/x86_64-bionic/Dockerfile

@@ -6,16 +6,18 @@ WORKDIR /verify
 ARG RLS_VERSION=1.14.4
 ARG RLS_OS=linux
 ARG RLS_LIB=gnu
-ARG RLS_ARCH=x86_64
+ARG RLS_ARCH=
 
 # Automatically detect architecture
-RUN set -ex && ARCHITECTURE=$(dpkg --print-architecture) && \
-    if [ "${ARCHITECTURE}" = "amd64" ]; then RLS_ARCH=x86_64 ; fi \
+RUN set -ex && ARCHITECTURE=$(dpkg --print-architecture) \
+    && if [ "${ARCHITECTURE}" = "amd64" ]; then RLS_ARCH=x86_64 ; fi \
     && if [ "${ARCHITECTURE}" = "arm64" ]; then RLS_ARCH=aarch64; fi \
     && if [ "${ARCHITECTURE}" = "armhf" ]; then RLS_ARCH=arm && RLS_LIB=gnuabihf; fi \
-    && if [ "${ARCHITECTURE}" = "i386" ]; then RLS_ARCH=i686-pc; fi
+    && if [ "${ARCHITECTURE}" = "i386" ]; then RLS_ARCH=i686-pc; fi \
+    && if [ "${RLS_ARCH}" = "" ]; then echo "Could not determine architecture"; exit 1; fi \
+    && RLS_FILE_NAME=dogecoin-${RLS_VERSION}-${RLS_ARCH}-${RLS_OS}-${RLS_LIB}.tar.gz \
+    && echo -n ${RLS_FILE_NAME} > .filename
 
-ARG RLS_FILE_NAME=dogecoin-${RLS_VERSION}-${RLS_ARCH}-${RLS_OS}-${RLS_LIB}.tar.gz
 ARG SIG_PATH=${RLS_VERSION}-${RLS_OS}
 ARG DESCRIPTOR_PATH=dogecoin/contrib/gitian-descriptors/gitian-${RLS_OS}.yml
 
@@ -39,7 +41,8 @@ RUN git clone --depth 1 ${REPO_GITIAN_BUILDER} gitian && \
     find dogecoin/contrib/gitian-keys -name "*.pgp" |xargs -n 1 gpg --import
 
 # download release binary and verify against random signer
-RUN wget ${RLS_LOCATION}/${RLS_FILE_NAME} && \
+RUN RLS_FILE_NAME=`cat .filename` && \
+    wget ${RLS_LOCATION}/${RLS_FILE_NAME} && \
     gitian/bin/gverify --no-markup -d sigs -r ${SIG_PATH} \
       ${DESCRIPTOR_PATH} | grep OK | \
       shuf -n 1 | sed s/:.*// > random_signer.txt && \