Use hard-coded (local) tomcat sha512 fingerprint

dockerfiles/Dockerfile.dspace

@@ -9,6 +9,8 @@ ARG LABEL_VERSION
 ARG LABEL_BUILD_DATE
 ARG LABEL_VCS_URL="https://gitlab.inf.unibz.it/commul/docker/clarin-dspace"
 ARG TOMCAT_VERSION="8.0.53"
+ARG TOMCAT_SHA512="cd8a4e48a629a2f2bb4ce6b101ebcce41da52b506064396ec1b2915c0b0d8d82123091242f2929a649bcd8b65ecf6cd1ab9c7d90ac0e261821097ab6fbe22df9 *apache-tomcat-8.0.53.tar.gz"
+# https://archive.apache.org/dist/tomcat/tomcat-8/v8.0.53/bin/apache-tomcat-8.0.53.tar.gz.sha512
 
 LABEL maintainer="Alexander König <Alexander.Koenig@eurac.edu>" \
       maintainer="Egon W. Stemle <egon.stemle@eurac.edu>" \
@@ -58,13 +60,12 @@ ENV LANGUAGE=en_US.UTF-8
 #
 # build tomcat $TOMCAT_VERSION (> 8.0.35), version recommended by LINDAT
 RUN wget -O /tmp/apache-tomcat-$TOMCAT_VERSION.tar.gz \
-        https://archive.apache.org/dist/tomcat/tomcat-8/v$TOMCAT_VERSION/bin/apache-tomcat-$TOMCAT_VERSION.tar.gz && \
-    wget -O /tmp/apache-tomcat-$TOMCAT_VERSION.tar.gz.sha512 \
-        https://archive.apache.org/dist/tomcat/tomcat-8/v$TOMCAT_VERSION/bin/apache-tomcat-$TOMCAT_VERSION.tar.gz.sha512
+        https://archive.apache.org/dist/tomcat/tomcat-8/v$TOMCAT_VERSION/bin/apache-tomcat-$TOMCAT_VERSION.tar.gz
 WORKDIR /tmp
 
 # checksum check the download
-RUN sha512sum --check apache-tomcat-$TOMCAT_VERSION.tar.gz.sha512
+RUN echo "$TOMCAT_SHA512" > /tmp/apache-tomcat.sha512 && \
+    sha512sum --check apache-tomcat.sha512
 
 RUN mkdir /opt/tomcat8 && \
     tar xzf /tmp/apache-tomcat-$TOMCAT_VERSION.tar.gz \