add wrapper script

Dockerfile

@@ -9,6 +9,8 @@ LABEL maintainer="Robert Kaussow <mail@geeklabor.de>" \
 ARG BUILD_VERSION
 ENV VALIDATOR_VERSION="${BUILD_VERSION:-20.6.30}"
 
+ADD overlay/ /
+
 RUN apk add --update --no-cache --virtual .build-deps libarchive-tools curl && \
     apk --update add openjdk8 && \
     mkdir -p /var/www/app && \
@@ -25,4 +27,4 @@ WORKDIR /var/www/app
 
 USER root
 CMD []
-ENTRYPOINT ["java", "-jar", "/var/www/app/vnu.jar"]
+ENTRYPOINT ["/bin/vnu"]

overlay/bin/vnu

@@ -0,0 +1,4 @@
+#!/usr/bin/env sh
+set -eo pipefail
+
+exec java -jar /var/www/app/vnu.jar "$@"