switched to nginx-unprivileged image

Dockerfile

@@ -1,4 +1,4 @@
-FROM nginx:1.17.8-alpine
+FROM nginxinc/nginx-unprivileged:1.17.8-alpine
 LABEL MAINTAINER="BBT Software AG <[email protected]>"
 
 ENV CHK_DOCKER_API_VERSION v1.38
@@ -10,10 +10,15 @@ ENV TZ UTC
 
 COPY index.html /usr/share/nginx/html/index.html
 
+USER root
+RUN chmod 775 /usr/share/nginx/html/
+RUN chown nginx:nginx /usr/share/nginx/html/
 RUN apk add --no-cache bash curl jq && \
     echo $TZ > /etc/timezone
+USER nginx
 
 COPY docker-entrypoint.sh /usr/local/bin/
+
 ENTRYPOINT ["docker-entrypoint.sh"]
 
 EXPOSE 80