Install update-dns.sh in the Image and add a cronjob

Dockerfile

@@ -8,7 +8,16 @@ RUN apk -v --update add \
         less \
         mailcap \
         jq \
+        cron \
         && \
     pip install --upgrade awscli==1.14.5 s3cmd==2.0.1 python-magic && \
     apk -v --purge del py-pip && \
-    rm /var/cache/apk/*
+    rm /var/cache/apk/*
+
+COPY ./update-dns.sh /usr/local/bin/
+RUN chmod +x /usr/local/bin/update-dns.sh
+
+RUN echo -e "*/10 * * * * update-dns.sh > /proc/1/fd/1 2>/proc/1/fd/2\n" > /etc/cron.d/dns-cron
+RUN crontab /etc/cron.d/dns-cron
+
+CMD ["cron", "-f"]