Simplified the script by adding Runitor

dnsupdater/Dockerfile

@@ -1,8 +1,20 @@
+FROM alpine:latest AS builder
+
+ARG TARGETPLATFORM
+
+RUN DOWNLOAD_ARCH=$(echo ${TARGETPLATFORM} | cut -d"/" -f 2) \
+	&& apk add --no-cache curl \
+	&& DOWNLOAD_URL=$(curl -s https://api.github.com/repos/bdd/runitor/releases/latest | grep "browser_download_url" | grep "linux-"${DOWNLOAD_ARCH} | cut -d\" -f4) \
+	&& curl --retry 3 -L -s -o runitor ${DOWNLOAD_URL} \
+	&& chmod +x runitor
+
 FROM alpine:latest
 
-ADD dnsupdater.sh /usr/bin/dnsupdater.sh
+COPY --from=builder runitor /usr/bin/
+
+ADD dnsupdater.sh docker-command.sh /usr/bin/
 
 RUN apk add --no-cache bash curl jq bind-tools \
 	&& chmod +x /usr/bin/dnsupdater.sh
 
-CMD /usr/bin/dnsupdater.sh
+CMD ["/usr/bin/docker-command.sh"]