feat(docker-stack): add archmirror stack

docker/stacks/archmirror/rsync/Dockerfile

@@ -0,0 +1,24 @@
+FROM alpine:latest AS builder
+
+RUN apk add --no-cache curl \
+    && curl -fsSLO https://github.com/aptible/supercronic/releases/download/v0.2.29/supercronic-linux-amd64 \
+    && echo "cd48d45c4b10f3f0bfdd3a57d054cd05ac96812b  supercronic-linux-amd64" | sha1sum -c - \
+    && chmod +x supercronic-linux-amd64
+
+FROM alpine:latest
+
+RUN apk add --no-cache rsync flock \
+    && rm -rf /var/cache/apk/*
+
+COPY --from=builder /supercronic-linux-amd64 /usr/local/bin/supercronic
+
+RUN mkdir -p /archlinux /var/log /var/lock
+
+COPY sync.sh /usr/local/bin/sync.sh
+COPY crontab /etc/crontab
+
+RUN chmod +x /usr/local/bin/sync.sh
+
+WORKDIR /archlinux
+
+CMD ["supercronic", "/etc/crontab"]