FROM debian:stable-slim

RUN sed -i 's/deb.debian.org/mirrors.ustc.edu.cn/g' /etc/apt/sources.list \
    && apt-get update && apt-get -uy upgrade
RUN apt-get -y install ca-certificates && update-ca-certificates

FROM scratch

COPY --from=0 /etc/ssl/certs /etc/ssl/certs
ADD coredns /coredns

EXPOSE 53 53/udp
ENTRYPOINT ["/coredns"]