FROM alpine:3.15

RUN sed -i 's/dl-cdn.alpinelinux.org/mirrors.ustc.edu.cn/g' /etc/apk/repositories  \
    && apk add opendkim opendkim-utils \
    && chown opendkim:opendkim -R /etc/opendkim/ \
    && chmod -R 700 /etc/opendkim \
    && rm -rf /var/cache/apk/* 

EXPOSE 8891

CMD ["/usr/sbin/opendkim", "-f"]