Dockerfile
FROM scratch
# nobody / nogroup
ARG DNSBL_USER=65534
ARG DNSBL_GROUP=65534
USER $DNSBL_USER:$DNSBL_GROUP
ENV DNSBL_EXP_RESOLVER=ubound:53
ENV DNSBL_EXP_RBLS=/rbls.ini
ENV DNSBL_EXP_TARGETS=/targets.ini
COPY dnsbl-exporter rbls.ini targets.ini /
EXPOSE 9211
ENTRYPOINT ["/dnsbl-exporter"]