FROM golang as builder
WORKDIR /tmp/dnsupdater
COPY . .
RUN go get .
RUN CGO_ENABLED=0 GOOS=linux go build -a -installsuffix cgo -o dnsupdater .

FROM busybox:glibc
COPY --from=builder /etc/ssl/certs/ca-certificates.crt /etc/ssl/certs/ca-certificates.crt
COPY --from=builder /usr/share/zoneinfo /usr/share/zoneinfo
COPY --from=builder /tmp/dnsupdater/dnsupdater .

RUN mkdir -p /var/spool/cron/crontabs /var/log
COPY entry.sh /entry.sh
RUN touch /var/log/cron.log
WORKDIR "/"
ENTRYPOINT ["/entry.sh"]