FROM debian:stretch

# procps is for debugging purpose only
RUN apt-get update \
        && apt-get install -y --no-install-recommends rsyslog procps \
        && rm -rf /var/lib/apt/lists/*

# Enable UDP syslog reception
RUN sed -i 's/^#\(module(load="imudp")\)/\1/; s/^#\(input(type="imudp" port="514")\)/\1/' /etc/rsyslog.conf

# Disable kernel logging support
RUN sed -i 's/^module(load="imklog")/#&/' /etc/rsyslog.conf

VOLUME /var/log/
EXPOSE 514/udp

CMD /usr/sbin/rsyslogd -n