Use debian-apt-cacher:buster-slim

Signed-off-by: René Jochum <rene@jochum.dev>

Dockerfile

@@ -1,14 +1,9 @@
-FROM registry.jochum.dev/library/debian:buster-slim
+FROM registry.jochum.dev/jochum/debian-apt-cacher:buster-slim
 
 LABEL maintainer "René Jochum <rene@jochum.dev>"
 
-RUN apt-get install -qy netcat-openbsd && \
-    nc -w1 -z apt-cacher.apt-cacher.svc.cluster.local 3142 1>/dev/null 2>&1 && \
-    echo -e 'Acquire::HTTP::Proxy "http://apt-cacher.apt-cacher.svc.cluster.local:3142";\nAcquire::HTTPS::Proxy "false";' > /etc/apt/apt.conf.d/01proxy
-
 RUN echo "postfix postfix/mailname string mail.example.com" | debconf-set-selections && \
     echo "postfix postfix/main_mailer_type string 'No configuration'" | debconf-set-selections && \
-    sed -i 's/deb.debian.org/ftp.ch.debian.org/g' /etc/apt/sources.list && \
     apt-get update --allow-releaseinfo-change && \
     apt-get install -qy -o 'DPkg::Options::=--force-confold' -o 'DPkg::Options::=--force-confdef' postfix postfix-pgsql postfix-mysql postfix-pcre python3-minimal python3-jinja2