dockerized go-apt-cacher with config for internal use

Dockerfile

@@ -1,3 +1,23 @@
-FROM ubuntu:focal
+FROM golang:1.15-buster AS builder
 
+WORKDIR /usr/local/src
+#RUN apt update && apt install -y git
 
+RUN git clone https://github.com/cybozu-go/aptutil.git && \
+    cd aptutil && \
+    git checkout 3f82d83844818cdd6a6d7dca3eca0f76d8a3fce5
+
+WORKDIR /usr/local/src/aptutil
+RUN go mod download
+WORKDIR /usr/local/src/aptutil/cmd/go-apt-cacher
+RUN go build
+RUN find .
+
+FROM debian:buster-slim AS final
+COPY --from=builder /usr/local/src/aptutil/cmd/go-apt-cacher/go-apt-cacher /usr/local/bin/go-apt-cacher
+ADD ./go-apt-cacher.toml /etc/go-apt-cacher.toml
+RUN chmod ugoa+rx /usr/local/bin/* && \
+    mkdir -p /var/spool/go-apt-cacher && \
+    chown nobody:nogroup /var/spool/go-apt-cacher
+USER nobody:nogroup
+ENTRYPOINT ["/usr/local/bin/go-apt-cacher"]