From ed3ccc9573ef199461275ee2613c546bda3ef901 Mon Sep 17 00:00:00 2001
From: Sameer Naik <sameer@damagehead.com>
Date: Fri, 13 Jul 2018 08:39:38 +0530
Subject: [PATCH] optimize image size with multistage builds

---
 Dockerfile | 21 ++++++++++++++++-----
 1 file changed, 16 insertions(+), 5 deletions(-)

diff --git a/Dockerfile b/Dockerfile
index 4a1851f..481a2a2 100644
--- a/Dockerfile
+++ b/Dockerfile
@@ -1,4 +1,12 @@
+FROM ubuntu:bionic-20180526 AS add-apt-repositories
+
+RUN apt-get update \
+ && DEBIAN_FRONTEND=noninteractive apt-get install -y gnupg \
+ && apt-key adv --fetch-keys http://www.webmin.com/jcameron-key.asc \
+ && echo "deb http://download.webmin.com/download/repository sarge contrib" >> /etc/apt/sources.list
+
 FROM ubuntu:bionic-20180526
+
 LABEL maintainer="sameer@damagehead.com"
 
 ENV BIND_USER=bind \
@@ -6,11 +14,11 @@ ENV BIND_USER=bind \
     WEBMIN_VERSION=1.8 \
     DATA_DIR=/data
 
-RUN apt-get update \
- && DEBIAN_FRONTEND=noninteractive apt-get install -y gnupg \
- && apt-key adv --fetch-keys http://www.webmin.com/jcameron-key.asc \
- && echo "deb http://download.webmin.com/download/repository sarge contrib" >> /etc/apt/sources.list \
- && rm -rf /etc/apt/apt.conf.d/docker-gzip-indexes \
+COPY --from=add-apt-repositories /etc/apt/trusted.gpg /etc/apt/trusted.gpg
+
+COPY --from=add-apt-repositories /etc/apt/sources.list /etc/apt/sources.list
+
+RUN rm -rf /etc/apt/apt.conf.d/docker-gzip-indexes \
  && apt-get update \
  && DEBIAN_FRONTEND=noninteractive apt-get install -y \
       bind9=1:${BIND_VERSION}* bind9-host=1:${BIND_VERSION}* dnsutils \
@@ -18,8 +26,11 @@ RUN apt-get update \
  && rm -rf /var/lib/apt/lists/*
 
 COPY entrypoint.sh /sbin/entrypoint.sh
+
 RUN chmod 755 /sbin/entrypoint.sh
 
 EXPOSE 53/udp 53/tcp 10000/tcp
+
 ENTRYPOINT ["/sbin/entrypoint.sh"]
+
 CMD ["/usr/sbin/named"]