From a77d9834d867b44a7f10d1481916498332c586ff Mon Sep 17 00:00:00 2001
From: Miek Gieben <miek@miek.nl>
Date: Mon, 4 Jun 2018 19:20:21 +0100
Subject: [PATCH] Docker: drop alpine (#1843)

* Docker: drop alpine

Create a multistage docker build image that uses debian to install certs
and then create the final image by using FROM: scratch. This creates a
(slightly) smaller images and drops busybox and alpine.

* Even less copying
---
 Dockerfile | 9 ++++++---
 1 file changed, 6 insertions(+), 3 deletions(-)

diff --git a/Dockerfile b/Dockerfile
index d732c1daf..9c4608589 100644
--- a/Dockerfile
+++ b/Dockerfile
@@ -1,8 +1,11 @@
-FROM alpine:latest
+FROM debian:stable-slim
 
-# Only need ca-certificates & openssl if want to use DNS over TLS (RFC 7858).
-RUN apk --no-cache add bind-tools ca-certificates openssl && update-ca-certificates
+RUN apt-get update && apt-get -uy upgrade
+RUN apt-get -y install ca-certificates && update-ca-certificates
 
+FROM scratch
+
+COPY --from=0 /etc/ssl/certs /etc/ssl/certs
 ADD coredns /coredns
 
 EXPOSE 53 53/udp