From cb41a91a65c865ca2c83e5a19ef5d17cdb15f84e Mon Sep 17 00:00:00 2001
From: YAEGASHI Takeshi <yaegashi@debian.org>
Date: Tue, 22 Jan 2019 02:50:50 +0900
Subject: [PATCH] Docker build optimization

Update Dockefile to get a much smaller footprint with alpine image.

Optimize ordering of build steps to avoid needless downloads.

Include CA certificates needed for practical use.
---
 Dockerfile | 20 ++++++++++++--------
 1 file changed, 12 insertions(+), 8 deletions(-)

diff --git a/Dockerfile b/Dockerfile
index c3137f5..487d29b 100644
--- a/Dockerfile
+++ b/Dockerfile
@@ -1,18 +1,22 @@
 FROM golang:1.11-stretch AS builder
-WORKDIR /go/src/github.com/pusher/oauth2_proxy
+
+# Download tools
+RUN wget -O $GOPATH/bin/dep https://github.com/golang/dep/releases/download/v0.5.0/dep-linux-amd64
+RUN chmod +x $GOPATH/bin/dep
+
+# Copy sources
+WORKDIR $GOPATH/src/github.com/pusher/oauth2_proxy
 COPY . .
 
 # Fetch dependencies
-RUN wget -O dep https://github.com/golang/dep/releases/download/v0.5.0/dep-linux-amd64
-RUN chmod +x dep
-RUN mv dep $GOPATH/bin/dep
 RUN dep ensure --vendor-only
 
-# Build image
-RUN ./configure && make clean oauth2_proxy
+# Build binary
+RUN ./configure && make build
 
-# Copy binary to debian
-FROM debian:stretch
+# Copy binary to alpine
+FROM alpine:3.8
+RUN apk add --no-cache ca-certificates
 COPY --from=builder /go/src/github.com/pusher/oauth2_proxy/oauth2_proxy /bin/oauth2_proxy
 
 ENTRYPOINT ["/bin/oauth2_proxy"]