make docker image smaller

prod/Dockerfile

@@ -1,4 +1,4 @@
-FROM alpine:3.6
+FROM alpine:3.7
 
 LABEL com.github.pottava.application="aws-s3-proxy" \
       com.github.pottava.usage="docker run -d -p 8080:80 -e AWS_S3_BUCKET pottava/s3-proxy" \
@@ -9,31 +9,17 @@ ENV AWS_REGION=us-east-1 \
 
 RUN apk add --no-cache ca-certificates
 
-RUN apk --no-cache add --virtual build-dependencies bash gcc musl-dev openssl go git \
-
-    # Install go 1.9
-    && GOLANG_VERSION=1.9.1 \
-    && GOLANG_SRC_URL=https://golang.org/dl/go$GOLANG_VERSION.src.tar.gz \
-    && GOLANG_SRC_SHA256=a84afc9dc7d64fe0fa84d4d735e2ece23831a22117b50dafc75c1484f1cb550e \
-    && export GOROOT_BOOTSTRAP="$(go env GOROOT)" \
-    && wget -q "$GOLANG_SRC_URL" -O golang.tar.gz \
-    && echo "$GOLANG_SRC_SHA256  golang.tar.gz" | sha256sum -c - \
-    && tar -C /usr/local -xzf golang.tar.gz \
-    && wget -q https://raw.githubusercontent.com/docker-library/golang/master/1.9/alpine3.6/no-pic.patch \
-    && cd /usr/local/go/src \
-    && patch -p2 -i /no-pic.patch \
-    && ./make.bash \
+RUN apk --no-cache add --virtual build-dependencies gcc musl-dev go git \
     && export GOPATH=/go \
-    && mkdir -p /go/src /go/bin \
-    && chmod -R 777 /go \
-
-    # Compile s3-proxy
+    && export PATH=$GOPATH/bin:$PATH \
+    && mkdir $GOPATH \
+    && chmod -R 777 $GOPATH \
     && go get -u github.com/pottava/aws-s3-proxy \
-    && mv /go/bin/aws-s3-proxy /usr/bin \
-
-    # Clean up
+    && cd /go/src/github.com/pottava/aws-s3-proxy \
+    && go build -ldflags "-s -w" \
+    && mv aws-s3-proxy /usr/bin \
     && apk del --purge -r build-dependencies \
-    && rm -rf /usr/local/go /usr/lib/go /go /golang.tar.gz /*.patch
+    && rm -rf /go
 
 EXPOSE 80