ORGANIC-443. Converted to use a smaller golang official image to speed up build.

Author: thomasyip

Dockerfile

@@ -1,10 +1,14 @@
-FROM golang:1.11.2-stretch
+FROM golang:1.11.2-alpine3.8
 
 ADD . /go/src/github.com/netlify/git-gateway
 
+RUN apk update && apk add wget && rm -rf /var/cache/apk/*
+
+RUN apk add --update alpine-sdk
+
 RUN go get github.com/Masterminds/glide
 
-RUN useradd -m netlify && cd /go/src/github.com/netlify/git-gateway && make deps build && mv git-gateway /usr/local/bin/
+RUN adduser -D -u 1000 netlify && cd /go/src/github.com/netlify/git-gateway && make deps build && mv git-gateway /usr/local/bin/
 
 USER netlify
 CMD ["git-gateway"]