Change Dockerfile to multi stage build

Dockerfile

@@ -1,26 +1,14 @@
-FROM frolvlad/alpine-glibc:alpine-3.5
-
-ARG PROMETHEUS_SQL_VERSION=1.2.0
-ARG PKG_FILE=prometheus-sql-linux-amd64.tar.gz
-ARG PKG_URL=https://github.com/chop-dbhi/prometheus-sql/releases/download/$PROMETHEUS_SQL_VERSION/$PKG_FILE
-
-RUN apk update
-RUN apk add curl
-
-# Workaround to publish Github release before curl fetches it.
-RUN sleep 60
-
-RUN mkdir -p /opt/prometheus-sql/bin \
-    && curl --retry 5 --retry-delay 15 --retry-max-time 120 -SL $PKG_URL \
-    | tar -xzC /opt/prometheus-sql/bin \
-    && ln -s /opt/prometheus-sql/bin/linux-amd64/prometheus-sql /usr/local/bin/
-
-RUN apk del curl
-RUN rm /var/cache/apk/*
+# Requires Docker v17.06 or later
+FROM golang:1.8.3 as builder
+RUN mkdir -p /go/src/app
+WORKDIR /go/src/app
+COPY . /go/src/app
+RUN go-wrapper download
+RUN go-wrapper install
 
+FROM frolvlad/alpine-glibc:alpine-3.5
+COPY --from=builder /go/bin/app /usr/local/bin/prometheus-sql
 EXPOSE 8080
-
 ENTRYPOINT ["/usr/local/bin/prometheus-sql", "-host", "0.0.0.0"]
-
 # Default command assumes the SQL agent is linked.
 CMD ["-service", "http://sqlagent:5000"]