Added upx to shrink docker image to ~2MB

Dockerfile

@@ -4,17 +4,18 @@ WORKDIR /go/src/github.com/eko/pihole-exporter
 COPY . .
 
 RUN apk update && \
-    apk --no-cache add git alpine-sdk
+    apk --no-cache add git alpine-sdk upx
 
 RUN GO111MODULE=on go mod vendor
-RUN CGO_ENABLED=0 GOOS=linux GOARCH=amd64 go build -ldflags '-w' -o binary ./
+RUN CGO_ENABLED=0 GOOS=linux GOARCH=amd64 go build -ldflags '-s -w' -o go-binary ./
+
+RUN upx -f --brute -o binary go-binary
 
 FROM scratch
 
 LABEL name="pihole-exporter"
 
 WORKDIR /root/
-
 COPY --from=builder /go/src/github.com/eko/pihole-exporter/binary pihole-exporter
 
 CMD ["./pihole-exporter"]