Add exporter

Dockerfile

@@ -0,0 +1,12 @@
+# Build stage
+FROM golang:1.17-alpine AS build
+WORKDIR /app
+COPY . .
+RUN go build -o /livebox-exporter
+# Final image
+FROM alpine:3.14
+WORKDIR /
+COPY --from=build /livebox-exporter /usr/local/bin/livebox-exporter
+EXPOSE 8080
+USER 10001:10001
+ENTRYPOINT ["livebox-exporter"]