add Dockerfile

Signed-off-by: Andreas Schmid <service@aaschmid.de>

Dockerfile

@@ -0,0 +1,22 @@
+FROM golang:1.14.5 AS build-env
+
+LABEL maintainer="Max Schmitt <max@schmitt.mx>"
+LABEL maintainer="Andreas Schmid <service@aaschid.de>"
+LABEL description="FRITZ!Box Prometheus exporter"
+
+RUN go get -v github.com/aaschmid/fritzbox_exporter && \
+    cd /go/src/github.com/aaschmid/fritzbox_exporter && \
+    CGO_ENABLED=0 go build -v -o /exporter
+
+
+FROM alpine
+
+RUN apk update && apk add ca-certificates
+
+COPY --from=build-env /go/src/github.com/aaschmid/fritzbox_exporter/metrics.json /metrics.json
+COPY --from=build-env /exporter /
+
+EXPOSE 9133
+
+ENTRYPOINT ["/exporter"]
+CMD ["-listen-address", ":9133", "-metrics-file", "/metrics.json"]