add dockerfile

Dockerfile

@@ -0,0 +1,30 @@
+FROM golang:1.22-alpine AS dev
+
+COPY . /var/app
+WORKDIR /var/app
+
+ENV GO111MODULE="on" \
+    CGO_ENABLED=0 \
+    GOOS=linux
+
+EXPOSE 80
+ENTRYPOINT ["sh"]
+
+
+FROM dev as build
+
+RUN go mod download && go mod verify
+RUN go build -o ntppool-exporter main.go
+RUN chmod +x ntppool-exporter
+
+
+FROM scratch AS prod
+
+WORKDIR /app
+COPY --from=build /var/app/ntppool-exporter /bin/
+
+LABEL maintainer="Adora Laura Kalb <adora@lila.network>"
+
+EXPOSE     43609
+ENTRYPOINT ["/bin/ntppool-exporter"]
+CMD        [""]