add: add Dockerfile

Dockerfile

@@ -0,0 +1,15 @@
+FROM alpine as build
+
+ADD ./build/app /app
+
+RUN sed -i 's/dl-cdn.alpinelinux.org/mirrors.ustc.edu.cn/g' /etc/apk/repositories \
+    && apk --no-cache add ca-certificates
+
+FROM scratch
+# copy the ca-certificate.crt from the build stage
+COPY --from=build /etc/ssl/certs/ca-certificates.crt /etc/ssl/certs/
+COPY --from=build /app /app
+
+EXPOSE 13721
+
+ENTRYPOINT ["/app"]