add Dockerfile

Dockerfile

@@ -0,0 +1,20 @@
+FROM rust:1-alpine as build
+
+# sys deps
+RUN apk add --no-cache musl-dev libc-dev
+
+# cache index
+RUN cargo search doh-proxy
+
+RUN cargo install doh-proxy --no-default-features
+
+# -----------
+
+FROM busybox:1-musl
+
+COPY --from=build /usr/local/cargo/bin/doh-proxy /usr/local/bin/doh-proxy 
+
+EXPOSE 3000/tcp
+
+CMD ["doh-proxy"]
+