Add port to serve to ENV variables

Dockerfile

@@ -10,4 +10,5 @@ WORKDIR /app
 COPY --from=build-env /src/proxy /app/
 ENV SOCKS_USER=user
 ENV SOCKS_PASSWORD=password
+ENV PROXY_PORT=1080
 CMD ["./proxy"]

main.go

@@ -71,7 +71,11 @@ func main() {
 	if err != nil {
 		panic(err)
 	}
-	if err := server.ListenAndServe("tcp", "0.0.0.0:1080"); err != nil {
+	port := os.Getenv("PROXY_PORT")
+	if port == "" {
+		port = "1080"
+	}
+	if err := server.ListenAndServe("tcp", "0.0.0.0:" + port); err != nil {
 		panic(err)
 	}
 }