How to send request from HTTPoison with proxy in docker

if I understood what you said, I should create a firewall rule to filter this container internet , shouldn’t I ? if your answer is okay, would you mind telling me how I can do this ? because I tried to create iptables rule to filter and limit to just Google Api, but I couldn’t !!

my docker network was linked by internal domain like: http://elixir_api or http://elixir_html, how can I filter its internet for example http://elixir_html, that it just send and receive from google not another domain

Thanks