So you are getting a 301 redirect, precisely you are being redirected from http:// to https://.
You can use just http:// in the original URL, or configure HTTPoison to follow redirects like this: httpoison/test/httpoison_test.exs at 3481d567adcb06d129dfec3c69aa87d1719f7a8b · edgurgel/httpoison · GitHub
