make httppoison use configurable http proxy

config/config.exs

@@ -32,7 +32,7 @@
 
 config :pleroma, :websub, Pleroma.Web.Websub
 config :pleroma, :ostatus, Pleroma.Web.OStatus
-config :pleroma, :httpoison, HTTPoison
+config :pleroma, :httpoison, Pleroma.HTTP
 
 version = with {version, 0} <- System.cmd("git", ["rev-parse", "HEAD"]) do
             "Pleroma #{String.trim(version)}"
@@ -40,6 +40,9 @@
             _ -> "Pleroma dev"
           end
 
+config :pleroma, :http,
+  proxy_url: ""
+
 config :pleroma, :instance,
   version: version,
   name: "Pleroma",

lib/pleroma/http/http.ex

@@ -0,0 +1,14 @@
+
+defmodule Pleroma.HTTP do
+  use HTTPoison.Base
+
+  def process_request_options(options) do
+    config = Application.get_env(:pleroma, :http, [])
+    proxy = Keyword.get(config, :proxy_url, "")
+    case proxy do
+      "" -> options
+      _ -> options ++ [proxy: proxy]
+    end
+  end
+
+end