Allow writing custom modules in own path (#1327)

in ejabberdctl, just add this to EJABBERD_OPTS
external_beams /path/to/my/beams

then all beams file /path/to/my/beams/*.beam will be known
by ejabberd_config, and allowed to be loaded.

src/ejabberd_config.erl

@@ -978,7 +978,19 @@ default_db(Opt, Host, Module) ->
 get_modules() ->
     {ok, Mods} = application:get_key(ejabberd, modules),
     ExtMods = [Name || {Name, _Details} <- ext_mod:installed()],
-    ExtMods ++ Mods.
+    case application:get_env(ejabberd, external_beams) of
+	{ok, Path} ->
+	    case lists:member(Path, code:get_path()) of
+		true -> ok;
+		false -> code:add_patha(Path)
+	    end,
+	    Beams = filelib:wildcard(filename:join(Path, "*\.beam")),
+	    CustMods = [list_to_atom(filename:rootname(filename:basename(Beam)))
+			|| Beam <- Beams],
+	    CustMods ++ ExtMods ++ Mods;
+	_ ->
+	    ExtMods ++ Mods
+    end.
 
 get_modules_with_options(Modules) ->
     lists:foldl(