But a proper executable

apps/epp_proxy/src/epp_proxy_app.erl

@@ -15,6 +15,7 @@
 %%====================================================================
 
 start(_StartType, _StartArgs) ->
+    application:ensure_all_started(ssl),
     epp_proxy_sup:start_link().
 
 %%--------------------------------------------------------------------

apps/epp_proxy/src/epp_tcp_worker.erl

@@ -100,7 +100,6 @@ read_length(Socket) ->
 read_frame(Socket, FrameLength) ->
     case gen_tcp:recv(Socket, FrameLength) of
         {ok, Data} ->
-            io:format("Frame: ~p~n", [Data]),
             {ok, Data};
         {error, Reason} ->
             io:format("Error: ~p~n", [Reason]),

apps/epp_proxy/src/epp_tls_worker.erl

@@ -111,7 +111,6 @@ read_length(Socket) ->
 read_frame(Socket, FrameLength) ->
     case ssl:recv(Socket, FrameLength) of
         {ok, Data} ->
-            io:format("Frame: ~p~n", [Data]),
             {ok, Data};
         {error, Reason} ->
             io:format("Error: ~p~n", [Reason]),

rebar.config

@@ -4,15 +4,14 @@
 {relx, [{release, {epp_proxy, "0.1.0"},
          [epp_proxy,
           hackney,
-          sasl]},
+          sasl,
+          ssl,
+          xmerl]},
 
         {sys_config, "./config/sys.config"},
         {vm_args, "./config/vm.args"},
 
-        {dev_mode, true},
-        {include_erts, false},
-
-        {extended_start_script, true}]
+        {include_erts, true}]
 }.
 
 {profiles, [{prod, [{relx, [{dev_mode, false},