diff --git a/src/emqx_misc.erl b/src/emqx_misc.erl index 1fd1152ce..1da1180b3 100644 --- a/src/emqx_misc.erl +++ b/src/emqx_misc.erl @@ -26,6 +26,7 @@ -export([ merge_opts/2 , maybe_apply/2 , maybe_mute_rpc_log/0 + , safe_io_device/0 , compose/1 , compose/2 , run_fold/3 @@ -478,6 +479,34 @@ maybe_mute_rpc_log(Node) -> ok end. +is_group_leader_node_connected() -> + GLNode = node(group_leader()), + case atom_to_list(GLNode) of + "remsh" ++ _ -> + {ok, Nodes} = net_kernel:nodes_info(), + lists:keymember(GLNode, 1, Nodes); + _ -> + %% for a non-remsh node + %% as long as the group leader is showing up + %% it should be connected + true + end. + +%% @doc Return 'standard_io' or 'standard_error' io device depending on the +%% current group leader node. +%% EMQX nodes do not use EPMD, there is no way for a EMQX node to connect to +%% a remsh node which is not directly connected already. +%% In this case, io:format may fail with {io,terminated} exception. +%% For io:format calls which can be evaluated from RPC calls, call this +%% function to get a safe io device. +safe_io_device() -> + case is_group_leader_node_connected() of + true -> + standard_io; + false -> + standard_error + end. + is_sensitive_key(token) -> true; is_sensitive_key("token") -> true; is_sensitive_key(<<"token">>) -> true; diff --git a/test/emqx_misc_SUITE.erl b/test/emqx_misc_SUITE.erl index e9dd3e132..5bf0d4974 100644 --- a/test/emqx_misc_SUITE.erl +++ b/test/emqx_misc_SUITE.erl @@ -179,3 +179,6 @@ t_pmap_exception(_) -> [{2, 3}, {3, 4}, error] ) ). + +t_safe_io_device(_) -> + ?assertEqual(standard_io, emqx_misc:safe_io_device()).