Update default category loglevel to `inherit`

Change default level for categories to make them log
`debug` messages if there is a handler to output them.

2 files changed, 87 insertions, 83 deletions

diff --git a/src/rabbit_lager.erl b/src/rabbit_lager.erl
index db45b61072..14aa3d31f6 100644
--- a/src/rabbit_lager.erl
+++ b/src/rabbit_lager.erl
@@ -392,19 +392,23 @@ set_env_upgrade_log_file(FileName) ->
 generate_lager_sinks(SinkNames, SinkConfigs) ->
     lists:map(fun(SinkName) ->
         SinkConfig = proplists:get_value(SinkName, SinkConfigs, []),
-        Level = proplists:get_value(level, SinkConfig, default_config_value(level)),
         SinkHandlers = case proplists:get_value(file, SinkConfig, false) of
             %% If no file defined - forward everything to the default backend
             false ->
+                ForwarderLevel = proplists:get_value(level, SinkConfig, inherit),
                 [{lager_forwarder_backend,
-                    [lager_util:make_internal_sink_name(lager), Level]}];
+                    [lager_util:make_internal_sink_name(lager), ForwarderLevel]}];
             %% If a file defined - add a file backend to handlers and remove all default file backends.
             File ->
+                %% Use `debug` as a default handler to not override a handler level
+                Level = proplists:get_value(level, SinkConfig, debug),
                 DefaultGeneratedHandlers = application:get_env(lager, rabbit_handlers, []),
                 SinkFileHandlers = case proplists:get_value(lager_file_backend, DefaultGeneratedHandlers, undefined) of
                     undefined ->
                         %% Create a new file handler.
-                        generate_lager_handlers([{file, [{file, File}, {level, Level}]}]);
+                        %% `info` is a default level here.
+                        FileLevel = proplists:get_value(level, SinkConfig, default_config_value(level)),
+                        generate_lager_handlers([{file, [{file, File}, {level, FileLevel}]}]);
                     FileHandler ->
                         %% Replace a filename in the handler
                         FileHandlerChanges = case handler_level_more_verbose(FileHandler, Level) of
diff --git a/test/unit_log_config_SUITE.erl b/test/unit_log_config_SUITE.erl
index c5a9417723..7f4c5e685c 100644
--- a/test/unit_log_config_SUITE.erl
+++ b/test/unit_log_config_SUITE.erl
@@ -92,14 +92,14 @@ sink_file_rewrites_file_backends(_) ->
 
 sink_rewrite_sinks() ->
     [{error_logger_lager_event,
-        [{handlers,[{lager_forwarder_backend,[lager_event,info]}]},
-         {rabbit_handlers,[{lager_forwarder_backend,[lager_event,info]}]}]},
+        [{handlers,[{lager_forwarder_backend,[lager_event,inherit]}]},
+         {rabbit_handlers,[{lager_forwarder_backend,[lager_event,inherit]}]}]},
      {rabbit_log_channel_lager_event,
-        [{handlers,[{lager_forwarder_backend,[lager_event,info]}]},
-         {rabbit_handlers,[{lager_forwarder_backend,[lager_event,info]}]}]},
+        [{handlers,[{lager_forwarder_backend,[lager_event,inherit]}]},
+         {rabbit_handlers,[{lager_forwarder_backend,[lager_event,inherit]}]}]},
      {rabbit_log_connection_lager_event,
-        [{handlers,[{lager_forwarder_backend,[lager_event,info]}]},
-         {rabbit_handlers,[{lager_forwarder_backend,[lager_event,info]}]}]},
+        [{handlers,[{lager_forwarder_backend,[lager_event,inherit]}]},
+         {rabbit_handlers,[{lager_forwarder_backend,[lager_event,inherit]}]}]},
      {rabbit_log_federation_lager_event,
         [{handlers,[
             {lager_file_backend,
@@ -120,17 +120,17 @@ sink_rewrite_sinks() ->
             {lager_console_backend, [{level, warning}]}
         ]}]},
      {rabbit_log_lager_event,
-        [{handlers,[{lager_forwarder_backend,[lager_event,info]}]},
-         {rabbit_handlers,[{lager_forwarder_backend,[lager_event,info]}]}]},
+        [{handlers,[{lager_forwarder_backend,[lager_event,inherit]}]},
+         {rabbit_handlers,[{lager_forwarder_backend,[lager_event,inherit]}]}]},
      {rabbit_log_mirroring_lager_event,
-        [{handlers,[{lager_forwarder_backend,[lager_event,info]}]},
-         {rabbit_handlers,[{lager_forwarder_backend,[lager_event,info]}]}]},
+        [{handlers,[{lager_forwarder_backend,[lager_event,inherit]}]},
+         {rabbit_handlers,[{lager_forwarder_backend,[lager_event,inherit]}]}]},
      {rabbit_log_queue_lager_event,
-        [{handlers,[{lager_forwarder_backend,[lager_event,info]}]},
-         {rabbit_handlers,[{lager_forwarder_backend,[lager_event,info]}]}]},
+        [{handlers,[{lager_forwarder_backend,[lager_event,inherit]}]},
+         {rabbit_handlers,[{lager_forwarder_backend,[lager_event,inherit]}]}]},
      {rabbit_log_upgrade_lager_event,
-        [{handlers,[{lager_forwarder_backend,[lager_event,info]}]},
-         {rabbit_handlers,[{lager_forwarder_backend,[lager_event,info]}]}]}
+        [{handlers,[{lager_forwarder_backend,[lager_event,inherit]}]},
+         {rabbit_handlers,[{lager_forwarder_backend,[lager_event,inherit]}]}]}
      ].
 
 
@@ -161,8 +161,8 @@ sink_handlers_merged_with_lager_extra_sinks_handlers(_) ->
 
     ExpectedSinks = sort_sinks([
         {error_logger_lager_event,
-            [{handlers,[{lager_forwarder_backend,[lager_event,info]}]},
-             {rabbit_handlers,[{lager_forwarder_backend,[lager_event,info]}]}]},
+            [{handlers,[{lager_forwarder_backend,[lager_event,inherit]}]},
+             {rabbit_handlers,[{lager_forwarder_backend,[lager_event,inherit]}]}]},
          {rabbit_log_channel_lager_event,
             [{handlers,[
                 {lager_console_backend, [{level, error},
@@ -192,20 +192,20 @@ sink_handlers_merged_with_lager_extra_sinks_handlers(_) ->
                         {lager_file_backend, [{file, "connection_lager.log"}, {level, info}]}]},
              {rabbit_handlers,[{lager_forwarder_backend,[lager_event,debug]}]}]},
          {rabbit_log_federation_lager_event,
-            [{handlers,[{lager_forwarder_backend,[lager_event,info]}]},
-             {rabbit_handlers,[{lager_forwarder_backend,[lager_event,info]}]}]},
+            [{handlers,[{lager_forwarder_backend,[lager_event,inherit]}]},
+             {rabbit_handlers,[{lager_forwarder_backend,[lager_event,inherit]}]}]},
          {rabbit_log_lager_event,
-            [{handlers,[{lager_forwarder_backend,[lager_event,info]}]},
-             {rabbit_handlers,[{lager_forwarder_backend,[lager_event,info]}]}]},
+            [{handlers,[{lager_forwarder_backend,[lager_event,inherit]}]},
+             {rabbit_handlers,[{lager_forwarder_backend,[lager_event,inherit]}]}]},
          {rabbit_log_mirroring_lager_event,
-            [{handlers,[{lager_forwarder_backend,[lager_event,info]}]},
-             {rabbit_handlers,[{lager_forwarder_backend,[lager_event,info]}]}]},
+            [{handlers,[{lager_forwarder_backend,[lager_event,inherit]}]},
+             {rabbit_handlers,[{lager_forwarder_backend,[lager_event,inherit]}]}]},
          {rabbit_log_queue_lager_event,
-            [{handlers,[{lager_forwarder_backend,[lager_event,info]}]},
-             {rabbit_handlers,[{lager_forwarder_backend,[lager_event,info]}]}]},
+            [{handlers,[{lager_forwarder_backend,[lager_event,inherit]}]},
+             {rabbit_handlers,[{lager_forwarder_backend,[lager_event,inherit]}]}]},
          {rabbit_log_upgrade_lager_event,
-            [{handlers,[{lager_forwarder_backend,[lager_event,info]}]},
-             {rabbit_handlers,[{lager_forwarder_backend,[lager_event,info]}]}]}]),
+            [{handlers,[{lager_forwarder_backend,[lager_event,inherit]}]},
+             {rabbit_handlers,[{lager_forwarder_backend,[lager_event,inherit]}]}]}]),
 
     ?assertEqual(ExpectedSinks, sort_sinks(application:get_env(lager, extra_sinks, undefined))).
 
@@ -254,8 +254,8 @@ config_sinks_level(_) ->
 
 level_sinks() ->
     [{error_logger_lager_event,
-        [{handlers,[{lager_forwarder_backend,[lager_event,info]}]},
-         {rabbit_handlers,[{lager_forwarder_backend,[lager_event,info]}]}]},
+        [{handlers,[{lager_forwarder_backend,[lager_event,inherit]}]},
+         {rabbit_handlers,[{lager_forwarder_backend,[lager_event,inherit]}]}]},
      {rabbit_log_channel_lager_event,
         [{handlers,[{lager_forwarder_backend,[lager_event,debug]}]},
          {rabbit_handlers,[{lager_forwarder_backend,[lager_event,debug]}]}]},
@@ -263,20 +263,20 @@ level_sinks() ->
         [{handlers,[{lager_forwarder_backend,[lager_event,warning]}]},
          {rabbit_handlers,[{lager_forwarder_backend,[lager_event,warning]}]}]},
      {rabbit_log_federation_lager_event,
-        [{handlers,[{lager_forwarder_backend,[lager_event,info]}]},
-         {rabbit_handlers,[{lager_forwarder_backend,[lager_event,info]}]}]},
+        [{handlers,[{lager_forwarder_backend,[lager_event,inherit]}]},
+         {rabbit_handlers,[{lager_forwarder_backend,[lager_event,inherit]}]}]},
      {rabbit_log_lager_event,
-        [{handlers,[{lager_forwarder_backend,[lager_event,info]}]},
-         {rabbit_handlers,[{lager_forwarder_backend,[lager_event,info]}]}]},
+        [{handlers,[{lager_forwarder_backend,[lager_event,inherit]}]},
+         {rabbit_handlers,[{lager_forwarder_backend,[lager_event,inherit]}]}]},
      {rabbit_log_mirroring_lager_event,
         [{handlers,[{lager_forwarder_backend,[lager_event,error]}]},
          {rabbit_handlers,[{lager_forwarder_backend,[lager_event,error]}]}]},
      {rabbit_log_queue_lager_event,
-        [{handlers,[{lager_forwarder_backend,[lager_event,info]}]},
-         {rabbit_handlers,[{lager_forwarder_backend,[lager_event,info]}]}]},
+        [{handlers,[{lager_forwarder_backend,[lager_event,inherit]}]},
+         {rabbit_handlers,[{lager_forwarder_backend,[lager_event,inherit]}]}]},
      {rabbit_log_upgrade_lager_event,
-        [{handlers,[{lager_forwarder_backend,[lager_event,info]}]},
-         {rabbit_handlers,[{lager_forwarder_backend,[lager_event,info]}]}]}
+        [{handlers,[{lager_forwarder_backend,[lager_event,inherit]}]},
+         {rabbit_handlers,[{lager_forwarder_backend,[lager_event,inherit]}]}]}
      ].
 
 config_sink_file(_) ->
@@ -318,11 +318,11 @@ config_sink_file_override_config_handler_file(_) ->
 
 file_sinks() ->
     [{error_logger_lager_event,
-        [{handlers,[{lager_forwarder_backend,[lager_event,info]}]},
-         {rabbit_handlers,[{lager_forwarder_backend,[lager_event,info]}]}]},
+        [{handlers,[{lager_forwarder_backend,[lager_event,inherit]}]},
+         {rabbit_handlers,[{lager_forwarder_backend,[lager_event,inherit]}]}]},
      {rabbit_log_channel_lager_event,
-        [{handlers,[{lager_forwarder_backend,[lager_event,info]}]},
-         {rabbit_handlers,[{lager_forwarder_backend,[lager_event,info]}]}]},
+        [{handlers,[{lager_forwarder_backend,[lager_event,inherit]}]},
+         {rabbit_handlers,[{lager_forwarder_backend,[lager_event,inherit]}]}]},
      {rabbit_log_connection_lager_event,
         [{handlers,[
             {lager_console_backend, [{level, warning},
@@ -344,20 +344,20 @@ file_sinks() ->
                  {size, 0}]}]}
          ]},
      {rabbit_log_federation_lager_event,
-        [{handlers,[{lager_forwarder_backend,[lager_event,info]}]},
-         {rabbit_handlers,[{lager_forwarder_backend,[lager_event,info]}]}]},
+        [{handlers,[{lager_forwarder_backend,[lager_event,inherit]}]},
+         {rabbit_handlers,[{lager_forwarder_backend,[lager_event,inherit]}]}]},
      {rabbit_log_lager_event,
-        [{handlers,[{lager_forwarder_backend,[lager_event,info]}]},
-         {rabbit_handlers,[{lager_forwarder_backend,[lager_event,info]}]}]},
+        [{handlers,[{lager_forwarder_backend,[lager_event,inherit]}]},
+         {rabbit_handlers,[{lager_forwarder_backend,[lager_event,inherit]}]}]},
      {rabbit_log_mirroring_lager_event,
-        [{handlers,[{lager_forwarder_backend,[lager_event,info]}]},
-         {rabbit_handlers,[{lager_forwarder_backend,[lager_event,info]}]}]},
+        [{handlers,[{lager_forwarder_backend,[lager_event,inherit]}]},
+         {rabbit_handlers,[{lager_forwarder_backend,[lager_event,inherit]}]}]},
      {rabbit_log_queue_lager_event,
-        [{handlers,[{lager_forwarder_backend,[lager_event,info]}]},
-         {rabbit_handlers,[{lager_forwarder_backend,[lager_event,info]}]}]},
+        [{handlers,[{lager_forwarder_backend,[lager_event,inherit]}]},
+         {rabbit_handlers,[{lager_forwarder_backend,[lager_event,inherit]}]}]},
      {rabbit_log_upgrade_lager_event,
-        [{handlers,[{lager_forwarder_backend,[lager_event,info]}]},
-         {rabbit_handlers,[{lager_forwarder_backend,[lager_event,info]}]}]}
+        [{handlers,[{lager_forwarder_backend,[lager_event,inherit]}]},
+         {rabbit_handlers,[{lager_forwarder_backend,[lager_event,inherit]}]}]}
      ].
 
 
@@ -545,26 +545,26 @@ default_expected_handlers(File, Level, RotSize, RotDate, Extra) ->
 
 default_expected_sinks(UpgradeFile) ->
     [{error_logger_lager_event,
-        [{handlers,[{lager_forwarder_backend,[lager_event,info]}]},
-         {rabbit_handlers,[{lager_forwarder_backend,[lager_event,info]}]}]},
+        [{handlers,[{lager_forwarder_backend,[lager_event,inherit]}]},
+         {rabbit_handlers,[{lager_forwarder_backend,[lager_event,inherit]}]}]},
      {rabbit_log_channel_lager_event,
-        [{handlers,[{lager_forwarder_backend,[lager_event,info]}]},
-         {rabbit_handlers,[{lager_forwarder_backend,[lager_event,info]}]}]},
+        [{handlers,[{lager_forwarder_backend,[lager_event,inherit]}]},
+         {rabbit_handlers,[{lager_forwarder_backend,[lager_event,inherit]}]}]},
      {rabbit_log_connection_lager_event,
-        [{handlers,[{lager_forwarder_backend,[lager_event,info]}]},
-         {rabbit_handlers,[{lager_forwarder_backend,[lager_event,info]}]}]},
+        [{handlers,[{lager_forwarder_backend,[lager_event,inherit]}]},
+         {rabbit_handlers,[{lager_forwarder_backend,[lager_event,inherit]}]}]},
      {rabbit_log_federation_lager_event,
-        [{handlers,[{lager_forwarder_backend,[lager_event,info]}]},
-         {rabbit_handlers,[{lager_forwarder_backend,[lager_event,info]}]}]},
+        [{handlers,[{lager_forwarder_backend,[lager_event,inherit]}]},
+         {rabbit_handlers,[{lager_forwarder_backend,[lager_event,inherit]}]}]},
      {rabbit_log_lager_event,
-        [{handlers,[{lager_forwarder_backend,[lager_event,info]}]},
-         {rabbit_handlers,[{lager_forwarder_backend,[lager_event,info]}]}]},
+        [{handlers,[{lager_forwarder_backend,[lager_event,inherit]}]},
+         {rabbit_handlers,[{lager_forwarder_backend,[lager_event,inherit]}]}]},
      {rabbit_log_mirroring_lager_event,
-        [{handlers,[{lager_forwarder_backend,[lager_event,info]}]},
-         {rabbit_handlers,[{lager_forwarder_backend,[lager_event,info]}]}]},
+        [{handlers,[{lager_forwarder_backend,[lager_event,inherit]}]},
+         {rabbit_handlers,[{lager_forwarder_backend,[lager_event,inherit]}]}]},
      {rabbit_log_queue_lager_event,
-        [{handlers,[{lager_forwarder_backend,[lager_event,info]}]},
-         {rabbit_handlers,[{lager_forwarder_backend,[lager_event,info]}]}]},
+        [{handlers,[{lager_forwarder_backend,[lager_event,inherit]}]},
+         {rabbit_handlers,[{lager_forwarder_backend,[lager_event,inherit]}]}]},
      {rabbit_log_upgrade_lager_event,
         [{handlers,
             [{lager_file_backend,
@@ -605,29 +605,29 @@ tty_expected_handlers() ->
 
 tty_expected_sinks() ->
     [{error_logger_lager_event,
-        [{handlers,[{lager_forwarder_backend,[lager_event,info]}]},
-         {rabbit_handlers,[{lager_forwarder_backend,[lager_event,info]}]}]},
+        [{handlers,[{lager_forwarder_backend,[lager_event,inherit]}]},
+         {rabbit_handlers,[{lager_forwarder_backend,[lager_event,inherit]}]}]},
      {rabbit_log_channel_lager_event,
-        [{handlers,[{lager_forwarder_backend,[lager_event,info]}]},
-         {rabbit_handlers,[{lager_forwarder_backend,[lager_event,info]}]}]},
+        [{handlers,[{lager_forwarder_backend,[lager_event,inherit]}]},
+         {rabbit_handlers,[{lager_forwarder_backend,[lager_event,inherit]}]}]},
      {rabbit_log_connection_lager_event,
-        [{handlers,[{lager_forwarder_backend,[lager_event,info]}]},
-         {rabbit_handlers,[{lager_forwarder_backend,[lager_event,info]}]}]},
+        [{handlers,[{lager_forwarder_backend,[lager_event,inherit]}]},
+         {rabbit_handlers,[{lager_forwarder_backend,[lager_event,inherit]}]}]},
      {rabbit_log_federation_lager_event,
-        [{handlers,[{lager_forwarder_backend,[lager_event,info]}]},
-         {rabbit_handlers,[{lager_forwarder_backend,[lager_event,info]}]}]},
+        [{handlers,[{lager_forwarder_backend,[lager_event,inherit]}]},
+         {rabbit_handlers,[{lager_forwarder_backend,[lager_event,inherit]}]}]},
      {rabbit_log_lager_event,
-        [{handlers, [{lager_forwarder_backend,[lager_event,info]}]},
-         {rabbit_handlers, [{lager_forwarder_backend,[lager_event,info]}]}]},
+        [{handlers, [{lager_forwarder_backend,[lager_event,inherit]}]},
+         {rabbit_handlers, [{lager_forwarder_backend,[lager_event,inherit]}]}]},
      {rabbit_log_mirroring_lager_event,
-        [{handlers,[{lager_forwarder_backend,[lager_event,info]}]},
-         {rabbit_handlers,[{lager_forwarder_backend,[lager_event,info]}]}]},
+        [{handlers,[{lager_forwarder_backend,[lager_event,inherit]}]},
+         {rabbit_handlers,[{lager_forwarder_backend,[lager_event,inherit]}]}]},
      {rabbit_log_queue_lager_event,
-        [{handlers,[{lager_forwarder_backend,[lager_event,info]}]},
-         {rabbit_handlers,[{lager_forwarder_backend,[lager_event,info]}]}]},
+        [{handlers,[{lager_forwarder_backend,[lager_event,inherit]}]},
+         {rabbit_handlers,[{lager_forwarder_backend,[lager_event,inherit]}]}]},
      {rabbit_log_upgrade_lager_event,
-        [{handlers,[{lager_forwarder_backend,[lager_event,info]}]},
-         {rabbit_handlers,[{lager_forwarder_backend,[lager_event,info]}]}]}].
+        [{handlers,[{lager_forwarder_backend,[lager_event,inherit]}]},
+         {rabbit_handlers,[{lager_forwarder_backend,[lager_event,inherit]}]}]}].
 
 sort_sinks(Sinks) ->
     lists:ukeysort(1,