cth_log_redirect_any_domains: common_test hook to handle domain-specific log messages

common_test installs its own logger handler, which is great.
Unfortunately, this logger handler drops all messages having a domain,
except when the domain is among the domains used by Erlang itself.

In RabbitMQ, we use logger domains to categorize messages. Therefore
those messages are dropped by the common_test's logger handler.

This commit introduces another logger handler which sits on top of the
common_test one and makes sure messages with a domain are logged as
well.

3 files changed, 55 insertions, 0 deletions

diff --git a/.gitignore b/.gitignore
index 20bffb3fa9..769653969d 100644
--- a/.gitignore
+++ b/.gitignore
@@ -21,6 +21,8 @@
 !/deps/rabbitmq_cli/
 !/deps/rabbitmq_codegen/
 !/deps/rabbitmq_consistent_hash_exchange/
+!/deps/rabbitmq_ct_helpers/
+!/deps/rabbitmq_ct_client_helpers/
 !/deps/rabbitmq_event_exchange/
 !/deps/rabbitmq_federation/
 !/deps/rabbitmq_federation_management/
diff --git a/deps/rabbitmq_ct_helpers/src/cth_log_redirect_any_domains.erl b/deps/rabbitmq_ct_helpers/src/cth_log_redirect_any_domains.erl
new file mode 100644
index 0000000000..4caa1cf6fd
--- /dev/null
+++ b/deps/rabbitmq_ct_helpers/src/cth_log_redirect_any_domains.erl
@@ -0,0 +1,23 @@
+-module(cth_log_redirect_any_domains).
+
+-export([log/2]).
+
+-define(BACKEND_MODULE, cth_log_redirect).
+
+%% Reversed behavior compared to `cth_log_redirect': log events with an
+%% unknown domain are sent to the `cth_log_redirect' server, others are
+%% dropped (as they are already handled by `cth_log_redirect').
+log(#{msg:={report,_Msg},meta:=#{domain:=[otp,sasl]}},_Config) ->
+    ok;
+log(#{meta:=#{domain:=[otp]}},_Config) ->
+    ok;
+log(#{meta:=#{domain:=_}}=Log,Config) ->
+    do_log(add_log_category(Log,error_logger),Config);
+log(_Log,_Config) ->
+    ok.
+
+add_log_category(#{meta:=Meta}=Log,Category) ->
+    Log#{meta=>Meta#{?BACKEND_MODULE=>#{category=>Category}}}.
+
+do_log(Log,Config) ->
+    gen_server:call(?BACKEND_MODULE,{log,Log,Config}).
diff --git a/deps/rabbitmq_ct_helpers/src/rabbit_ct_helpers.erl b/deps/rabbitmq_ct_helpers/src/rabbit_ct_helpers.erl
index b72f4f244c..6b62f59b98 100644
--- a/deps/rabbitmq_ct_helpers/src/rabbit_ct_helpers.erl
+++ b/deps/rabbitmq_ct_helpers/src/rabbit_ct_helpers.erl
@@ -7,6 +7,7 @@
 
 -module(rabbit_ct_helpers).
 
+-include_lib("kernel/include/logger.hrl").
 -include_lib("common_test/include/ct.hrl").
 
 -deprecated({is_mixed_versions,1,"Use is_mixed_versions/0 instead"}).
@@ -26,6 +27,7 @@
     load_rabbitmqctl_app/1,
     ensure_rabbitmq_plugins_cmd/1,
     ensure_rabbitmq_queues_cmd/1,
+    redirect_logger_to_ct_logs/1,
     init_skip_as_error_flag/1,
     start_long_running_testsuite_monitor/1,
     stop_long_running_testsuite_monitor/1,
@@ -155,6 +157,34 @@ run_steps(Config, [Step | Rest]) ->
 run_steps(Config, []) ->
     Config.
 
+redirect_logger_to_ct_logs(Config) ->
+    ct:pal(
+      ?LOW_IMPORTANCE,
+      "Configuring logger to send logs to common_test logs"),
+    logger:set_handler_config(cth_log_redirect, level, debug),
+
+    %% Let's use the same format as RabbitMQ itself.
+    logger:set_handler_config(
+      cth_log_redirect, formatter,
+      rabbit_prelaunch_early_logging:default_file_formatter(#{})),
+
+    %% We use an addition logger handler for messages tagged with a non-OTP
+    %% domain because by default, `cth_log_redirect' drop them.
+    {ok, LogCfg0} = logger:get_handler_config(cth_log_redirect),
+    LogCfg = maps:remove(id, maps:remove(module, LogCfg0)),
+    ok = logger:add_handler(
+           cth_log_redirect_any_domains, cth_log_redirect_any_domains,
+           LogCfg),
+
+    logger:remove_handler(default),
+
+    ct:pal(
+      ?LOW_IMPORTANCE,
+      "Logger configured to send logs to common_test logs; you should see "
+      "a message below saying so"),
+    ?LOG_INFO("Logger message logged to common_test logs"),
+    Config.
+
 init_skip_as_error_flag(Config) ->
     SkipAsError = case os:getenv("RABBITMQ_CT_SKIP_AS_ERROR") of
                       false -> false;