Merge pull request fluent#4188 from daipom/fix-logger-setup-failure

Fix failure to launch Fluentd on Windows with log rotation but not specifying the log path in the command line

lib/fluent/supervisor.rb

@@ -697,7 +697,7 @@ def setup_global_logger(supervisor: false)
       actual_log_path = @log_path
 
       # We need to prepare a unique path for each worker since Windows locks files.
-      if Fluent.windows? && rotate
+      if Fluent.windows? && rotate && @log_path && @log_path != "-"
         actual_log_path = Fluent::Log.per_process_path(@log_path, process_type, worker_id)
       end
 

test/test_supervisor.rb

@@ -621,6 +621,19 @@ def test_logger_with_rotate_age_and_rotate_size(rotate_age)
       assert_equal 10, $log.out.instance_variable_get(:@shift_size)
     end
 
+    def test_can_start_with_rotate_but_no_log_path
+      config_path = "#{@tmp_dir}/empty.conf"
+      write_config config_path, ""
+
+      sv = Fluent::Supervisor.new(
+        config_path: config_path,
+        log_rotate_age: 5,
+      )
+      sv.__send__(:setup_global_logger)
+
+      assert_true $log.stdout?
+    end
+
     sub_test_case "system log rotation" do
       def parse_text(text)
         basepath = File.expand_path(File.dirname(__FILE__) + '/../../')