warn recommended exclusion path for antivirus

It might be better to notify about recommended exclusion path for
antivirus.

Typically pos file or storage local file might be scanned by
antivirus thus there might be possibility to be locked by them.

Signed-off-by: Kentaro Hayashi <hayashi@clear-code.com>

Author: kenhys

lib/fluent/supervisor.rb

@@ -814,6 +814,20 @@ def configure(supervisor: false)
         @conf += additional_conf
       end
 
+      if Fluent.windows?
+        @conf.elements.each do |element|
+          next unless element.name == 'source'
+          if element['@type'] == 'tail' && element['pos_file']
+            $log.warn("Recommend adding #{File.dirname(element['pos_file'])} to the exclusion path of your antivirus software on Windows")
+          else
+            storage = element.elements.find { |v| v.name == 'storage' and v['@type'] == 'local' and v['persistent'] == 'true' }
+            if storage and storage['path']
+              $log.warn("Recommend adding #{File.dirname(storage['path'])} to the exclusion path of your antivirus software on Windows")
+            end
+          end
+        end
+      end
+
       @libs.each do |lib|
         require lib
       end

test/command/test_fluentd.rb

@@ -1679,4 +1679,63 @@ def create_config_include_dir_configuration(config_path, config_dir, yaml_format
     end
   end
 
+  sub_test_case "test problematic antivirus exclusion path on Windows" do
+    test "warn pos_file path" do
+      omit "skip antivirus exclusion path about in_tail pos_file (Windows)" unless Fluent.windows?
+      conf_path = create_conf_file("warn_pos_file_dir.conf", <<~EOF)
+        <system>
+          config_include_dir ""
+        </system>
+        <source>
+          @type tail
+          tag t1
+          path #{@tmp_dir}/test.log
+          pos_file #{@tmp_dir}/test.pos
+        </source>
+      EOF
+      expected_warning_message = "[warn]: Recommend adding #{@tmp_dir} to the exclusion path of your antivirus software on Windows"
+      assert_log_matches(create_cmdline(conf_path, '--dry-run'),
+                         expected_warning_message)
+    end
+
+    test "warn storage path" do
+      omit "skip antivirus exclusion path about storage local (Windows)" unless Fluent.windows?
+      conf_path = create_conf_file("warn_storage_local_path.conf", <<~EOF)
+        <system>
+          config_include_dir ""
+        </system>
+        <source>
+          @type sample
+          tag t1
+          <storage>
+            @type local
+            persistent true
+            path #{@tmp_dir}/test.pos
+          </storage>
+        </source>
+      EOF
+      expected_warning_message = "[warn]: Recommend adding #{@tmp_dir} to the exclusion path of your antivirus software on Windows"
+      assert_log_matches(create_cmdline(conf_path, '--dry-run'),
+                         expected_warning_message)
+    end
+
+    test "no warn storage local on memory" do
+      omit "skip antivirus exclusion path about memory storage local (Windows)" unless Fluent.windows?
+      conf_path = create_conf_file("no_warn_storage_local.conf", <<~EOF)
+        <system>
+          config_include_dir ""
+        </system>
+        <source>
+          @type sample
+          tag t1
+          <storage>
+            @type local
+          </storage>
+        </source>
+      EOF
+      expected_warning_message = "[warn]: Recommend adding #{@tmp_dir} to the exclusion path of your antivirus software on Windows"
+      assert_log_matches(create_cmdline(conf_path, '--dry-run'),
+                         "Using on-memory store.", patterns_not_match: [expected_warning_message])
+    end
+  end
 end