diff --git a/app/controllers/fluentd/settings/in_tail_controller.rb b/app/controllers/fluentd/settings/in_tail_controller.rb
index 90489cd..e821500 100644
--- a/app/controllers/fluentd/settings/in_tail_controller.rb
+++ b/app/controllers/fluentd/settings/in_tail_controller.rb
@@ -38,10 +38,7 @@ class Fluentd::Settings::InTailController < ApplicationController
       return render "after_format"
     end
 
-    File.open(@fluentd.agent.config_file, "a") do |f| # TODO: should update by agent class
-      f.write "\n"
-      f.write @setting.to_conf
-    end
+    @fluentd.agent.config_append @setting.to_conf
     @fluentd.agent.restart if @fluentd.agent.running?
     redirect_to fluentd_setting_path(@fluentd)
   end
diff --git a/app/controllers/fluentd/settings_controller.rb b/app/controllers/fluentd/settings_controller.rb
index 6ac3a1b..946f5f4 100644
--- a/app/controllers/fluentd/settings_controller.rb
+++ b/app/controllers/fluentd/settings_controller.rb
@@ -3,17 +3,15 @@ class Fluentd::SettingsController < ApplicationController
   before_action :find_fluentd
 
   def show
-    @config = File.read(@fluentd.agent.config_file) # TODO
+    @config = @fluentd.agent.config
   end
 
   def edit
-    @config = File.read(@fluentd.agent.config_file) # TODO
+    @config = @fluentd.agent.config
   end
 
   def  update
-    File.open(@fluentd.agent.config_file, "w") do |f| # TODO: should update by agent class
-      f.write params[:config]
-    end
+    @fluentd.agent.config_write params[:config]
     @fluentd.agent.restart if @fluentd.agent.running?
     redirect_to fluentd_setting_path(@fluentd)
   end
@@ -54,10 +52,7 @@ class Fluentd::SettingsController < ApplicationController
       return render "in_tail_after_format"
     end
 
-    File.open(@fluentd.agent.config_file, "a") do |f| # TODO: should update by agent class
-      f.write "\n"
-      f.write @setting.to_conf
-    end
+    @fluentd.agent.config_append @setting.to_conf
     @fluentd.agent.restart if @fluentd.agent.running?
     redirect_to fluentd_setting_path(@fluentd)
   end
diff --git a/app/models/fluentd/agent/common.rb b/app/models/fluentd/agent/common.rb
index dcc1f24..49f88f8 100644
--- a/app/models/fluentd/agent/common.rb
+++ b/app/models/fluentd/agent/common.rb
@@ -45,6 +45,23 @@ class Fluentd
         File.read(log_file) # TODO: large log file
       end
 
+      def config
+        File.read(config_file)
+      end
+
+      def config_write(content)
+        File.open(config_file, "w") do |f|
+          f.write content
+        end
+      end
+
+      def config_append(content)
+        File.open(config_file, "a") do |f|
+          f.write "\n"
+          f.write content
+        end
+      end
+
       def errors_since(since = 1.day.ago)
         errors = []
         logged_errors do |error|
diff --git a/app/views/plugins/installed.html.haml b/app/views/plugins/installed.html.haml
index 4e79c63..78475f5 100644
--- a/app/views/plugins/installed.html.haml
+++ b/app/views/plugins/installed.html.haml
@@ -1,7 +1,5 @@
 - page_title t('.page_title')
 
--# TODO: should more blush up this page
-
 %table{class: "table table-striped table-hover", id: "plugins-table"}
   %thead
     %tr