Add notation for permission on in_tail setting page

app/controllers/application_controller.rb

@@ -5,7 +5,7 @@ class ApplicationController < ActionController::Base
   helper_method :current_user
   helper_method :current_locale
   helper_method :installing_gem?, :installing_gems, :uninstalling_gem?, :uninstalling_gems
-  helper_method :fluentd_ui_title, :fluentd_ui_brand
+  helper_method :fluentd_ui_title, :fluentd_ui_brand, :fluentd_run_user
   helper_method :file_tail
   helper_method :fluentd_exists?
   before_action :login_required
@@ -38,6 +38,10 @@ class ApplicationController < ActionController::Base
     ENV["FLUENTD_UI_BRAND"] || "fluentd"
   end
 
+  def fluentd_run_user
+    Fluentd.instance.td_agent? ? "td-agent" : ENV["USER"]
+  end
+
   def installing_gem?
     installing_gems.present?
   end

app/views/fluentd/settings/in_tail/show.html.haml

@@ -2,3 +2,4 @@
 
 = render partial: "shared/vue/treeview", locals: {name: "path", action: after_file_choose_daemon_setting_in_tail_path(@fluentd), submit_button: t('terms.next')}
 
+%p.text.text-danger= t('fluentd.settings.in_tail.notice_for_permission', user: fluentd_run_user)

config/locales/translation_en.yml

@@ -154,6 +154,7 @@ en:
       in_tail_option_guide: |
           For each config parameter, pelase refer to the <a href="http://docs.fluentd.org/articles/in_tail" target="_blank">Tail iutput plugin</a> documentation page.
       in_tail:
+        notice_for_permission: "Please check permission or group setting for %{user} user can read it."
         restart_from_first: Restart from first
         grok_manual: |
           <p>

config/locales/translation_ja.yml

@@ -155,6 +155,7 @@ ja:
         <a target="_blank" href="http://docs.fluentd.org/ja/articles/in_tail">in_tailプラグインの解説ページ</a>や
         <a target="_blank" href="http://fluentular.herokuapp.com/">Fluentular</a>もご参照ください。
       in_tail:
+        notice_for_permission: "※%{user}ユーザーが読み込み可能なようにパーミッションやグループの設定をご確認ください。"
         restart_from_first: 最初からやり直す
         grok_manual: |
           <p>