send mail to define emails when production app restarted

to emails from ENV

do not send mail if rails console started
wait 1 min and check before adding new job to avoid
duplicate email when all apps are restarted(passenger+worker)

app/jobs/app_restart_mail_job.rb

+class AppRestartMailJob < ActiveJob::Base
+  queue_as :default
+
+  def perform
+    AppRestartMailer.send_mail&.deliver_now
+  end
+end

app/mailers/app_restart_mailer.rb

+class AppRestartMailer < ActionMailer::Base
+  default from: ENV['DEVISE_SENDER'] || 'eln'
+
+  def text_content
+    "The application was restarted.\n#{revision}"
+  end
+
+  def revision
+    if File.exist?('../../revisions.log')
+      `tail -n 1 ../../revisions.log`
+    end
+  end
+
+  def send_mail
+    unless ENV['ADM_EMAILS'].blank?
+      mail(to: ENV['ADM_EMAILS'], subject: "Rails app restarted") do |format|
+        format.text { render plain: text_content }
+      end
+    end
+  end
+end

config/environments/production.rb

@@ -89,7 +89,11 @@ Rails.application.configure do
     :enable_starttls_auto => ENV['SMTP_TLS'] && ENV['SMTP_TLS'].match(/true/),
     :openssl_verify_mode  => ENV['SMTP_SSL_MODE']
   }
-  
-  config.browserify_rails.commandline_options = "-t [ babelify --presets [ es2015 react ] --plugins [ transform-object-rest-spread ] ]  -g uglifyify  -p bundle-collapser/plugin "
 
+  config.browserify_rails.commandline_options = "-t [ babelify --presets [ es2015 react ] --plugins [ transform-object-rest-spread ] ]  -g uglifyify  -p bundle-collapser/plugin "
+  unless defined?(Rails::Console)
+    config.after_initialize do
+      AppRestartMailJob.set(wait: 1.minute).perform_later if Delayed::Job.where("handler like ?", "%AppRestartMailJob%").empty?
+    end
+  end
 end