add Dockerfile and configure production app

config/boot.rb

@@ -2,5 +2,27 @@
 
 ENV['BUNDLE_GEMFILE'] ||= File.expand_path('../Gemfile', __dir__)
 
+if ENV['RAILS_ENV'] == 'production' && ENV['SECRET_KEY_BASE'].to_s.empty?
+  require 'dotenv'
+  require 'securerandom'
+
+  dotenv_path = './docuseal.env'
+
+  unless File.exist?(dotenv_path)
+    default_env = <<~TEXT
+      DATABASE_URL= # keep empty to use sqlite or specify postgresql database URL
+      SECRET_KEY_BASE=#{SecureRandom.hex(64)}
+    TEXT
+
+    File.write(dotenv_path, default_env)
+  end
+
+  database_url = ENV.fetch('DATABASE_URL', nil)
+
+  Dotenv.load(dotenv_path)
+
+  ENV['DATABASE_URL'] = ENV['DATABASE_URL'].to_s.empty? ? database_url : ENV.fetch('DATABASE_URL', nil)
+end
+
 require 'bundler/setup' # Set up gems listed in the Gemfile.
 require 'bootsnap/setup' # Speed up boot time by caching expensive operations.