Update app files to Rails 6.1 defaults.

config/environments/production.rb

@@ -1,3 +1,5 @@
+require "active_support/core_ext/integer/time"
+
 Rails.application.configure do
   # Settings specified here will take precedence over those in config/application.rb.
 
@@ -22,36 +24,22 @@ Rails.application.configure do
   # Apache or NGINX already handles this.
   config.public_file_server.enabled = ENV['RAILS_SERVE_STATIC_FILES'].present?
 
-  # Compress CSS using a preprocessor.
-  # config.assets.css_compressor = :sass
-
-  # Do not fallback to assets pipeline if a precompiled asset is missed.
-  # config.assets.compile = false
-
   # Enable serving of images, stylesheets, and JavaScripts from an asset server.
-  # config.action_controller.asset_host = 'http://assets.example.com'
+  # config.asset_host = 'http://assets.example.com'
 
   # Specifies the header that your server uses for sending files.
   # config.action_dispatch.x_sendfile_header = 'X-Sendfile' # for Apache
   # config.action_dispatch.x_sendfile_header = 'X-Accel-Redirect' # for NGINX
 
-  # Store uploaded files on the local file system (see config/storage.yml for options).
-  # config.active_storage.service = :local
-
-  # Mount Action Cable outside main process or domain.
-  # config.action_cable.mount_path = nil
-  # config.action_cable.url = 'wss://example.com/cable'
-  # config.action_cable.allowed_request_origins = [ 'http://example.com', /http:\/\/example.*/ ]
-
   # Force all access to the app over SSL, use Strict-Transport-Security, and use secure cookies.
   # config.force_ssl = true
 
-  # Use the lowest log level to ensure availability of diagnostic information
-  # when problems arise.
+  # Include generic and useful information about system operation, but avoid logging too much
+  # information to avoid inadvertent exposure of personally identifiable information (PII).
   config.log_level = :error
 
   # Prepend all log lines with the following tags.
-  config.log_tags = [:request_id]
+  config.log_tags = [ :request_id ]
 
   # Use a different cache store in production.
   # config.cache_store = :mem_cache_store
@@ -70,16 +58,22 @@ Rails.application.configure do
 
   # Enable locale fallbacks for I18n (makes lookups for any locale fall back to
   # the I18n.default_locale when a translation cannot be found).
-  config.i18n.fallbacks = [I18n.default_locale]
+  config.i18n.fallbacks = true
 
   # Send deprecation notices to registered listeners.
   config.active_support.deprecation = :notify
 
+  # Log disallowed deprecations.
+  config.active_support.disallowed_deprecation = :log
+
+  # Tell Active Support which deprecation messages to disallow.
+  config.active_support.disallowed_deprecation_warnings = []
+
   # Use default logging formatter so that PID and timestamp are not suppressed.
   config.log_formatter = ::Logger::Formatter.new
 
   # Use a different logger for distributed setups.
-  # require 'syslog/logger'
+  # require "syslog/logger"
   # config.logger = ActiveSupport::TaggedLogging.new(Syslog::Logger.new 'app-name')
 
   if ENV["RAILS_LOG_TO_STDOUT"].present?