Update rails, gems, use MathJax over CDN

config/environments/development.rb

@@ -13,12 +13,13 @@ Rails.application.configure do
   config.consider_all_requests_local = true
 
   # Enable/disable caching. By default caching is disabled.
-  if Rails.root.join('tmp/caching-dev.txt').exist?
+  # Run rails dev:cache to toggle caching.
+  if Rails.root.join('tmp', 'caching-dev.txt').exist?
     config.action_controller.perform_caching = true
 
     config.cache_store = :memory_store
     config.public_file_server.headers = {
-      'Cache-Control' => "public, max-age=#{2.days.seconds.to_i}"
+      'Cache-Control' => "public, max-age=#{2.days.to_i}"
     }
   else
     config.action_controller.perform_caching = false
@@ -26,6 +27,9 @@ Rails.application.configure do
     config.cache_store = :null_store
   end
 
+  # Store uploaded files on the local file system (see config/storage.yml for options)
+  config.active_storage.service = :local
+
   # Don't care if the mailer can't send.
   config.action_mailer.raise_delivery_errors = false
 
@@ -37,6 +41,9 @@ Rails.application.configure do
   # Raise an error on page load if there are pending migrations.
   config.active_record.migration_error = :page_load
 
+  # Highlight code that triggered database queries in logs.
+  config.active_record.verbose_query_logs = true
+
   # Debug mode disables concatenation and preprocessing of assets.
   # This option may cause significant delays in view rendering with a large
   # number of complex assets.

config/environments/production.rb

@@ -14,10 +14,9 @@ Rails.application.configure do
   config.consider_all_requests_local       = false
   config.action_controller.perform_caching = true
 
-  # Attempt to read encrypted secrets from `config/secrets.yml.enc`.
-  # Requires an encryption key in `ENV["RAILS_MASTER_KEY"]` or
-  # `config/secrets.yml.key`.
-  config.read_encrypted_secrets = true
+  # Ensures that a master key has been made available in either ENV["RAILS_MASTER_KEY"]
+  # or in config/master.key. This key is used to decrypt credentials (and other encrypted files).
+  config.require_master_key = true
 
   # Disable serving static files from the `/public` folder by default since
   # Apache or NGINX already handles this.
@@ -30,8 +29,6 @@ Rails.application.configure do
   # Do not fallback to assets pipeline if a precompiled asset is missed.
   config.assets.compile = false
 
-  config.assets.digest = true
-
   # `config.assets.precompile` and `config.assets.version` have moved to config/initializers/assets.rb
 
   # Enable serving of images, stylesheets, and JavaScripts from an asset server.
@@ -41,6 +38,9 @@ Rails.application.configure do
   # 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'
@@ -62,6 +62,7 @@ Rails.application.configure do
   # Use a real queuing backend for Active Job (and separate queues per environment)
   # config.active_job.queue_adapter     = :resque
   # config.active_job.queue_name_prefix = "projekteuler_#{Rails.env}"
+
   config.action_mailer.perform_caching = false
 
   # Ignore bad email addresses and do not raise email delivery errors.

config/environments/test.rb

@@ -15,7 +15,7 @@ Rails.application.configure do
   # Configure public file server for tests with Cache-Control for performance.
   config.public_file_server.enabled = true
   config.public_file_server.headers = {
-    'Cache-Control' => "public, max-age=#{1.hour.seconds.to_i}"
+    'Cache-Control' => "public, max-age=#{1.hour.to_i}"
   }
 
   # Show full error reports and disable caching.
@@ -27,6 +27,10 @@ Rails.application.configure do
 
   # Disable request forgery protection in test environment.
   config.action_controller.allow_forgery_protection = false
+
+  # Store uploaded files on the local file system in a temporary directory
+  config.active_storage.service = :test
+
   config.action_mailer.perform_caching = false
 
   # Tell Action Mailer not to deliver emails to the real world.