ActionController::RoutingError No route matches [GET] & [OPTION] for "/cloudfoundryapplication" - ruby-on-rails

Question

I am running Rails 5.1.3 with Puma on Pivotal Web Services. Since upgrading to this version from Rails 4, i am seeing the following errors appear in the logs:
1. ActionController::RoutingError (No route matches [GET] "/cloudfoundryapplication")
2. ActionController::RoutingError (No route matches [OPTION] "/cloudfoundryapplication")
I can't find any details on the "/cloudfoundryapplication" on Pivotal but as it an external application i figured it might be related to Cross-Origin Resource Sharing (CORS). I then used the 'rack-cors' gem to try to fix the issue. The effect was that the [OPTION] errors disappeared but not the [GET] errors.
Here is my config/application.rb:
require_relative 'boot'
require "rails"
# Pick the frameworks you want:
require "active_model/railtie"
require "active_job/railtie"
require "action_controller/railtie"
require "action_mailer/railtie"
require "action_view/railtie"
require "sprockets/railtie"
require "rails/test_unit/railtie"
require 'pdfkit'
# Require the gems listed in Gemfile, including any gems
# you've limited to :test, :development, or :production.
Bundler.require(*Rails.groups)
module MyFaro
class Application < Rails::Application
# Initialize configuration defaults for originally generated Rails version.
config.load_defaults 5.1
# Settings in config/environments/* take precedence over those specified here.
# Application configuration should go into files in config/initializers
# -- all .rb files in that directory are automatically loaded.
# Set Time.zone default to the specified zone and make Active Record auto-convert to this zone.
# Run "rake -D time" for a list of tasks for finding time zone names. Default is UTC.
config.time_zone = 'Brussels'
# The default locale is :en and all translations from config/locales/*.rb,yml are auto loaded.
#config.i18n.load_path = Dir[Rails.root.join('config', 'locales', '*.{rb,yml}').to_s]
config.i18n.default_locale = :nl
#config.skylight.probes += %w(mongoid mongo)
config.middleware.use PDFKit::Middleware, {:print_media_type => true}, :only => %r[/print_story]
config.after_initialize do
ApplicationController.helpers.cache_set_look_up_hash
ApplicationController.helpers.cache_set_system_parameter_hash
end
end
end
and my config/environments/production.rb:
Rails.application.configure do
# Settings specified here will take precedence over those in config/application.rb.
#CORS
config.middleware.insert_before 0, Rack::Cors do
allow do
origins '*'
resource '*', :headers => :any, :methods => [:get, :post, :options]
end
end
# Code is not reloaded between requests.
config.cache_classes = true
# Eager load code on boot. This eager loads most of Rails and
# your application in memory, allowing both threaded web servers
# and those relying on copy on write to perform better.
# Rake tasks automatically ignore this option for performance.
config.eager_load = true
# Full error reports are disabled and caching is turned on.
config.consider_all_requests_local = false
config.action_controller.perform_caching = true
config.cache_store = :memory_store
# 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
# Disable serving static files from the `/public` folder by default since
# Apache or NGINX already handles this.
config.public_file_server.enabled = true
# Compress JavaScripts and CSS.
config.assets.js_compressor = :uglifier
# config.assets.css_compressor = :sass
# Do not fallback to assets pipeline if a precompiled asset is missed.
config.assets.compile = 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.
# config.action_controller.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
# 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.
config.log_level = :error
# Prepend all log lines with the following tags.
config.log_tags = [ :request_id ]
# Use a different cache store in production.
# config.cache_store = :mem_cache_store
# 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 = "my_faro_#{Rails.env}"
config.action_mailer.perform_caching = false
# Ignore bad email addresses and do not raise email delivery errors.
# Set this to true and configure the email server for immediate delivery to raise delivery errors.
config.action_mailer.raise_delivery_errors = true
config.action_mailer.perform_deliveries = true
config.action_mailer.default_url_options = { host: 'http://myfaro.cfapps.io/'}
config.action_mailer.delivery_method = :smtp
config.action_mailer.smtp_settings = {
address: 'smtp.mailgun.org',
port: 587,
authentication: 'plain',
#domain: 'sandboxe3e6f1cfc3d34efc8dba23c1a1eaff8b.mailgun.org',
domain: 'mg.myfaro.be',
#user_name: 'postmaster#sandboxe3e6f1cfc3d34efc8dba23c1a1eaff8b.mailgun.org',
user_name: 'postmaster#mg.myfaro.be',
#password: '25c695256391ca3e9f6c6bb1dd9f622f'
password: 'f1d6d58994362f084cc2ecac0e46256c'
}
# 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 = true
config.i18n.available_locales = [:en,:nl,:fr,:de]
# Send deprecation notices to registered listeners.
config.active_support.deprecation = :notify
# 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'
# config.logger = ActiveSupport::TaggedLogging.new(Syslog::Logger.new 'app-name')
if ENV["RAILS_LOG_TO_STDOUT"].present?
logger = ActiveSupport::Logger.new(STDOUT)
logger.formatter = config.log_formatter
config.logger = ActiveSupport::TaggedLogging.new(logger)
end
end

Answer 1

I got an answer from the Pivotal support team.
Pivotal Web Services' Apps Manager uses the /cloudfoundryapplication endpoint as the root for Spring Boot Actuator integrations. It calls this endpoint for an app when you view the app in the Apps Manager UI, regardless of whether you have configured Spring Boot Actuator endpoints for Apps Manager.
So for applications not using the Spring Boot Actuator endpoints these errors appear but only while using the Apps Manager GUI.
Its like Schrodingers Cat of the Light in the Fridge: if you don't look, the errors don't appear. I checked the logs via the CLI and indeed there are no errors at all.

Answer 2

Borrowing a line from an app's config/routes.rb:
match '/cloudfoundryapplication', to: proc { [200, {}, ['']] }, via: %i[get options]