class ActionCable::Server::Configuration

in a Rails config initializer.
An instance of this configuration object is available via ActionCable.server.config, which allows you to tweak Action Cable configuration

def initialize

def initialize
  @log_tags = []
  @connection_class = -> { ActionCable::Connection::Base }
  @worker_pool_size = 4
  @disable_request_forgery_protection = false
  @allow_same_origin_as_host = true
end

def pubsub_adapter

Also makes sure proper dependencies are required.
If the adapter cannot be found, this will default to the Redis adapter.
Returns constant of subscription adapter specified in config/cable.yml.
def pubsub_adapter
  adapter = (cable.fetch("adapter") { "redis" })
  # Require the adapter itself and give useful feedback about
  #   1. Missing adapter gems and
  #   2. Adapter gems' missing dependencies.
  path_to_adapter = "action_cable/subscription_adapter/#{adapter}"
  begin
    require path_to_adapter
  rescue LoadError => e
    # We couldn't require the adapter itself. Raise an exception that
    # points out config typos and missing gems.
    if e.path == path_to_adapter
      # We can assume that a non-builtin adapter was specified, so it's
      # either misspelled or missing from Gemfile.
      raise e.class, "Could not load the '#{adapter}' Action Cable pubsub adapter. Ensure that the adapter is spelled correctly in config/cable.yml and that you've added the necessary adapter gem to your Gemfile.", e.backtrace
    # Bubbled up from the adapter require. Prefix the exception message
    # with some guidance about how to address it and reraise.
    else
      raise e.class, "Error loading the '#{adapter}' Action Cable pubsub adapter. Missing a gem it depends on? #{e.message}", e.backtrace
    end
  end
  adapter = adapter.camelize
  adapter = "PostgreSQL" if adapter == "Postgresql"
  "ActionCable::SubscriptionAdapter::#{adapter}".constantize
end