rate_limit

Applies a rate limit to all actions or those specified by the normal `before_action` filters with `only:` and `except:`.

The maximum number of requests allowed is specified `to:` and constrained to the window of time given by `within:`.

Rate limits are by default unique to the ip address making the request, but you can provide your own identity function by passing a callable in the `by:` parameter. It’s evaluated within the context of the controller processing the request.

Requests that exceed the rate limit are refused with a `429 Too Many Requests` response. You can specialize this by passing a callable in the `with:` parameter. It’s evaluated within the context of the controller processing the request.

Rate limiting relies on a backing `ActiveSupport::Cache` store and defaults to `config.action_controller.cache_store`, which itself defaults to the global `config.cache_store`. If you don’t want to store rate limits in the same datastore as your general caches, you can pass a custom store in the `store` parameter.

Examples:

class SessionsController < ApplicationController
  rate_limit to: 10, within: 3.minutes, only: :create
end

class SignupsController < ApplicationController
  rate_limit to: 1000, within: 10.seconds,
    by: -> { request.domain }, with: -> { redirect_to busy_controller_url, alert: "Too many signups on domain!" }, only: :new
end

class APIController < ApplicationController
  RATE_LIMIT_STORE = ActiveSupport::Cache::RedisCacheStore.new(url: ENV["REDIS_URL"])
  rate_limit to: 10, within: 3.minutes, store: RATE_LIMIT_STORE
end