Overview

The grape-throttle gem provides a simple endpoint-specific throttling mechanism for Grape.

Requirements

• Grape >= 0.10.0
• Redis

Usage

Build and Install

To use, just install the gem from RubyGems or via Bundler by requiring it in your Gemfile.

gem 'grape-throttle'

Middleware Setup

Then in your Grape API, install the middleware which will do the throttling. At a minimum, it requires a Redis instance for caching as the cache parameter.

Simple Case

use Grape::Middleware::ThrottleMiddleware, cache: Redis.new

In this simple case, you just set up the middleware, and pass it a Redis instance.

Advanced Case

use Grape::Middleware::ThrottleMiddleware, cache: $redis, user_key: ->(env) do
  # Use the current_user's id as an identifier
  user = current_user
  user.nil? ? nil : user.id
end

In this more advanced case, the Redis instance is in the global variable $redis.

The user_key parameter is a function that can be used to determine a custom identifier for a user. This key is used to form the Redis key to identify this user uniquely. It defaults to the IP address. The env parameter given to the function is the Rack environment and can be used to determine information about the caller.

Logging

The gem will log errors to STDOUT by default. If you prefer a different logger you can use the logger option to pass in your own logger.

use Grape::Middleware::ThrottleMiddleware, cache: Redis.new, logger: Logger.new('my_custom_log.log')

Endpoint Usage

This gem adds a throttle DSL-like method that can be used to throttle different endpoints differently.

The throttle method takes a Hash of the period to throttle, and the maximum allowed hits. After the maximum, the middleware throws an error with Grape's error! function.

Supported predefined periods are: :hourly, :daily, :monthly.

Example:

class API < Grape::API
  resources :users do

    # Allow start of competition only every 10 minutes
    desc "Start competition"
    throttle period: 10.minutes, limit: 1
    params do
      requires :id, type: Integer, desc: "id"
    end
    post "/:id/competition" do
      User.find(params[:id]).start_competition
    end

    # 3 times a day max
    desc "Fetch a user"
    throttle daily: 3
    params do
      requires :id, type: Integer, desc: "id"
    end
    get "/:id" do
      User.find(params[:id])
    end

    # Once a month or the user will go crazy
    desc "Poke a user"
    throttle monthly: 1
    params do
      requires :id, type: Integer, desc: "id"
    end
    post "/:id/poke" do
      User.find(params[:id]).poke
    end

    # No limit to the amount we can annoy users
    desc "Annoy a user"
    params do
      requires :id, type: Integer, desc: "id"
    end
    post "/:id/annoy" do
      User.find(params[:id]).annoy
    end
  end
end

TODO

• Custom error handling and error strings, status etc.
• Allow use of something other than Redis for caching

Thanks

Thanks to the awesome Grape community, and to @dblock for all the help getting this thing going.