ActionCableSubscriptionAdapter

Implements a configuration option that allows you to inject any Redis client for ActionCable to use in its SubscriptionAdapter.

This is useful if you use something like Redis::Namespace which needs to be configured with a Redis URL and Namespace name usually coming from ENV vars. Rail's cable.yml is insufficient for this because it only allows URL configuration of the Redis client. You can also use this gem if you're using distributed Redis with Makara.

Installation

Add this line to your application's Gemfile:

gem 'action_cable_subscription_adapter'

And then execute:

$ bundle

Or install it yourself as:

$ gem install action_cable_subscription_adapter

Usage

Set the custom_adapter in the adapter option in config/cable.yml

development:
  adapter: custom_adapter

test:
  adapter: async

production:
  adapter: custom_adapter

The custom_adapter will make ActionCable load this gem's SubscriptionAdapter rather than the Rails built in one. Then...

Create an initializer and set your custom Redis client. Example:

# config/initializers/action_cable_subscription_adapter.rb

ActionCableSubscriptionAdapter.config do |c|
  c.redis_connector = MyRedisClient.new your: "options"
end

You can also assign a proc to c.redis_connector:

ActionCableSubscriptionAdapter.config do |c|
  c.redis_connector = ->(subscription_adapter) { MyRedisClient.new your: "options" }
end

Custom Redis Client

The custom Redis client needs to conform to the redis-rb gem's API.

Redis::Namespace

In the case of Redis::Namespace you have to stream_from the namespaced channel. In your channel object where you declare stream_from do something like this:

class YourChannel < ApplicationCable::Channel
  def subscribed
    stream_from "your_namespace:your_channel"
  end
end

Multiprocess Servers

If you're using a multiprocess server such as Puma or Unicorn you need to create a new instance of the Redis client by using a proc for the redis_connector. Example:

ActionCableSubscriptionAdapter.config do |c|
  c.redis_connector = ->(*) { Redis::Namespace.new REDIS_NAMESPACE, redis: Redis.new(url: REDIS_URL) }
end

Since ActionCable runs in threads, each thread will call redis_connector when subscribing to the channel. Using a proc in this way means a new instance of the Redis client will connect in each thread and therefore each redis client instance will have its own TCP socket.

Development

After checking out the repo, run bin/setup to install dependencies. You can also run bin/console for an interactive prompt that will allow you to experiment.

To install this gem onto your local machine, run bundle exec rake install. To release a new version, update the version number in version.rb, and then run bundle exec rake release, which will create a git tag for the version, push git commits and tags, and push the .gem file to rubygems.org.

Contributing

Bug reports and pull requests are welcome on GitHub at https://github.com/DiegoSalazar/action_cable_subscription_adapter.