Redis Logging

app_config.rb

# config/initializers/app_config.rb

# An initializer that contains config stuff
# ...

class RedisConfig < Settingslogic
  source "#{Rails.root}/config/redis.yml"
  namespace Rails.env
end

# ...

redis.rb

# config/initializers/redis.rb

require 'redis'

# Monkey Patching for profit. The old way of doing this
# using method_missing added a little bit too much overhead.
# It also showed the commands out of order. This is more accurate.
class Redis
  class Client
    alias :old_initialize :initialize
    alias :old_logging :logging

    def initialize(options = {})
      old_initialize(options)
      @notification = options[:notification]
    end

    def logging(commands, &block)
      return old_logging(commands, &block) unless @notification

      ActiveSupport::Notifications.instrument('request.redis', commands: commands) do
        return old_logging(commands, &block)
      end
    end
  end
end

class RedisInstrumenter < ActiveSupport::LogSubscriber
  def request(event)
    return unless logger.debug?

    name = "%s (%.2fms)" % ["Redis", event.duration]
    cmds = event.payload[:commands]

    output = "  #{color(name, RED, true)}"

    cmds.each do |name, *args|
      if args.present?
        output << " [ #{name.to_s.upcase} #{args.join(" ")} ]"
      else
        output << " [ #{name.to_s.upcase} ]"
      end
    end

    debug output
  end
end

if Rails.env.development? || Rails.env.test?
  RedisInstrumenter.attach_to(:redis)
end

REDIS = Redis.new(RedisConfig)

redis.yml

# config/redis.yml

defaults: &defaults
  host: 127.0.0.1
  notification: true

development:
  <<: *defaults
  db: 0

test:
  <<: *defaults
  db: 1

production: