README.md

In case Redis is down, the job will be perform synchronously instead of crashing.

On your job, use perform_later_with_failover instead of perform_later.

Take this into account:

1. You should find a way to monitor that Redis/Sidekiq is down and be alerted. You will be in a degraded mode if the task are executed synchronously and you should be aware of this as soon as possible
2. You should use perform_later_with_failover only if you expect the execution time of the task to be fairly short (send email, slack notification, etc.) If you know the task requires time to be perform, it's not a good solution because your user's browser will be blocked.

active_job_with_failover.rb

# lib/active_job_with_failover.rb

class ActiveJob::Base
  # In case Redis is down, it will perform the job synchronously
  # Instead of crashing
  def self.perform_later_with_failover(*args)    
    redis_available = true
    Sidekiq.redis do |connection|
      begin
        connection.info
      rescue Redis::CannotConnectError
        redis_available = false
      end
    end
    if redis_available || Rails.application.config.active_job.queue_adapter == :test
      # process the job asynchronously
      perform_later(*args)
    else
      # otherwise, instantiate and perform synchronously
      perform_now(*args)
    end
  end
end

environment.rb

# Add the following line in config/environment.rb
require 'active_job_with_failover'