Send email asynchroniously using Sidekiq.

Create your mailer us usual:

# app/mailers/users_mailer.rb

class UsersMailer < ActionMailer::Base

def welcome_email(user_id)
    @user = User.find(user_id)

    mail(   :to      => @user.email,
            :subject => "Welcome"
    ) do |format|
      format.text
      format.html
    end
  end
end

Send email:

user = User.find(1)

mail = UsersMailer.welcome_email(user.id)
#mail.deliver_now
mail.deliver_later

    

Gemfile:

gem 'sidekiq'

Redis provides data storage for Sidekiq. It holds all the job data along with runtime and historical data

To make work mailer.deliver_later we need to tell ActiveJob to use Sidekiq:

# config/initializers/active_job.rb

ActiveJob::Base.queue_adapter = :sidekiq

As long as Active Job is setup to use Sidekiq we can use #deliver_later:

# config/environments/development.rb

Rails.application.configure do
  ...
  
  config.active_job.queue_adapter = :sidekiq
  
  config.action_mailer.perform_deliveries = true
  config.action_mailer.raise_delivery_errors = true

  config.action_mailer.delivery_method = :smtp
  
  config.action_mailer.smtp_settings = { ... }
  

end

Read more about ActionJob and Sidekiq: https://github.com/mperham/sidekiq/wiki/Active-Job

config/sidekiq.yml:

---
:concurrency: 1
:queues:
  - default
  - mailers

Specify queue name for different environments:

# config/initializers/sidekiq.rb

Sidekiq.configure_server do |config|
  config.redis = { url: 'redis://localhost:6379/0', namespace: "mysite_sidekiq_#{Rails.env}" }
end

Sidekiq.configure_client do |config|
  config.redis = { url: 'redis://localhost:6379/0', namespace: "mysite_sidekiq_#{Rails.env}" }
end

bundle exec sidekiq --environment development -C config/sidekiq.yml 

Use god for monitoring and running sidekiq automatically: https://gist.github.com/maxivak/05847dc7f558d5ef282e

Read this: https://github.com/mperham/sidekiq/wiki/Devise

test environment:

# config/environments/test.rb

Rails.application.configure do
 ...
 

spec/rails_helper.rb:

# sidekiq
require 'sidekiq/testing'
Sidekiq::Testing.fake!  # by default it is fake

User Sidekiq::Worker.jobs.size to see the number of jobs in the queue.

Test that email was enqueued:

RSpec.describe "Test sending email with sidekiq", :type => :request do

  it 'send email to sidekiq' do
   
    expect{
      user = User.first
      mail = UsersMailer.welcome_email(user.id)
      mail.deliver_later
    }.to change( Sidekiq::Worker.jobs, :size).by(1)

  end

end