Allow configuration of ActionMailer queue name

[chrismcg]

Currently all mails sent with deliver_later are put on the mailers queue. This patch keeps that default but allows the queue name to be configured globally.

The motivation was trying to use https://github.com/chanks/que as the queuing backend. It's a good fit for a simple queue for a single dyno heroku app but by default only listens to one queue per application. As ActiveJob will use the default queue and ActionMailer the mailers queue jobs wouldn't get run.

The Que library might change to support more than one queue but in the meantime this will allow Rails to work with it. It will also be useful for users of other backends who might need to change where mails are queued.

[vipulnsward]

Whats this for?

[chrismcg]

For testing I could set the configuration separately from using it.

[senny]

We need to configure the default AM queue as well in Queue Classic.

[mandrews]

+1

[cristianbica]

I'm thinking of a cleaner approach. ActiveJob::Base accepts a Proc for the queue_as and that proc is executed when trying to enqueue the job so we can leverage that:

  class DeliveryJob < ActiveJob::Base # :nodoc:
    queue_as do
      ActionMailer::Base. deliver_later_queue_name || :mailers
    end
  end

what do you think @chrismcg?

[senny]

@cristianbica I'm not sure I understand the benefit of that approach. Why not set :mailers as the default for that option? This way you can at least use introspection on deliver_later_queue_name to see where the jobs are going. Otherwise the default is hidden away.

[cristianbica]

@senny yeah the || :mailers makes no sense here but my main suggesting was to keep defining the deliver_later_queue_name on ActionMailer base use use that in the DeliveryJob's queue_as. In this PR implementation the queue name is set in the MessageDelivery wrapper.

[senny]

@cristianbica 👍 got it.

[chrismcg]

@cristianbica sorry, I've only just seen your comment. I didn't know you could use a proc there so I'll have a look at it later in the week when I've a bit more time.

[jakegavin]

+1
Just came across this while upgrading to 4.2. This would be nice to have. Thanks for working on it.

[chrismcg]

@cristianbica finally got around to doing that change. I think it's clearer this way.

[cristianbica]

Please squash your commits. Otherwise seems good to me.

[chrismcg]

Commits squashed, thanks!

[michaelsauter]

Is there a specific reason why this didn't make it into 4.2.4?

Judging by this PR, I thought it would be included since this has been merged on June 3, but 4.2.4 wasn't released until August 24.

[matthewd]

@michaelsauter new features aren't backported to bugfix releases.

[michaelsauter]

@matthewd Ah okay, thanks. Though I think this almost counts as a bugfix ;)

[rossinkiwi]

I'm trying to set up separate mailer queues for transaction mail processing and bulk mail processing in my Rails 5.1.3 application. I was hoping to be able to designate the queue by setting the deliver_later_queue_name for each of my inherited ActionMailer's:

class ApplicationMailer < ActionMailer::Base
end

class UserMailer < ApplicationMailer  self.deliver_later_queue_name = 'mail'
  self.deliver_later_queue_name = 'mail'
  self.smtp_settings = {
    address: "smtp.sendgrid.net",
    port: 587,
    ...
}

class BulkMailer < ApplicationMailer
  self.deliver_later_queue_name = 'bulkmail'
  self.smtp_settings = {
    address: "email-smtp.us-west-2.amazonaws.com",
    port: 587,
    ...
  }

This works fine for the smtp_settings, but the deliver_later_queue_name appears to be a class variable? and so when I set it in the BulkMailer or UserMailer, it changes it for all the ActionMailer's.

Is there a way for me to set separate deliver_later_queue_name's for my BulkMailer and UserMailer?

[JamesLivengood]

Also curious about @rossinkiwi 's question