Verk should be able to start even if Redis connection is not available

[edgurgel]

Verk should be able to start even if Redis connection is not available

[edgurgel]

Yeah, I agree that Verk should be able to start without Redis and keep retrying to reconnect etc. Your solution seems to be the way to go 👍

[lpil]

I'm unsure about this one. Given the init callback is about making guarantees about the readiness of the system should we consider Werk ready if it does not have a connected Redis instance? It seems like a fairly fundamental dependancy.

[keyan]

@lpil I understand your point and perhaps we should just leave it at that.

It might help to explain where I hit this issue at first. I have a webserver which has added Verk to its supervision tree but only uses Verk to enqueue tasks to Redis in the Resque/Verk format. There is a separate processor application that is responsible for dequeueing and processing those tasks. While I understand why it makes sense for the processor to crash if it cannot cannot to Redis, I would rather the webserver be able to start and serve traffic while it continues to retry connecting.

Maybe the premise is flawed here? It might be non-standard usage of the library and thus it doesn't make sense to build around support for the use case. I am not sure.

[lpil]

It seems that Verk doesn't require the application to be started in order to enqueue a job.

verk/lib/verk.ex

Lines 53 to 59 in d0f07c1

	def enqueue(%Job{jid: jid, queue: queue} = job, redis) do
	job = %Job{job | enqueued_at: Time.now |> DateTime.to_unix}
	case Redix.command(redis, ["LPUSH", "queue:#{queue}", Poison.encode!(job)]) do
	{:ok, _} -> {:ok, jid}
	{:error, reason} -> {:error, reason}
	end
	end

You could just call that function and pass in the pid/atom of your own Redis instance. :)

[edgurgel]

@keyan for your specific use case you could pass a connection to Verk.enqueue. So simply handling the connection on your side would do the job.

def enqueue(job, redis \ Verk.Redis)

Ok so Verk supports losing connectivity with Redis after it has started but it won't start without it.

I'm not sure if this "inconsistency" is bad or good...

[lpil]

I've been doing some thinking and reading and I think that now I agree with you. Werk can reasonably guarantee that it is in a state where it could accept jobs, though not that it has somewhere to accept them from. :)