Ability to express cron schedule using fugit natural language parser

[jgrau]

Hi Ben

First of all thank you for good_job 🙏 It's been running rock solid and I've recently migrated all my Kubernetes cron-jobs to good_job recurring tasks.

Question: Would you accept a pull request that made it possible to use the fugit natural language parser? Without having given it a lot of thought we could check in next_at whether cron is already an instance of Fugit::Cron. That way, in the schedule configuration you could do:

config.good_job.cron = {
  # Every 15 minutes, enqueue `ExampleJob.set(priority: -10).perform_later(42, name: "Alice")`
  frequent_task: { # each recurring job must have a unique key
    cron: Fugit::Nat.parse('every day at five'),
    class: "ExampleJob", # reference the Job class with a string
    args: [42, { name: "Alice" }], # arguments to pass; can also be a proc e.g. `-> { { when: Time.now } }`
    set: { priority: -10 }, # additional ActiveJob properties; can also be a lambda/proc e.g. `-> { { priority: [1,2].sample } }`
    description: "Something helpful", # optional description that appears in Dashboard (coming soon!)
  },
  another_task: {
    cron: "0 0,12 * * *",
    class: "AnotherJob",
  },
  # etc.
}

I realise it would couple the gem more tightly to fugit so I can totally understand if you feel the benefits are not worth it. :)

[bensheldon]

@jgrau yay! I'm really happy to know GoodJob is working out for you! 🎉

Would you accept a pull request that made it possible to use the fugit natural language parser? Without having given it a lot of thought we could check in next_at whether cron is already an instance of Fugit::Cron.

That sounds good to me 👍 I think it would involve two changes:

1. Updating this method:

   good_job/lib/good_job/cron_entry.rb

   Lines 44 to 47 in 5df2c05

   	def next_at
   	fugit = Fugit::Cron.parse(cron)
   	fugit.next_time.to_t
   	end

2. The logic to display the cron param in the Dashboard (maybe a #display_cron method)

(I could also imagine the cron param taking any object that responds to #next_time but let's consider that YAGNI for now)