I'm new to Rails so I'm not sure if this is a stupid question but...
I have to run regular tasks to populate data to my Rails app. Today I use the whenever gem to create Cron entries to run these tasks on my system. I want to migrate my Rails app to Docker so that I can scale it more easily. I know that in Drupal(PHP) there is Poorman's Cron which uses requests to drive schedules.
Is there a way to implement scheduling inside Rails without using Cron or a better way of managing regular tasks that works well with Rails?
Yes, I created https://github.com/Ebbe/arask to keep stuff simple.
No need to install anything (other than the gem) or setup anything outside of rails. No background process, except for the actual job.
Add gem 'arask' to your Gemfile, run bundle install, rails generate arask:install and rails db:migrate.
Now you can setup your tasks in the file config/initializers/arask.rb:
arask.create script: 'puts "IM ALIVE!"', interval: :daily
arask.create task: 'my:awesome_task', interval: :hourly
arask.create task: 'my:other_awesome_task', interval: 2.hours
The tasks will automatically run if the server is running.
Is there a way to implement scheduling inside Rails without using Cron
or a better way of managing regular tasks that works well with Rails?
Cron is pretty much the go to tool for running scheduled activities on *nix system and most gems actually leverage cron under the hood, in fact avoiding cron is probably a lot more work unless you want to use a third party service.
One of the new features of Rails 5 is ActiveJob:
Active Job is a framework for declaring jobs and making them run on a
variety of queuing backends. These jobs can be everything from
regularly scheduled clean-ups, to billing charges, to mailings.
Anything that can be chopped up into small units of work and run in
parallel, really.
It can be used with several backends:
Sidekiq
Resque
Sucker Punch
Queue Classic
Related
I am on Rails 4 using the Resque Scheduler gem.
I am also using the sitemap generator gem in order to dynamically generate my sitemap.
I am having trouble figuring out the best way to schedule a rake task with resque scheduler. The sitemap generator recommends whenever, but I am assuming resque scheduler can accomplish the same thing (don't want to install another gem if I don't have to).
Does anyone know how to set this up?
I would like to run rake sitemap:refresh:no_ping every 5 hours.
I was thinking I would just schedule a background job and run it from there:
# resque_schedule.yml
update_sitemap:
every: 5h
class: "SitemapUpdater"
description: "This job refreshes the sitemap"
# sitemap_updater.rb
class SitemapUpdater
#queue = :sitemap_queue
def self.perform
# run rake task here
end
end
... however, I'm not sure if this is a good practice. Any advice would be much appreciated.
I don't see a problem with your approach, you just must be aware that the scheduler is reset during every deployment, so if you do frequent deploys, your scheduled jobs might be run later or even not run at all, as documented:
IMPORTANT: Rufus every syntax will calculate jobs scheduling time starting from the moment of deploy, resulting in resetting schedule time on every deploy, so it's probably a good idea to use it only for frequent jobs (like every 10-30 minutes), otherwise - when you use something like every 20h and deploy once-twice per day - it will schedule the job for 20 hours from deploy, resulting in a job to never be run.
You might also run the rake from system cron itself, which is an even more lightweight solution as it requires no scheduler gems at all, just the rake task, and will be scheduled reliably in time.
See e.g. this answer for setting up the "every 5 hours" frequency in crontab and you might also need to study RVM wrappers if you use RVM for your ruby project (you must call rake using the RVM wrappers in such case, e.g. call /home/deploy/.rvm/wrappers/ruby-2.3.0#mygemset/rake instead of just rake).
I'm trying to use cron in my application to send mails every week but I think it doesn't work on Windows.
Does anybody knows any equivalent to cron solution that works on Windows?
Windows equivalent of Unix's cron is a "Task Scheduler". You can configure your periodical task there.
Purely Ruby solution
If you want a purely Ruby solution look into:
rufus-scheduler - it's Windows cron gem.
crono - it's a in-Rails cron scheduler, so it should work anywhere.
Web services - there are plenty of free online services that would make a request to a given URL in specific time periods. This is basically a poor man's cronjob.
I recommend taking a look at Resque and the extension Resque-scheduler gems. You will need to have a resque scheduler process running with bundle exec rake resque:scheduler and at least one worker process running with QUEUE=* bundle exec rake resque:work.
If you want these services to run in the background as a windows service, you can do it with srvany.exe as described in this SO question.
The above assumes you are ok with installing Redis - a key-value store that is very popular among the Rails community as it can be easily used to support other Rails components such as caching and ActionCable, and it is awesome by itself for many multi-process use cases.
Resque is a queue system on top of Redis that allows you to define jobs that can be executed asynchronously in the background. When you run QUEUE=* bundle exec rake resque:work, a worker process runs constantly and polls the queue. Once a job is enqueued, an available worker pops it from the queue and starts working on it. This architecture is quite scalable, as you can have multiple workers listening to the queues if you'd like.
To define a job, you do this:
class MyWeeklyEmailSenderJob
def self.perform
# Your code to send weekly emails
end
end
While you can enqueue this job to the queue yourself from anywhere (e.g. from a controller as a response to an action), in your case you want it to automatically be placed into the queue once a week. This is what Resque-scheduler is for. It allows you to configure a file such as app/config/resque_schedule.yml in which you can define which jobs should be enqueued in which time interval. For example:
send_weekly_emails:
cron: 0 8 * * Mon
class: MyWeeklyEmailSenderJob
queue: email_sender_queue
description: "Send weekly emails"
Remember that a scheduling process has to run in order for this to work with bundle exec rake resque:scheduler.
thanks guys , actually i tried rufus scheduler gem and it worked for me , i guess it's the best and easier solution
It's nice to see Rails 4.2 come with Active Job as a common interface for background jobs. But I can't find how to start a worker in the document. It seems that the document is still immature (e.g. the right version of Sneakers is only referred to in Rails' Gemfile), so I'm not sure if the "running workers" part is not in Active Job or just not mentioned in docs.
So with Active Job, do I still need to manually start the job watcher threads like sidekiq or in my case, rake sneakers:run? If so, where should I put these commands to let rails server run these parallel tasks automatically in a develop environment?
ActiveJob is just a common interface. You still need the backend gem, and you still need to launch it separately from your server (it is a separated process, which is the objective).
Sample using resque:
In the Gemfile:
gem 'resque'
In the terminal, launching a worker:
bin/resque work
The case is similary when using sidekick, delayed job or something else.
If you want to launch the server & worker in a single command, you can create a short bash script for it, but I would advise not doing so: having two separated console helps to watch what is happening on each side (web app & worker).
A better solution would be to use the foreman gem to manage starting & stopping your process.
You can create a simple Procfile with the processes to start:
web: bundle exec rails s
job: bundle exec resque work
And then just start both using foreman:
foreman start
By default, foreman will interleave the logs of the process in the console, but this can be configured.
You still have to run the job thread watcher.
I need some code executed once per day. Can be more than once a day and missing a day isn't the end of the world. That code will make sure users get some bonus points based on certain criteria. I'll keep track if they've already received the bonus points so it doesn't double up..
Some simple cron job calling a particular controller once in a while is perfect:
curl http://localhost/tasks/pulse
Of course a real crontab entry works great. Or is there an internal mechanism for this kind of thing in Rails? I'm using the latest stable Rails (currently 3.2.9).
The only wrinkle is this needs to work in Heroku too.
I just noticed Heroku's Scheduler. Looks great for Heroku. I can just run those tasks in my dev/test environment manually. Is this the best way to handle pulses/cron jobs in Rails? With rake tasks? Easy to incorporate running rake tasks in tests?
The Heroku Scheduler works great and is easy to set up!
You could check out this gem called whenever its a Ruby gem that provides a clear syntax for writing and deploying cron jobs. It's well maintained, not used it on Heroku myself but worth a look.
You can do loads of stuff like
every 3.hours do
runner "MyModel.some_process"
rake "my:rake:task"
command "/usr/bin/my_great_command"
end
I'm new to Ruby on Rails, and I wanted to perform some periodical tasks but I found out that I didn't know how to set up any cron task in RoR. Is there any basic tutorial how to set up cron in RoR? Currently I'm running RoR on Webbrick with Mysql DB on Windows platform.
There are few ways to solve your problem.
If you want to use Cron, the best way of using it with Rails is to use a gem whenever. To find out more about whenever, and a quick tutorial on how to use it, check this Railscast Episode 164. Cron best suits when you have actions that need to be run every constant time interval (eg. emptying your users' trashes)
You can also use DelayedJob which best suits when you have some actions that last long time and you don't want your user wait until their actions finish (eg. when you deliver a lot of emails) or when you want to take some actions in X hours. More about DelayedJob you will find here: https://github.com/collectiveidea/delayed_job
You can also Resque with Redis: https://github.com/blog/542-introducing-resque
Check out http://rubygems.org/gems/delayed_job
You can create a daemon script, which always be in memory.
For example, https://github.com/DAddYE/foreverb
For minimal setup of "cron-like" tasks in "core" rails/ruby, I created https://github.com/Ebbe/arask
No need to install anything (other than the gem) or setup anything outside of rails.
Add gem 'arask' to your Gemfile, run bundle install, rails generate arask:install and rails db:migrate.
Now you can setup your tasks in the file config/initializers/arask.rb:
arask.create task: 'send:logs', cron: '0 2 * * *' # At 02:00 every day
arask.create script: 'puts "IM ALIVE!"', interval: :daily
arask.create task: 'my:awesome_task', interval: :hourly
arask.create task: 'my:other_awesome_task', interval: 2.hours
The tasks will automatically run if the server is running.