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).
Related
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
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
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 created an app that uses the whenever gem. The gem creates cron jobs. I got it working locally but can't seem to get it working on heroku cedar. What's the command to do this?
running:
heroku run whenever --update-crontab job1
doesn't work
Short answer: use the scheduler add-on: http://addons.heroku.com/scheduler
Long answer: When you do heroku run, we
spin up a dyno
put your code on it
execute your command, wait for it to finish
throw the dyno away
Any changes you made to crontab would be immediately thrown away. Everything is ephemeral, you cannot edit files on heroku, just push new code.
You need to add Heroku Scheduler addon.
You can add it directly from your dashboard or using following commands:
install the add-on:
heroku addons:create scheduler:standard
Create a rake task in lib/tasks
# lib/tasks/scheduler.rake
task :send_reminders => :environment do
User.send_reminders
end
Schedule job
Visit Heroku Dashboard
Open your app
Select Scheduler from add-ons list
Click Add Job, enter a task and select frequency.
e.g. Add rake send_reminders, select "Daily" and "00:00" to send reminders every day at midnight.
The other answers specify you should use the Heroku Scheduler add-on, and it is able to run a background tasks indeed, but it doesn't support the flexibility of cron.
There's another add-on, called Cron To Go, that is able to run your jobs on one-off dynos with cron's flexibility. You can also specify a timezone for your job and get notifications (email or webhook) when job fail, succeed or start.
(Full disclosure - I work for the company that created and operates Cron To Go)
If you want to:
Use Heroku Scheduler
Run tasks every minute (not 10 min)
Don't care about dyno hours
This was my solution hack to run jobs every minute - assuming the task completes in under 60 seconds.
task start_my_service: :environment do
1.upto(9) do |iteration|
start_time = DateTime.now
Services::MyService.call
end_time = DateTime.now
wait_time = 60 - ((end_time - start_time) * 24 * 60 * 60).to_i
sleep wait_time if wait_time > 0
end
end
Heroku doesn't support cron jobs. And there are two drawbacks to the Heroku Scheduler :
you cannot choose an arbitrary interval or time at which to run jobs (it's either every 10 mins, 1 hour or daily).
your jobs are not defined in code, hence not in your versioning system and not easy to keep track of or modify.
Heroku does provide an alternative : custom clock processes. But the clock process requires its own dyno, and "Since dynos are restarted at least once a day some logic will need to exist on startup of the clock process to ensure that a job interval wasn’t skipped during the dyno restart".
Simple scheduler is a gem made specifically made for scheduling on Heroku, but seems a bit hackish.
I ended up using sidekiq-cron. Only drawback : if sidekiq is down right when a job is scheduled to run, the job won't run.
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.