crontab didn't work in Rails rake task

Question

I have a rake task in my Rails application,and when I execute the order in my rails app path /home/hxh/Share/ruby/sport/:

rake get_sportdata

This will work fine.

Now,I want to use crontab to make this rake to be a timed task .so,I add a task:

* * * * * cd /home/hxh/Share/ruby/sport && /usr/local/bin/rake get_sportdata >/dev/null 2>&1

But this doesn't work.I get the log in cron.log file:

Job `cron.daily' terminated

I want to know where the error is.

Answer 1

Does the "cd /home/hxh/Share/ruby/sport && /usr/local/bin/rake get_sportdata >/dev/null 2>&1" can work in your terminal?

But use crontab in Rails normally is not a good idea. It will load Rails environment every time and slow down your performance.

I think whenever or rufus-scheduler are all good. For example, use rufus-scheduler is very easy. In config\initializers\schedule_task.rb

require 'rubygems'
require 'rufus/scheduler'


scheduler = Rufus::Scheduler.start_new(:thread_name => "Check Resources Health")
scheduler.every '1d', :first_at => Time.now do |job|
  puts "###########RM Schedule Job - Check Resources Health: #{job.job_id}##########"
  begin
    HealthChecker.perform
  rescue Exception => e
    puts e.message
    puts e.backtrace
    raise "Error in RM Scheduler - Check Resources Health " + e.message
  end
end

And implement "perform" or some other class method in your controller, now the controller is "HealthChecker". Very easy and no extra effort. Hope it help.

Answer 2

So that you can test better, and get a handle on whether it works I suggest:

1. Write a shell script in [app root]/script which sets up the right environment variables to point to Ruby (if necessary) and has the call to rake. E.g., something like script/get-sportdata.sh.
2. Test the script as root. E.g., first do sudo -s.
3. Call this script from cron. E.g., * cd [...] && script/get-sportdata.sh. If necessary, test that line as root too.

That's been my recipe for success, running rake tasks from cron on Ubuntu. This is because the cron environment is a bit different than the usual shell setup. And so limiting your actual cron jobs to simple commands to run a particular script are a good way to divide the configuration into smaller parts which can be individually tested.