Schedule job in rails

rubyonrails-talk
1

Dear all

I created a module in my_rails_project/lib/ssc.rb. I can execute the method in rails console (i.e. SSC::Monitor.method1(a,b)). How can I execute the method regularly? I am using Linux, can I do it using `crontab`? Thank you.

module SSC   class Monitor     def self.method1(a,b)        bla bla bla        some code will access the model class     end

    def self.method1(a,b)     end   end end

Many thanks

Valentino

2

Dear all

I tried script/runner for this, but every execution need to initialize the rails environment. Any other good idea for it? What is your good/best practice?

Many thanks

Valentino

3

Especially if this method is accessing your models, I don't see a way around loading your entire rails environment.

I think a more common solution would be to create a rake task which you invoke with cron...

4

I think a more common solution would be to create a rake task which you invoke with cron...

Thank for your reply

How can I do it with rake task? Can you give me some reference?

Thanks again

Valentino

5

Check out #128 Starling and Workling - RailsCasts and #130 Monitoring with God - RailsCasts

There are a number of different ways to have a task persist, and run on a regular schedule. I've also previously used background-db and cron seems to be a popular option. I tend to go with whatever has the easiest tutorials that i can find!

Anyone else feel free to weigh in if you have any more suggestions.

6

I use cron to schedule wget:

wget http://localhost:3000/cron

cron_controller invokes your method

7

That’s a great idea, until someone in the outside finds out about that path/resource. You’re opening up too much and scriptkiddies can get happy attempting a DoS. Wondering if you handle that somehow (IP address check or something)?

8

Harold A. Gimenez wrote:

That's a great idea, until someone in the outside finds out about that path/resource. You're opening up too much and scriptkiddies can get happy attempting a DoS. Wondering if you handle that somehow (IP address check or something)?

How about using HTTP basic authentication so only authorized clients can access the controller action? Which would be only your rake task.

I haven't thought this through, It's just the first thing that came to mind.

9

If there are no hostile users on the server, in the controller:

if local_request?   do the action else   ignore or log hostile action end

HTH,   Jeffrey

Quoting Harold A. Gimenez <harold.gimenez@gmail.com>:

10

That can be spoofed

Blog: http://random8.zenunit.com/ Learn rails: http://sensei.zenunit.com/

11

wget http://localhost:3000/cron

cron_controller invokes your method

Thanks, it is a very good idea. How about if my action require 2 parameters? How to do that?

Let me further elabroate on my question. For example in my Cron Controller

def someaction    some_method(params[:one],params[:two]) end

Is it possible to do this in my crontab as follow?

10 10 * * * wget http://localhost:3000/cron/someaction "para1" "para2"

Many thanks

Valentino

12

I'm not sure, but an alternative is to put the wget command in a small shell script (Linux talk, iiuc) or a .bat file (MS talk, iiuc). Then invoke that shell script or .bat file from cron.

Randy Kramer

13

No quite like that. If you’re sending an HTTP GET request to any URL, you would pass parameters to the URL itself, something like: http://localhost:3000/cron?param1=value1&param2=value2 etc

What looks attractive to me about this approach (of using wget via cron instead of a rake task) is that you are not bringing up an entire rails environment to handle a task. There’s less overhead. Just be sure to lock it down with a combination of things that have been suggested here: IP Address check, local_request?, http basic authentication. There may be more you can do…

14

Citation needed.

Quoting Julian Leviston <julian@coretech.net.au>:

15

def someaction    some_method(params[:one],params[:two]) end

Is it possible to do this in my crontab as follow?

10 10 * * * wgethttp://localhost:3000/cron/someaction"para1" "para2"

You will need to pass the para1, and para2 to the someaction method so at a minimum you have to change the signature of the someaction method as below:

def someaction para1, para2   ... end

now within this method you can do anything you want only thing is that this method needs to be public in scope and you need to make sure that it requires no authentication otherwise your wget request will fail. I usually use script/runner in Rails for such needs. wget may or may not work depending on how restful your routes are and controller action is.

Bharat