Best approach to create a background task - ruby-on-rails

Question

I'm currently developing a Ruby on Rails application that on certain moment has to import a (at least for me) medium-large dataset using a third-party API. It has to do an average of 6000 API calls. One after another. It lasts about 20 minutes.
Right now I have made a rails task that does everything as I want (calls, write to db, etc). But now I want this task/code to be ALSO called from a button on the web. I know it's not a good approach to let the controller call the task so that's why I'm asking.
I want this import code to be available to be called from a controller and a task, because later I want to be able to call this task from a cronjob, and even if it's possible to have callbacks on the progress of the task on the controller, i.e. know how many calls are left.

Answer 1

I know it's not a good approach to let the controller call the task
There's nothing wrong with having a button trigger a background task like this, but of course you need to do so with care. For example, perhaps:
If the task is already running, don't let a second instance overlap.
If the task runs for too long, automatically kill it.
Carefully restrict who can trigger this.
There are many libraries available for implementing a progress bar, or you could even write a custom implementation. For example, see this blog post - which works by polling the current progress:
// app/views/exports/export_users.js.haml
:plain
var interval;
$('.export .well').show();
interval = setInterval(function(){
$.ajax({
url: '/progress-job/' + #{#job.id},
success: function(job){
var stage, progress;
// If there are errors
if (job.last_error != null) {
$('.progress-status').addClass('text-danger').text(job.progress_stage);
$('.progress-bar').addClass('progress-bar-danger');
$('.progress').removeClass('active');
clearInterval(interval);
}
progress = job.progress_current / job.progress_max * 100;
// In job stage
if (progress.toString() !== 'NaN'){
$('.progress-status').text(job.progress_current + '/' + job.progress_max);
$('.progress-bar').css('width', progress + '%').text(progress + '%');
}
},
error: function(){
// Job is no loger in database which means it finished successfuly
$('.progress').removeClass('active');
$('.progress-bar').css('width', '100%').text('100%');
$('.progress-status').text('Successfully exported!');
$('.export-link').show();
clearInterval(interval);
}
})
},100);
An variant approach you could consider is to use a websocket to see progress, rather than polling.

Answer 2

Convert the specific tasks into background jobs, i.e. (active job, sideqik), so your system can continue working while it's doing the tasks. Create classes for each task and call those classes within your background jobs or cronjobs.
One design pattern that could fit here is the "command" pattern, I gave you a list of things you can Google :).

Answer 3

Just move most of the code from the task to a module or method in a model. You can call this code from the task (as your do it now) or from a background job that would start through a controller when you press a button on a view.