Move file with Rake permission denied - ruby-on-rails

Question

I have a Rake at the end of which the server moves the processed file from a folder to another one, using FileUtils.mv, like this:
FileUtils.mv('/path-to-upload-folder/'+filename, '/path-to-imported-folder/'+filename) if File.exist?('/path-to-upload-folder/'+filename)
If i run this command from within the rails server (I have an action that is a copy of the rake task, just for simplicity of debugging inside a controller), everything goes fine (probably because I run the server with root privileges with rvmsudo).
When running from the Rake task, I get a permission denied error, like this
Errno::EACCES: Permission denied # sys_fail2 -
The source folder is called uploads, and the destination folder is the imported folder. Following the permissions and the user and groups of the folder
drwxr-xr-x 2 malatini malatini 4096 lug 14 14:26 imported/
drwxr-xr-x 2 www-data www-data 135168 lug 14 14:26 uploads/
where malatini is my current user.
I know that for running a raw mv from the two folders I need to be a sudo user, but why can I run the same command from within the Rails servers without any problem?
I also tried to change permissions and owners/groups of the destination folder, but with no luck.
Reading here I suppose the problem is the user that is running the rake task. The same problem happens either if I manually run the rake task, either if it is run as a cron job.
I am running under
Debian 3.16.7-ckt11-1 (2015-05-24) x86_64 GNU/Linux
Any suggestion?
EDIT:
As #Nic Nilov suggested I tried to change owner and group of source and destination foleders, and actually I managed to perform the mv, and hence rake task, changing owner and group of both folders to malatini
drwxr-xr-x 2 malatini malatini 4096 lug 14 14:26 imported/
drwxr-xr-x 2 malatini malatini 135168 lug 14 14:26 uploads/
but in this way, apache (which is in charge of moving files to uploads folder) is not able to write to uploads folder. No other configuration is working (not just the group of uploads folder, nor the 777 to imported folder).

Answer 1

You basically answered your own question. This is a permission issue, related to the OS user under which the move operation is attempted. It works from Rails since, as you say, you run it with rvmsudo.
Two ways around that would be to either run your rake task from a privileged user or set ownership on both folders such that the current user you run rake under is allowed to perform mv.
On your folders both user and group set to be the same. You could set their group to the group of the user running rake, e.g.:
chgrp malatini ./uploads
This would make malatini group the owner of both folders:
drwxr-xr-x 2 malatini malatini 4096 lug 14 14:26 imported/
drwxr-xr-x 2 www-data malatini 135168 lug 14 14:26 uploads/
Which should allow the mv operation.
UPDATE
When running rake under a privileged user and doing that from cron and to avoid keeping the password stored anywhere you can use NOPASSWD directive.
See for more details this askubuntu answer.