To set right ownership to opencart directory

I have an installed LAMP in AWS t2.micro
Output of Linux ip-172-31-1-221 4.9.27-14.31.amzn1.x86_64 #1 SMP Wed May 10 01:58:40 UTC 2017 x86_64 x86_64 x86_64 GNU/Linux

Downloaded opencart 2.3.0.2 and uncompressed to /var/www/html/opencart
Output of drwxrwsr-x 7 ec2-user www 4096 Jun 2 16:31 opencart

While trying to install Opencart, I am getting this issue
/var/www/html/opencart/config.php Unwritable
/var/www/html/opencart/admin/config.php Unwritable

/var/www/html/opencart/image/ Unwritable
/var/www/html/opencart/image/cache/ Unwritable
/var/www/html/opencart/image/catalog/ Unwritable
/var/www/html/opencart/system/storage/cache/ Unwritable
/var/www/html/opencart/system/storage/logs/ Unwritable
/var/www/html/opencart/system/storage/download/ Unwritable
/var/www/html/opencart/system/storage/upload/ Unwritable
/var/www/html/opencart/system/storage/modification/ Unwritable

Doing some R&D via google, I found that need to set chown –R apache: /var/www/html/opencart.

I did so and changed the owner of opencart folder and got all folders writable and installation was complete.
However while using ftp, using ec2-user, don’t have write permission.
Also I want to keep my opencart installation secure, so won’t be able to set 0777 permission to Opencart Root folder.

Please suggest me what should be the owner, and also my ftpuser "ec2-user" should have all access permission.

A possible easy solution for this
Ernie
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OpenCart Repair and Cache Clear
A simple php file that will set files permissions to 0644 and folders permissions to 0755.
And it will delete the cache of the OpenCart OCmod and the VQmod. It will work with most
of the 2.X versions, you can try... no risk at all.
https://www.opencart.com/index.php?rout ... n_id=26276
---
Locaweb Cache Permission Fix
Set permissions for OCMod and cache files
https://www.opencart.com/index.php?rout ... n_id=21373

@IP_CAM , I need suggestion for setting permission to opencart folders.
This is the output of total 16
-rw-rw-r-- 1 ec2-user www 132 May 25 18:42 index.html
drwxrwsr-x 7 ec2-user www 4096 Jun 2 16:31 opencart
drwxrwsr-x 7 ec2-user ec2-user 4096 Jun 2 16:19 opencart_backup
-rw-rw-r-- 1 ec2-user www 20 May 25 19:34 phpinfo.php

I want the to set permission in such a way that the ec2-user ftpuser also can upload files via ftp client.