Python script through php on Amazon EC2

Question

I am trying to run a simple python script through php on Amazon EC2 instance.

The file is working fine on terminal i.e am getting the output. But when am trying the same in browser, am getting a blank page.

I tried few things, such as adding www-data ALL=(ALL) ALL in sudoers file in etc folder. etc/sudoers.

I also tried disabling SELINIX.

I checked with the php's safe mode and few other things which I found over here(SO).

I have followed this AWS TUTORIAL. I did everything exactly what's written in there. I believe there is some permission issue.

Can anyone please check it out. Am stuck with this for 2 days..

EDIT Python script

#!/usr/bin/env python
# -*- coding: UTF-8 -*-
# enable debugging
import cgitb
print "Hello world"
cgitb.enable()

Php file:

<?php header("Content-Type:text/plain");
$output = escapeshellcmd('/home/ec2-user/anaconda/envs/xyz/bin/python2.7 /var/www/html/xyz/a.py');
$a=shell_exec($output);
echo ($a);
//echo file_get_contents("/var/www/html/xyz/a.py");
?>

• Maximilian Peters: without the script or access to your server it is impossible to guess what's going wrong. When you print a simple HelloWorld HTML page in your script, does it work?
• driftking9987: Added the scripts. Maybe that can help. When am executing in terminal with php try.php it's printing "Hello world". But in browser, it's empty.
• Maximilian Peters: did you check the log files and which user owns the python scripts?
• e4c5: Why on earth do you want to run a python (or any other script) from a web page? That's suicidal. Better to use a task queue. And anyway are you quite sure this is something that the php page can't do on it's own?
• driftking9987: @Ashafix, root is the owner of the python script. #e4c5, i need to execute a python script for my android app. I only found this way which worked for me.

Answer 1

After a lot of "scratching my head", I finally figured it out.

First of all you one need to figure out the current user who is executing the php. One can either check out php.info file or use

$processUser = posix_getpwuid(posix_geteuid());
print $processUser['name'];

This will give you the user who is executing the code. In my case it was apache rather than www-data (I shouldn't have assumed so in first place).

After that you will need to edit the sudoers file (etc/sudoers)

Add the lines over there.

apache ALL=NOPASSWD:/var/www/myfile.py
apache ALL=NOPASSWD:/usr/bin/pythondestination

or you can simply add

apache ALL=(ALL) NOPASSWD:ALL

(You probably should just specify the path).

Then execute the script through php.

• Volatil3: For some reason it is not working, escapeshellcmd is not executing/outputting at all.
• sivi: This is the wrong answer don't do it if you like the next two hours. stackoverflow.com/a/56110051/1984636

Answer 2

I guess first place one should look is the apache error log at. You don't want to enable sudo. Please consider checking the error log of apache to understand what is the underlying problem at:

/var/log/apache or similar directory

Please review these posts for a better solution and review of the problem:

How to execute shell_exec on EC2 Linux

https://forums.aws.amazon.com/thread.jspa?messageID=692394

php shell_exec() command is not working