How to Properly Deploy Web Apps via SFTP with Git

Uploading files is an integral aspect of any deployment process, and the underlying implementation can vary depending on the type of your server.

You can easily upload your files to an SFTP server using an open source desktop client like Filezilla. Those who have used this are aware that this process is cumbersome and irritating as it doesn't let us automate our deployment process, and we always need to upload the whole project, even if we have modified only a part of the files of our codebase.

The PHPSECLIB (PHP Secure Communications Library) package has an awesome API for routine SFTP tasks: it uses some optional PHP extensions if they're available, and falls back on an internal PHP implementation otherwise. You don't need any additional PHP extension to use this package, the default extensions that are packaged with PHP will do. In this article, we will first cover various features of PHPSECLIB - SFTP, including but not limited to uploading or deleting files. Then, we will take a look at how we can use Git in combination with this library to automate our SFTP deployment process.

Installation

composer require phpseclib/phpseclib

This will install the most recent stable version of the library via Composer.

Authentication

By default, password authentication is used to connect to your SFTP server. A cryptographic key-pair is more secure because a private key takes the place of a password, which is generally much more difficult to brute-force. Using phpseclib, you can connect to your SFTP server with any of the following authentication methods:

1. RSA key
2. Password Protected RSA key
3. Username and Password (Not recommended)

RSA Key

We will assume that you have a secure RSA key already generated. If you are not familiar with generating a secure RSA key pair, you can go through this article. For a video explanation, you can refer to Creating and Using SSH Keys from Servers For Hackers.

To log in to a remote server using RSA key authentication:

namespace App;

use phpseclib\Crypt\RSA;
use phpseclib\Net\SFTP;

$key = new RSA();
$key->loadKey(file_get_contents('privatekey'));

//Remote server's ip address or hostname
$sftp = new SFTP('192.168.0.1');

if (!$sftp->login('username', $key)) {
    exit('Login Failed');
}

Password Protected RSA Key

If your RSA keys are password protected, do not worry. PHPSECLIB takes care of this particular use case:

namespace App;

use phpseclib\Crypt\RSA;
use phpseclib\Net\SFTP;

$key = new RSA();
$key->setPassword('your-secure-password');
$key->loadKey(file_get_contents('privatekey'));

//Remote server's ip address or hostname
$sftp = new SFTP('192.168.0.1');

if (!$sftp->login('username', $key)) {
    exit('Login Failed');
}

Username and Password

Alternatively, to log in to your remote server using a username and password (we don't recommend this practice):

namespace App;

use phpseclib\Net\SFTP;

//Remote server's ip address or hostname
$sftp = new SFTP('192.168.0.1');

if (!$sftp->login('username', 'password')) {
    exit('Login Failed');
}

For other options such as No Authentication or Multi-Factor authentication please refer to the documentation.

Uploading and Deleting Files

A large part of the deployment process includes uploading files to a server. Uploading files essentially means transferring the contents of a local file to a remote file. The example below creates an index.php file on the server with the contents This is a dummy file:

namespace App;

use phpseclib\Crypt\RSA;
use phpseclib\Net\SFTP;

$key = new RSA();
$key->loadKey(file_get_contents('privatekey'));

//Remote server's ip address or hostname
$sftp = new SFTP('192.168.0.1');

if (!$sftp->login('username', $key)) {
    exit('Login Failed');
}

$sftp->put('index.php', 'This is a dummy file');

Continue reading %How to Properly Deploy Web Apps via SFTP with Git%

by Viraj Khatavkar via SitePoint