Akeeba Amazon S3 Connector

A lightweight Amazon S3 connector implementation for PHP 5.3 or later

After having a lot of impossible to debug problems with Amazon's Guzzle-based AWS SDK we decided to roll our own connector for Amazon S3. This is by no means a complete implementation, just a small subset of S3's features which are required by our software. The design goals are simplicity and low memory footprint.

This code is loosely based on S3.php written by Donovan Schonknecht and available at http://undesigned.org.za/2007/10/22/amazon-s3-php-class under a BSD-like license. This repository no longer reflects the original author's work and should not be confused with it.

This software is distributed under the GNU General Public License version 3 or, at your option, any later version published by the Free Software Foundation (FSF). In short, it's "GPLv3+".

Using the connector

Get a connector object

$configuration = new Configuration(
	'YourAmazonAccessKey',
	'YourAmazonSecretKey'
);

$connector = new Connector($configuration);

If you are running inside an Amazon EC2 instance you can fetch temporary credentials from the instance's metadata server using the IAM Role attached to the EC2 instance. In this case you need to do this (169.254.169.254 is a fixed IP hosting the instance's metadata cache service):

$role = file_get_contents('http://169.254.169.254/latest/meta-data/iam/security-credentials/');
$jsonCredentials = file_get_contents('http://169.254.169.254/latest/meta-data/iam/security-credentials/' . $role);
$credentials = json_decode($jsonCredentials, true);
$configuration = new Configuration(
	$credentials['AccessKeyId'],
	$credentials['SecretAccessKey'],
	'v4',
	$yourRegion
);
$configuration->setToken($credentials['Token']);

$connector = new Connector($configuration);

where $yourRegion is the AWS region of your bucket, e.g. us-east-1. Please note that we are passing the security token ($credentials['Token']) to the Configuration object. This is REQUIRED. The temporary credentials returned by the metadata service won't work without it.

Also worth noting is that the temporary credentials don't last forever. Check the $credentials['Expiration'] to see when they are about to expire. Amazon recommends that you retry fetching new credentials from the metadata service 10 minutes before your cached credentials are set to expire. The metadata service is guaranteed to provision fresh temporary credentials by that time.

Listing buckets

$listing = $connector->listBuckets(true);

Returns an array like this:

array(2) {
  'owner' =>
  array(2) {
    'id' =>
    string(64) "0123456789abcdef0123456789abcdef0123456789abcdef0123456789abcdef"
    'name' =>
    string(8) "someUserName"
  }
  'buckets' =>
  array(3) {
    [0] =>
    array(2) {
      'name' =>
      string(10) "mybucket"
      'time' =>
      int(1267730711)
    }
    [1] =>
    array(2) {
      'name' =>
      string(10) "anotherbucket"
      'time' =>
      int(1269516249)
    }
    [2] =>
    array(2) {
      'name' =>
      string(11) "differentbucket"
      'time' =>
      int(1354458048)
    }
  }
}

Listing bucket contents

$listing = $connector->getBucket('mybucket', 'path/to/list/');

If you want to list "subdirectories" you need to do

$listing = $connector->getBucket('mybucket', 'path/to/list/', null, null, '/', true);

The last parameter (common prefixes) controls the listing of "subdirectories"

Uploading (small) files

From a file:

$input = Input::createFromFile($sourceFile);   
$connector->putObject($input, 'mybucket', 'path/to/myfile.txt');

From a string:

$input = Input::createFromData($sourceString);   
$connector->putObject($input, 'mybucket', 'path/to/myfile.txt');

From a stream resource:

$input = Input::createFromResource($streamHandle, false);   
$connector->putObject($input, 'mybucket', 'path/to/myfile.txt');

In all cases the entirety of the file has to be loaded in memory.

Uploading large file with multipart (chunked) uploads

Files are uploaded in 5Mb chunks.

$input = Input::createFromFile($sourceFile);
$uploadId = $connector->startMultipart($input, 'mybucket', 'mypath/movie.mov');

$eTags = array();
$eTag = null;
$partNumber = 0;

do
{
	// IMPORTANT: You MUST create the input afresh before each uploadMultipart call
	$input = Input::createFromFile($sourceFile);
	$input->setUploadID($uploadId);
	$input->setPartNumber(++$partNumber);
	
	$eTag = $connector->uploadMultipart($input, 'mybucket', 'mypath/movie.mov');

	if (!is_null($eTag))
	{
		$eTags[] = $eTag;
	}
}
while (!is_null($eTag));

// IMPORTANT: You MUST create the input afresh before finalising the multipart upload
$input = Input::createFromFile($sourceFile);
$input->setUploadID($uploadId);
$input->setEtags($eTags);

$connector->finalizeMultipart($input, 'mybucket', 'mypath/movie.mov');

As long as you keep track of the UploadId, PartNumber and ETags you can have each uploadMultipart call in a separate page load to prevent timeouts.

Get presigned URLs

Allows browsers to download files directly without exposing your credentials and without going through your server:

$preSignedURL = $connector->getAuthenticatedURL('mybucket', 'path/to/file.jpg', 60);

The last parameter controls how many seconds into the future this URL will be valid.

Download

To a file with absolute path $targetFile

$connector->getObject('mybucket', 'path/to/file.jpg', $targetFile);

To a string

$content = $connector->getObject('mybucket', 'path/to/file.jpg', false);

Delete an object

$connector->deleteObject('mybucket', 'path/to/file.jpg');

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