Amazon S3 Transfer Manager

The PHP SDK Amazon S3 transfer manager is used to upload entire directories to an Amazon S3 bucket and download entire buckets to a local directory.

Uploading a local directory to S3

The Aws\S3\Transfer object is used to perform transfers. The following example shows how to recursively upload a local directory of files to an Amazon S3 bucket.

// Create an S3 client
$client = new \Aws\S3\S3Client([
    'region'  => 'us-west-2',
    'version' => '2006-03-01',

// Where the files will be source from
$source = '/path/to/source/files';

// Where the files will be transferred to
$dest = 's3://bucket';

// Create a transfer object.
$manager = new \Aws\S3\Transfer($client, $source, $dest);

// Perform the transfer synchronously.

In this example, we created an Amazon S3 client, created a Transfer object, and performed transfer synchronously. Using the above example demonstrates the bare minimum amount of code needed to perform a transfer. The transfer object can perform transfers asynchronously and has various configuration options that can be used to customize the transfers.

You can upload the local files to a "sub-folder" of a an Amazon S3 bucket by providing a key prefix in the s3:// URI. The following example uploads the local files on disk to the bucket bucket and stores the files under the foo key prefix.

$source = '/path/to/source/files';
$dest = 's3://bucket/foo';
$manager = new \Aws\S3\Transfer($client, $source, $dest);

Downloading an Amazon S3 bucket

You can recursively download an Amazon S3 bucket to a local directory on disk by specifying the $source argument as an Amazon S3 URI (e.g., s3://bucket) and the $dest argument as the path to a local directory.

// Where the files will be source from
$source = 's3://bucket';

// Where the files will be transferred to
$dest = '/path/to/destination/dir';

$manager = new \Aws\S3\Transfer($client, $source, $dest);


The SDK will automatically create any necessary directories when downloading the objects in the bucket.

You can include a key prefix in the Amazon S3 URI after the bucket to download only objects stored under a "pseudo-folder". The following example downloads only files stored under the "/foo" key prefix of the given bucket.

$source = 's3://bucket/foo';
$dest = '/path/to/destination/dir';
$manager = new \Aws\S3\Transfer($client, $source, $dest);


The Transfer object constructor accepts the following arguments:

The Aws\ClientInterface object to use for performing the transfers.

(string|``Iterator``) The source data being transferred. This can point to a local path on disk (e.g., /path/to/files) or an Amazon S3 bucket (e.g., s3://bucket). The s3:// URI may also contain a key prefix that can be used to only transfer objects under a common prefix.

If the $source argument is an Amazon S3 URI, then the $dest argument must be a local directory (and vice versa).

In addition to providing a string value, you can also provide an \Iterator object that yields absolute filenames. If you provide an iterator, then you must provide a base_dir option in the $options associative array.

The destination where the files will be transferred. If the $source argument is a local path on disk, then $dest must be an Amazon S3 bucket URI (e.g., s3://bucket). If the $source argument is an Amazon S3 bucket URI, then the $dest argument must be a local path on disk.
An associative array of transfer options.

Transfer Options

(string) Base directory of the source, if $source is an iterator. If the $source option is not an array, then this option is ignored.
(callable) A callback to invoke before each transfer. The callback should have a function signature like function (Aws\Command $command) {...}. The provided command will be either a GetObject, PutObject, CreateMultipartUpload, UploadPart, or CompleteMultipartUpload command.
(int) Size in bytes in which a multipart upload should be used instead of PutObject. Defaults to 16777216 (16 MB).
(int, default=5) Number of files to upload concurrently. The ideal concurrency value will vary based on the number of files being uploaded and the average size of each file. Generally speaking, smaller files benefit from a higher concurrency while larger files will not.
(bool) Set to true to print out debug information for transfers. Set to an fopen() resource to write to a specific stream rather than writing to STDOUT.

Async transfers

The Transfer object is an instance of GuzzleHttp\Promise\PromisorInterface, which means that the transfer can occur asynchronously and is initiated by calling the promise method of the object.

$source = '/path/to/source/files';
$dest = 's3://bucket';
$manager = new \Aws\S3\Transfer($client, $source, $dest);

// Initiate the transfer and get a promise.
$promise = $manager->promise();

// Do something when the transfer is complete using the then() method.
$promise->then(function () {
    echo 'Done!';

The promise will be rejected if any of the files fail to transfer. You can handle the failed transfer asynchronously using the otherwise method of the promise. The otherwise function accepts a callback to invoke when an error occurs. The callback accepts the $reason for the rejection, which will typically be an instance of Aws\Exception\AwsException (though a value of any type may be delivered to the callback).

$promise->otherwise(function ($reason) {
    echo 'Transfer failed: ';

Because the Transfer object returns a promise, these transfers can occur concurrently with other asynchronous promises.

Customizing the Transfer Manager's commands

Custom options can be set on the operations executed by the transfer manager via a callback passed to its constructor.

$uploader = new Transfer($s3Client, $source, $dest, [
    'before' => function (\Aws\Command $command) {
        // Commands can vary for multipart uploads, so check which command
        // is being processed
        if (in_array($command->getName(), ['PutObject', 'CreateMultipartUpload'])) {
            // Set custom cache-control metadata
            $command['CacheControl'] = 'max-age=3600';
            // Apply a canned ACL
            $command['ACL'] = strpos($command['Key'], 'CONFIDENTIAL') === false
                ? 'public-read'
                : 'private';