S3 file processing

S3 can trigger Lambda functions (opens in a new tab) whenever a file is added, modified, or deleted in an S3 bucket.

This can be used to process files, for example to resize images, generate thumbnails, convert videos, after they are uploaded to S3.

To handle S3 events, extend the S3Handler class:

use Bref\Context\Context;
use Bref\Event\S3\S3Event;
use Bref\Event\S3\S3Handler;
 
class MyHandler extends S3Handler
{
    public function handleS3(S3Event $event, Context $context): void
    {
        $bucketName = $event->getRecords()[0]->getBucket()->getName();
        $fileName = $event->getRecords()[0]->getObject()->getKey();
 
        // do something with the file
    }
}

Then, create a Lambda function that listens to S3 events with the handler you created:

serverless.yml

functions:
    # ...
    resizeImage:
        handler: App\MyHandler
        runtime: php-82
        events:
            - s3: photos

The App\MyHandler class will be instantiated by Laravel's service container.

The S3 bucket will automatically be created on deployment. You can listen to an existing S3 bucket via the existing: true option (opens in a new tab). Or you can use the Storage feature of the Lift plugin (opens in a new tab). For example:

serverless.yml

constructs:
    reports-bucket:
        type: storage
 
functions:
    resizeImage:
        handler: handler.php
        runtime: php-82
        events:
            - s3:
                bucket: ${construct:reports-bucket.bucketName}
                existing: true
                event: s3:ObjectCreated:*
# ...

Learn more about all the options available for S3 in serverless.yml in the Serverless Framework documentation (opens in a new tab).

⚠️

Watch out for recursive triggers: if your Lambda function writes files to the same S3 bucket, it will trigger itself again. You can avoid this by using a different bucket for the output files, or by using a prefix for the output files.

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