Pass additional information to Lambda triggered by S3EventNotification

Question

I have an architecture were a client uploads an image to an S3 bucket and this upload triggers a Lambda function through an S3 event notification.

This Lambda does some pre-processing on this image and then saves it on another bucket under the **client's folder**. However, this Lambda function does not know who the user is and thus cannot save the image in the user's folder .

If the Event Notification was able to pass some extra information, like user ID, to the Lambda this could be done.

Is there a way to do this or an alternative solution?

Answer

When the client uploads the image to S3 add a metadata to it which contains some user information. A sample of how to add a metadata is demonstrated in the link below
https://docs.aws.amazon.com/sdk-for-ruby/v3/developer-guide/s3-example-upload-bucket-item-with-metadata.html

Now in your Lambda you can read the metadata object using s3.head_object(Bucket=bucket, Key=key)

Pass additional information to Lambda triggered by S3EventNotification

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