lambda_function.py

from __future__ import print_function

import json
import urllib
import boto3

print('Loading function')

s3 = boto3.client('s3')


def lambda_handler(event, context):
    print("Received event: " + json.dumps(event, indent=2))

    # Get the object from the event and show its content type
    bucket = event['Records'][0]['s3']['bucket']['name']
    key = urllib.unquote_plus(event['Records'][0]['s3']['object']['key']).decode('utf8')
    try:
        response = s3.get_object(Bucket=bucket, Key=key)
        print("Last Modified ", response['LastModified'])
        new_key = "to_backup/{}".format(key.split('/')[1])
        old_key = "{}/{}".format(bucket, key)
        print("Copying {} to {}/{}".format(old_key, bucket, new_key))
        resource = boto3.resource('s3')
        resource.Object(bucket, new_key).copy_from(CopySource=old_key)
        return 'OK'
    except Exception as e:
        print(e)
        raise e