s3-copy-lambda-function.py

"""
Copy objects from one bucket/prefix to another bucket with the same prefix.

Used to allow CloudFront logs to get parsed for uploading to ES *AND* analyzed
by WAF.

CloudFront Distribution logs -> s3://es-bucket/incoming -> Lambda (this) -> s3://waf-bucket/

Set environment variable `destination_bucket`

"""
from __future__ import print_function

import json
import os
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'].encode('utf8'))
    destination_bucket = os.environ.get('destination_bucket')
    try:
        response = s3.get_object(Bucket=bucket, Key=key)
        print("CONTENT TYPE: " + response['ContentType'])
        destination_key = key
        destination_key_parts = destination_key.split('/')
        # strip off `/incoming` prefix
        if destination_key_parts[0] == 'incoming':
            destination_key = '/'.join(destination_key_parts[1:])
        print("Copying s3://{}/{} to s3://{}/{} ".format(
            bucket,
            key,
            destination_bucket,
            destination_key))
        response_copy = boto3.resource('s3').Object(
            destination_bucket,destination_key).copy_from(
                CopySource='{}/{}'.format(bucket, key),
                ContentType=response['ContentType'],
                StorageClass='STANDARD'
                )
        return destination_key
        
    except Exception as e:
        print(e)
        print('Error getting object {} from bucket {}. Make sure they exist and your bucket is in the same region as this function.'.format(key, bucket))
        raise e