automatically invalidate URL's in cloudfront when a file is updated in S3

index.py

import boto3
from botocore.vendored import requests

client = boto3.client('cloudfront')

def handler(event, context):
    for record in event['Records']:
        key = record['s3']['object']['key']
        items = [key]
        
        if key.endswith('index.html'):
            items.append(key[:-10])
                    
        response = client.create_invalidation(
            DistributionId='E2KMYV1XU86AEJ',
            InvalidationBatch={
                'Paths': {
                    'Quantity': len(items),
                    'Items': ['/'+item for item in items]
                },
                'CallerReference': record['eventTime'] + '/' + key
            }
    )

(attached to the ObjectCreated event on an S3 bucket)