Snippet to handle s3 events

lambda_s3_event.py

import boto3
import json
import urllib.parse
import uuid
import os

def lambda_handler(event, context):
    
    sfn = boto3.client('stepfunctions')
    
    for record in event.get('Records', []):
        if "ObjectCreated" in record['eventName']:
            bucket = record['s3']['bucket']['name']
            key = urllib.parse.unquote_plus(record['s3']['object']['key'])

            if key[-1] == "/":
                continue

            try:
                sfn.start_execution(
                    stateMachineArn=os.environ['SFN_SM_ARN'],
                    name="lambda-{}".format(str(uuid.uuid4())),
                    input=json.dumps({
                        "mode": "url",
                        "url": "s3://{}/{}".format(bucket, key)
                    })
                )
            except Exception as ex:
                print("Unable to start execution: {}".format(ex))
        else:
            print("Ignore event {}", record['eventName'])

    return {
        'statusCode': 200,
        'body': 'OK'
    }