AWS Lambda function Key Error with trigger on S3

Question

Basic lambda function trying to get contents of the bucket but getting errors though

import json
import urllib.parse
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.parse.unquote_plus(event['Records'][0]['s3']['object']['key'], encoding='utf-8')
    try:
        response = s3.get_object(Bucket=bucket, Key=key)
        print("CONTENT TYPE: " + response['ContentType'])
        return response['ContentType']
    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

Here is the error message when i run the lambda function.

Error message

{
  "errorMessage": "'Records'",
  "errorType": "KeyError",
  "requestId": "5c89bb8e-a70e-4c33-ba00-43174095544e",
  "stackTrace": [
    "  File \"/var/task/lambda_function.py\", line 13, in lambda_handler\n    bucket = event['Records'][0]['s3']['bucket']['name']\n"
  ]
}

Function Logs

START RequestId: 5c89bb8e-a70e-4c33-ba00-43174095544e Version: $LATEST
[ERROR] KeyError: 'Records'
Traceback (most recent call last):
  File "/var/task/lambda_function.py", line 13, in lambda_handler
    bucket = event['Records'][0]['s3']['bucket']['name']
END RequestId: 5c89bb8e-a70e-4c33-ba00-43174095544e
REPORT RequestId: 5c89bb8e-a70e-4c33-ba00-43174095544e  Duration: 1.89 ms   Billed Duration: 2 ms   Memory Size: 128 MB Max Memory Used: 69 MB  Init Duration: 356.28 ms

Answer 1

The problem is that

bucket = event['Records'][0]['s3']['bucket']['name']

Doesn't exist. Check the event object when its been triggered from S3. If you want to test in console you need to pass a similarly shaped object as the event.