Lambda with S3 trigger returning NoSuchKey error (Python)-CodePudding

I followed this tutorial to set up my Lambda that gets triggered when a file is uploaded to my S3 bucket: https://docs.aws.amazon.com/lambda/latest/dg/with-s3-example.html

I also set a prefix (which the tutorial doesn't have) so that only one folder is targeted: Prefix: posters/

I have a folder in my S3 bucket called posters/. Anyway, the code is directly copied from the tutorial:

import json
import urllib.parse
import boto3

print('Loading function')

s3 = boto3.client('s3', 'us-east-2')


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

And the test event has been configured as follows:

{
  "Records": [
    {
      "eventVersion": "2.0",
      "eventSource": "aws:s3",
      "awsRegion": "us-east-2",
      "eventTime": "1970-01-01T00:00:00.000Z",
      "eventName": "ObjectCreated:Put",
      "userIdentity": {
        "principalId": "EXAMPLE"
      },
      "requestParameters": {
        "sourceIPAddress": "127.0.0.1"
      },
      "responseElements": {
        "x-amz-request-id": "EXAMPLE123456789",
        "x-amz-id-2": "EXAMPLE123/5678abcdefghijklambdaisawesome/mnopqrstuvwxyzABCDEFGH"
      },
      "s3": {
        "s3SchemaVersion": "1.0",
        "configurationId": "testConfigRule",
        "bucket": {
          "name": "MY_BUCKET_NAME",
          "ownerIdentity": {
            "principalId": "EXAMPLE"
          },
          "arn": "arn:aws:s3:::example-bucket"
        },
        "object": {
          "key": "posters/HappyFace.jpg",
          "size": 1024,
          "eTag": "0123456789abcdef0123456789abcdef",
          "sequencer": "0A1B2C3D4E5F678901"
        }
      }
    }
  ]
}

When I test this, I get the following error:

{
  "errorMessage": "An error occurred (NoSuchKey) when calling the GetObject operation: The specified key does not exist.",
  "errorType": "NoSuchKey",
  "stackTrace": [
    "  File \"/var/task/lambda_function.py\", line 23, in lambda_handler\n    raise e\n",
    "  File \"/var/task/lambda_function.py\", line 17, in lambda_handler\n    response = s3.get_object(Bucket=bucket, Key=key)\n",
    "  File \"/var/runtime/botocore/client.py\", line 386, in _api_call\n    return self._make_api_call(operation_name, kwargs)\n",
    "  File \"/var/runtime/botocore/client.py\", line 705, in _make_api_call\n    raise error_class(parsed_response, operation_name)\n"
  ]
}

What exactly am I doing wrong here? Obviously the permissions are fine, since that issue went away after setting the right policy to the function role. Any help is greatly appreciated.

CodePudding user response：

NoSuchKey means the file isn't where the bucket key shows it should be.

Did you upload a test file named HappyFace.jpg inside the posters folder in your bucket (as per the tutorial Create a bucket and upload a sample object)?