带有 S3 触发器的 Lambda 返回 NoSuchKey 错误（Python）

Question

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.

Answer 1

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 )?