Handling S3 Bucket Trigger Event in Lambda Using Python

Question

The AWS Lambda handler has a signature of

def lambda_handler(event, context):

However, I cannot find any documentation as to the event's structure when the trigger is an S3 Bucket receiving a put

I thought that it might be defined in the s3 console, but couldn't find that there.

Anyone have any leads?

Answer 1

The event from S3 to Lambda function will be in json format as shown below,

{  
   "Records":[  
      {  
         "eventVersion":"2.0",
         "eventSource":"aws:s3",
         "awsRegion":"us-east-1",
         "eventTime":The time, in ISO-8601 format, for example, 1970-01-01T00:00:00.000Z, when S3 finished processing the request,
         "eventName":"event-type",
         "userIdentity":{  
            "principalId":"Amazon-customer-ID-of-the-user-who-caused-the-event"
         },
         "requestParameters":{  
            "sourceIPAddress":"ip-address-where-request-came-from"
         },
         "responseElements":{  
            "x-amz-request-id":"Amazon S3 generated request ID",
            "x-amz-id-2":"Amazon S3 host that processed the request"
         },
         "s3":{  
            "s3SchemaVersion":"1.0",
            "configurationId":"ID found in the bucket notification configuration",
            "bucket":{  
               "name":"bucket-name",
               "ownerIdentity":{  
                  "principalId":"Amazon-customer-ID-of-the-bucket-owner"
               },
               "arn":"bucket-ARN"
            },
            "object":{  
               "key":"object-key",
               "size":object-size,
               "eTag":"object eTag",
               "versionId":"object version if bucket is versioning-enabled, otherwise null",
               "sequencer": "a string representation of a hexadecimal value used to determine event sequence, 
                   only used with PUTs and DELETEs"            
            }
         }
      },
      {
          // Additional events
      }
   ]
}

here is the link for aws documentation which can guide you. http://docs.aws.amazon.com/lambda/latest/dg/with-s3-example.html