Read AWS s3 Bucket Name from CloudWatch Event - amazon-web-services

Question

I am working on writing a Lambda function that triggers when a new s3 bucket is created. I have a cloudwatch function that triggers the lambda function. I see the open to pass the whole event to the lambda function as input. When I this, how do I get my Lambda function to read the bucket's name from the event and assign the name as the value to a string variable?
Here is what my code looks like:
import boto3
from botocore.exceptions import ClientError
s3 = boto3.client('s3')
def lambda_handler(event, context):
bucket = event['s3']['bucket']['name']

Answer 1

CloudTrail events of S3 bucket level operations have different format than the one posted by #Woodrow. Actually, the name of bucket is within a JSON object called requestParameters. Moreover, the whole event is encapsulated within Records array. See CloudTrail Log Event Reference
Truncated version of CloudTrail event for bucket creation
"eventSource": "s3.amazonaws.com",
"eventName": "CreateBucket",
"userAgent": "signin.amazonaws.com",
"requestParameters": {
"CreateBucketConfiguration": {
"LocationConstraint": "aws-region",
"xmlns": "http://s3.amazonaws.com/doc/2006-03-01/"
},
"bucketName": "my-awsome-bucket"
}
Therefore, your code could look something like:
import boto3
from botocore.exceptions import ClientError
s3 = boto3.client('s3')
def lambda_handler(event, context):
for record in event['Records']:
if record['eventName'] == "CreateBucket":
bucket = record['requestParameters']['bucketName']
print(bucket)