从 S3 中删除 object 时触发 Lambda function

Question

I have an SFTP server and Lambda function. Lambda function is triggered when an object is uploaded to S3 and the object is automatically uploaded to SFTP server via SFTP. (I'm using pysftp)

Is it possible to create a Lambda function that will trigger once the object gets deleted from S3 and to delete it automatically from the server?

import pysftp,os,boto3

cnopts = pysftp.CnOpts()
cnopts.hostkeys = None

myHostname = os.environ.get('SFTP_HOST')
myUsername = os.environ.get('SFTP_USER')
myPassword = os.environ.get('SFTP_PASS')

s3 = boto3.client("s3")

def lambda_handler(event, context):

    # Get the records for the triggered event
    FILEOBJ = event["Records"][0]
    BUCKET_NAME = str(FILEOBJ['s3']['bucket']['name'])
    KEY = str(FILEOBJ['s3']['object']['key'])
    FILE_NAME = os.path.basename(KEY)
    TMP_FILE_NAME = '/tmp/' +FILE_NAME

    # Download the file/s from the event (extracted above) to the tmp location
    s3.download_file(BUCKET_NAME, KEY, TMP_FILE_NAME)

    with pysftp.Connection(host=myHostname, username=myUsername, password=myPassword, cnopts=cnopts) as sftp:
      with sftp.cd('data/uploads'):
        localFilePath = TMP_FILE_NAME
        sftp.remove(localFilePath)

Answer 1

You can use S3 event with Event type s3:ObjectRemoved:* and trigger Lambda functions.

https://docs.aws.amazon.com/AmazonS3/latest/userguide/notification-how-to-event-types-and-destinations.html

If you want to use the same function with S3 upload, you can find and use the info in event that Lambda function get like eventName': 'ObjectCreated:Put or eventName': 'ObjectRemoved:Delete .