AWS Lambda and Python

AWS Lambda is a server less computing platform. You can execute your code without provisioning or managing servers.

Tested an example of copying a text file dropped into one S3 bucket to another.

1. Create a IAM role with the CloudWatch and S3 policies.
Call role lambda_s3 and add policies: AWSOpsWorksCloudWatchLogs, AmazonS3FullAccess
2. Create two S3 buckets for source and target.
3. Create Lambda function for Copying a file from one bucket to another.
Author from scratch, Name = copyS3toS3 Python2.7, Existing Role = lambda_s3
Add S3 from left selections
Trigger select the source bucket, Object Created(All), Suffix = .txt, Check Enable Trigger
Click on function copyS3toS3 and add python code as showed in Appendix A
4. Save the Lambda function and upload a text file to the source s3 bucket to test.
5. You can go to Cloudwatch logs to root cause if test .txt file not showing up in target.

Appendix A: Lambda function python code
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from __future__ import print_function

import json
import boto3
import time
import urllib

print('Loading function')

s3 = boto3.client("s3")

def lambda_handler(event,context):
  source_bucket = event['Records'][0]['s3']['bucket']['name']
  key = urllib.unquote_plus(event['Records'][0]['s3']['object']['key'])
  target_bucket = 'iqonda-test02'  # target s3 bucket name
  copy_source = {'Bucket':source_bucket, 'Key':key}
  
  try:
    print('Waiting for the file persist in the source bucket')
    waiter = s3.get_waiter('object_exists')
    waiter.wait(Bucket=source_bucket, Key=key)
    print('Copying object from source s3 bucket to target s3 bucket')
    s3.copy_object(Bucket=target_bucket, Key=key, CopySource=copy_source)
  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

Appendix B:
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https://gist.github.com/anonymous/0f6b21d1586bd291d4ad0cc84c6383bb#file-s3-devnull-py