Get emails whenever a file is uploaded on s3 bucket using serverless - python-2.7

Question

i want to get emails whenever a file is uploaded to s3 bucket as described in the title above, i am using serverless, the issue is that the event that i have created on s3 gives me just notification on s3-aws console, and don't know how to configure cloudwatch event on S3 to trigger lambda. So please if someone knows how to triggered events on S3 using cloudwatch i am all ears.
Here is my code:
import json
import boto3
import botocore
import logging
import sys
import os
import traceback
from botocore.exceptions import ClientError
from pprint import pprint
from time import strftime, gmtime
email_from = '*****#******.com'
email_to = '******#******.com'
#email_cc = '********#gmail.com'
email_subject = 'new event on s3 '
email_body = 'a new file is uploaded'
#setup simple logging for INFO
logger = logging.getLogger()
logger.setLevel(logging.INFO)
from botocore.exceptions import ClientError
def sthree(event, context):
"""Send email whenever a file is uploaded to S3"""
body = {}
status_code = 200
try:
s3 = boto3.client('s3')
ses = boto3.client('ses')
response = ses.send_email(Source = email_from,
Destination = {'ToAddresses': [email_to,],},
Message = {'Subject': {'Data': email_subject}, 'Body':{'Text' : {'Data': email_body}}}
)
response = {
"statusCode": 200,
"body": json.dumps(body)
}
return response
and here is my serverless.yml file
service: aws-python # NOTE: update this with your service name
plugins:
- serverless-external-s3-event
provider: name: aws
runtime: python2.7
stage: dev
region: us-east-1
iamRoleStatements:
- Effect: "Allow"
Action:
- s3:*
- "ses:SendEmail"
- "ses:SendRawEmail"
- "s3:PutBucketNotification"
Resource: "*"
functions: sthree:
handler: handler.sthree
description: send mail whenever a file is uploaded on S3
events:
- s3:
bucket: cartegie-nirmine
event: s3:ObjectCreated:*
rules:
- prefix: uploads/
- suffix: .jpg
- cloudwatchEvent:
description: 'CloudWatch Event triggered '
event:
source:
- "aws.S3"
detail-type:
- "S3 event Notification"
enabled : true

Answer 1

If your motto is just to receive email notification of operations on a S3 bucket, then you dont need lambda functions for that. For the use-case mentioned in the question, you can achieve that using SNS topic and S3 events. I will mention the steps to follow from console(through the same can be achieved via sdk or cli).
1) Create a Topic using SNS console.
2) Subscribe to the topic. Use email as the communications protocol and provide your email-id.
3) You will get email requesting you to confirm your subscription to the topic. Confirm the subscription.
4) IMPORTANT: Replace the access policy of the topic with the below policy:
{
"Version": "2008-10-17",
"Id": "__default_policy_ID",
"Statement": [
{
"Sid": "__default_statement_ID",
"Effect": "Allow",
"Principal": {
"AWS": "*"
},
"Action": "SNS:Publish",
"Resource": "sns-topic-arn",
"Condition": {
"ArnLike": {
"aws:SourceArn": "arn:aws:s3:*:*:s3-bucket-name"
}
}
}
]
}
Basically you are giving permission for your s3-bucket to publish to the SNS topic.
Replace sns-topic-arn with your ARN of the topic you created above.
Replce s3-bucket-name with your bucket name, for which you want to receive notifications.
5) Go to S3 Console. Click on your S3 bucket and open the Properties tab.
6) Under Advanced settings, Click on Events Card.
7) Click Add Notifications and enter values. A sample has been shown below.
Select the required s3-events to monitor and the SNS topic you created.
8) Click Save. Now you should start receiving notifications to your email.