How to capture the Stream event in AWS lambda python

Question

I have dynamo db which name as "test-dynamo"

I have enable Manage stream

I need to capture in lambda function. If any update/Insert has happend to this dynamo table I need to see in the lambda

def gettable(table_name, dynamodb_client):
        response = dynamodb_client.get_item(
            TableName=table_name,
            Key={
                'id': {'S': key
                            }})
        return response

def lambda_handler(event, context):
    dynamodb_client = boto3.client('dynamodb')
    boto3.resource('dynamodb')
    res= gettable("test-dynamo",dynamodb_client )
    print('event', event )

samtoddler · Accepted Answer · 2021-01-13 13:12:05Z

1

You can checkout this documentation page for configuring the same.

for example once you subscirbe your lambda function to the corresponding dynamodb stream you create in cloudformation,

    rLoggingFunction:
        Type: AWS::Lambda::Function
        Properties:
        Runtime: python3.7
        Timeout: '300'
        Handler: index.handler
        Role: !GetAtt rLambdaRole.Arn
        Code:
            ZipFile: |
            import logging

            LOGGER = logging.getLogger()
            LOGGER.setLevel(logging.INFO)

            def handler(event, context):
                LOGGER.info('Received Event: %s', event)
                for rec in event['Records']:
                LOGGER.info('Record: %s', rec) 
    ....
    rDynamoDBTable:
        Type: AWS::DynamoDB::Table
        Properties:
        AttributeDefinitions:
            - AttributeName: id
            AttributeType: S
        KeySchema:
            - AttributeName: id
            KeyType: HASH
        ProvisionedThroughput:
            ReadCapacityUnits: 1
            WriteCapacityUnits: 1
        StreamSpecification:
            StreamViewType: NEW_AND_OLD_IMAGES

    rDynamoDBTableStream:
        Type: AWS::Lambda::EventSourceMapping
        Properties:
        # The maximum number of DB items to send to Lambda
        BatchSize: 1
        Enabled: True
        EventSourceArn: !GetAtt rDynamoDBTable.StreamArn
        FunctionName: !GetAtt rLoggingFunction.Arn
        # Always start at the tail of the Stream
        StartingPosition: LATEST

There is a full example via serverless for the same.

edited Jan 13, 2021 at 13:12

answered Jan 13, 2021 at 13:06

samtoddler

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2 Comments

user14257643 Over a year ago

in python lambda, how to capture the dynamo db stream events

samtoddler Over a year ago

from documentation >Create an event source mapping in AWS Lambda. This event source mapping associates the DynamoDB stream with your Lambda function. After you create this event source mapping, AWS Lambda starts polling the stream. They will be delivered to your trigger like lambda we are configuring in this case automatically.

Ranopriyo Neogy · Accepted Answer · 2021-06-29 23:14:46Z

-1

You can do it using simple code once you enable stream in DynamoDB:

import json
import boto3
from boto3.dynamodb.conditions import Key
def lambda_handler(event, context):
      print('##Below Event occured')
      print(event)

This will print the latest event in cloudwatch logs.

answered Jun 29, 2021 at 23:14

Ranopriyo Neogy

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