如何在AWS中捕获Stream事件 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 )

Answer 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.

Answer 2

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.