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Building event-driven architectures in the cloud is common and works well in many situations. You can loosely associate various components and sit back and wait for one action to trigger another. One component in AWS that works well for this is DynamoDB Streams.
You can set up your DynamoDB NoSQL database to emit events whenever changes occur in the database. These “streams” of events can then trigger other actions in your account. If you combine these with AWS Lambda serverless functions, you can perform almost any task or initiate almost any other service.
This example from LearnAWS provides more details around DynamoDB Streams and offers an example of logging database updates to CloudWatch logs using these.
Read the full DynamoDB Streams Tutorial here
You Should Know:
1. Enabling DynamoDB Streams via AWS CLI
To enable DynamoDB Streams on an existing table, use:
aws dynamodb update-table \ --table-name YourTableName \ --stream-specification StreamEnabled=true,StreamViewType=NEW_AND_OLD_IMAGES
2. Creating a Lambda Trigger for DynamoDB Streams
Deploy a Lambda function that processes DynamoDB events:
import json
def lambda_handler(event, context):
for record in event['Records']:
if record['eventName'] == 'INSERT':
print("New record inserted:", record['dynamodb']['NewImage'])
elif record['eventName'] == 'MODIFY':
print("Record modified:", record['dynamodb']['NewImage'])
elif record['eventName'] == 'REMOVE':
print("Record deleted:", record['dynamodb']['OldImage'])
return {'statusCode': 200}
3. Linking Lambda to DynamoDB Stream
Use AWS CLI to connect the Lambda function to the stream:
aws lambda create-event-source-mapping \ --function-name YourLambdaFunction \ --event-source-arn YourDynamoDBStreamARN \ --batch-size 100 \ --starting-position LATEST
4. Monitoring Stream Logs in CloudWatch
Check the logs generated by your Lambda function:
aws logs filter-log-events \ --log-group-name /aws/lambda/YourLambdaFunction \ --filter-pattern "Record"
5. Useful Linux Commands for Debugging AWS Streams
- Check AWS Lambda Logs:
tail -f /var/log/cloud-init-output.log
- List DynamoDB Tables with Streams Enabled:
aws dynamodb list-tables --query "TableNames[?contains(@,'YourPrefix')]"
- View Stream ARN:
aws dynamodb describe-table --table-name YourTableName --query "Table.LatestStreamArn"
What Undercode Say:
DynamoDB Streams provide a powerful way to track changes in real-time, enabling event-driven architectures in AWS. By integrating Lambda, you can automate workflows, log changes, and trigger downstream processes efficiently. Mastering DynamoDB Streams is essential for cloud architects and DevOps engineers working with serverless applications.
Expected Output:
- DynamoDB Streams enabled on a table.
- Lambda function processing INSERT, MODIFY, and REMOVE events.
- CloudWatch logs showing real-time database changes.
- Automated workflows triggered by DynamoDB updates.
For a deeper dive, refer to the official AWS DynamoDB Streams documentation.
References:
Reported By: Darryl Ruggles – Hackers Feeds
Extra Hub: Undercode MoN
Basic Verification: Pass ✅
