Add SNS Notification Support, Region Configuration, and Local Testing Script to MongoDB Backup Lambda

[harsha-at-magicshake]

Overview

This PR enhances the MongoDB backup Lambda function with the following features:

• SNS Notification Integration: The Lambda now sends notifications to an AWS SNS topic on both backup success and failure events.
• Configurable AWS Region: The AWS region is now configurable via environment variables, ensuring compatibility and proper functioning of the AWS SDK.
• Improved Error Handling: All critical failure points (directory creation, mongodump, zipping, S3 upload, retention logic) now trigger both Slack and SNS notifications if configured.
• Local Testing Script: Added test-local.js to allow local execution and debugging of the Lambda function.
• .env and Documentation Updates: The .env file and README have been updated to reflect new configuration options and usage instructions.

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Detailed Changes

1. index.js

• Added SNS client initialization with region support:

  const sns = new AWS.SNS({ region: process.env.AWS_REGION || "us-east-1" });

• Added a notifySNS helper function to send notifications to the configured SNS topic.
• Modified error handling and success completion logic to call notifySNS with appropriate messages.
• Ensured all notifications are sent asynchronously and errors in notification delivery are logged but do not interrupt the backup flow.

2. .env

• Added SNS_TOPIC_ARN for specifying the SNS topic to send notifications to.
• Added AWS_REGION for specifying the AWS region used by the SDK.

3. test-local.js

• Added a script to allow running and testing the Lambda backup logic locally.
• Loads environment variables from .env using dotenv.
• Calls the Lambda handler directly, simulating an AWS Lambda execution environment.

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How to Use

1. Configure Environment Variables:

   • Set SNS_TOPIC_ARN to your SNS topic ARN (e.g., arn:aws:sns:us-east-1:xxxxxxxxxxxx:mongodb-backup-events).
   • Set AWS_REGION to your preferred AWS region (e.g., us-east-1).

2. SNS Setup:

   • Create an SNS topic and subscribe your email or other endpoints.
   • Confirm your subscription as required.

3. Deploy & Test:

   • Deploy the updated Lambda function.
   • Trigger the Lambda (manually or via schedule) and verify you receive SNS notifications for both success and failure cases.
   • To test locally, run:

     node test-local.js

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Example .env Additions

SNS_TOPIC_ARN=arn:aws:sns:us-east-1:xxxxxxxxxxxx:mongodb-backup-events
AWS_REGION=us-east-1

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Files Changed

• index.js – Main Lambda logic, SNS integration, region support, improved error handling.
• .env – Added SNS and region configuration variables.
• test-local.js – Added for local development and debugging.

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Notes

• Slack notifications remain supported and are unaffected by these changes.
• If SNS_TOPIC_ARN is not set, SNS notifications are skipped with a warning.
• If AWS_REGION is not set, it defaults to us-east-1.