Introduction

To ensure consistent sensor data collection for the ThriveWell project, I implemented an auto-notification system using AWS Lambda and EventBridge (CloudWatch Scheduler). The goal was to send timely reminders to users who haven't uploaded data recently — specifically those who haven't sent a heartbeat signal within the last 30 minutes.

This system works by:

• Querying DynamoDB to find devices with stale heartbeats
• Sending high-priority push notifications via Firebase Cloud Messaging (FCM)
• Running on a strict schedule: every 30 minutes between 9AM and 9PM (Eastern Time) daily

Through this setup, the system ensures passive sensing is maintained without manual intervention, enhancing both data reliability and user engagement

Implementation Steps

Lambda Function

1. Upload zip folder including node_modules, package.json, index.js (notification sending logic) (Notification sending & Heartbeat checking functionalities was implemented via AWS Lambda by Rahul, so I just copy & pasted relevent code in the lambda functions)
2. Set configurations and evironment variables:

   • Configuration Change: 30 sec

   • Environment Variables:

     DEVICE_TABLE	thrivewell-service-dev-devices
     FIREBASE_CONFIG	{your firebase config}

IAM Role

• Go to IAM > Roles and search for auto-notification-for-inactive-users-role-ef9t71kr

• Add permissions > Create inline policy

  {
  	"Version": "2012-10-17",
  	"Statement": [
  		{
  			"Effect": "Allow",
  			"Action": [
  				"dynamodb:Scan",
  				"dynamodb:GetItem"
  			],
  			"Resource": "arn:aws:dynamodb:us-east-1:992382461970:table/thrivewell-service-dev-devices"
  		}
  	]
  }