Pulsetic to SMS

AWS Lambda function that receives Pulsetic alerts and sends SMS notifications via Twilio.

Overview

This project creates an AWS Lambda function with a public function URL that can receive webhook notifications from Pulsetic monitoring service. When an alert is received, it automatically sends an SMS notification using Twilio.

Features

• 🚨 Receives Pulsetic webhook alerts
• 📱 Sends SMS notifications via Twilio
• ☁️ Serverless AWS Lambda deployment
• 🔧 Infrastructure as Code with Terraform
• 🌐 Public function URL (no API Gateway needed)

Prerequisites

• AWS CLI configured with appropriate permissions
• Terraform installed (>= 1.0)
• Node.js and npm installed
• Twilio account with phone number

Setup

1. Clone and navigate to the project:

   cd pulsetic-to-sms

2. Install dependencies:

   npm install

3. Configure Twilio and AWS settings:

   cp terraform.tfvars.example terraform.tfvars

   Edit terraform.tfvars with your actual values:

   • twilio_account_sid: Your Twilio Account SID
   • twilio_auth_token: Your Twilio Auth Token
   • twilio_from_number: Your Twilio phone number
   • to_number: Phone number to receive alerts

4. Deploy the infrastructure:

   chmod +x deploy.sh
   ./deploy.sh

5. Configure Pulsetic webhook:

   • Copy the Lambda Function URL from the deployment output
   • Add it as a webhook URL in your Pulsetic dashboard

Usage

Once deployed, the Lambda function will automatically:

1. Receive POST requests from Pulsetic with alert data
2. Parse the alert type and monitor information
3. Format SMS messages with relevant details (monitor name, URL, status, response codes)
4. Send SMS notifications to the configured phone number
5. Return a success/error response to Pulsetic

Supported Alert Types

The function handles different Pulsetic alert types:

• monitor_offline: 🚨 Alert when a monitor goes offline with response code and failure reason
• monitor_online: ✅ Alert when a monitor comes back online
• Other alerts: 📊 Generic alert format with monitor details

Expected Pulsetic Payload

The function expects Pulsetic alerts in this format:

{
  "alert_type": "monitor_offline",
  "monitor": {
    "id": 74710,
    "url": "https://example.com",
    "name": "Example Monitor",
    "response_code": 500,
    "fail_reason": "Connection timeout"
  }
}

Payload Fields

• alert_type: Type of alert (e.g., "monitor_offline", "monitor_online")
• monitor.id: Unique monitor identifier
• monitor.url: The URL being monitored
• monitor.name: Human-readable monitor name
• monitor.response_code: HTTP response code (for offline alerts)
• monitor.fail_reason: Reason for failure (for offline alerts)

SMS Message Format

SMS messages are formatted based on the alert type:

Monitor Offline:

🚨 Monitor Offline: [Monitor Name]
URL: [URL]
Response Code: [Code]
Reason: [Fail Reason]

Monitor Online:

✅ Monitor Online: [Monitor Name]
URL: [URL]
Monitor is back online

Architecture

• AWS Lambda: Serverless function to process webhooks
• Lambda Function URL: Direct HTTP endpoint (no API Gateway needed)
• Twilio: SMS service provider
• Terraform: Infrastructure as Code for deployment

Environment Variables

The Lambda function uses these environment variables (set via Terraform):

• TWILIO_ACCOUNT_SID: Twilio Account SID
• TWILIO_AUTH_TOKEN: Twilio Auth Token
• TWILIO_FROM_NUMBER: Twilio phone number to send from
• TO_NUMBER: Phone number to receive notifications

Monitoring

CloudWatch logs are automatically created for the Lambda function at: /aws/lambda/pulsetic-to-sms

Cleanup

To destroy all resources:

terraform destroy

Security Notes

• The function URL is public but only accepts POST requests
• Twilio credentials are stored as environment variables
• CloudWatch logs retention is set to 14 days
• All sensitive variables are marked as sensitive in Terraform

Cost

This solution uses AWS Lambda's free tier (1M requests/month) and minimal CloudWatch logging. Costs are primarily from:

• Lambda execution time (very minimal)
• Twilio SMS charges
• Minimal CloudWatch storage