🚀 Render Keep-Alive Worker

A production-ready Cloudflare Worker that automatically pings your Render applications every 14 minutes during business hours (7 AM - 12 PM IST) to prevent them from going to sleep on the free tier.

🎯 Problem & Solution

The Challenge: Render's free tier puts applications to sleep after 15 minutes of inactivity, resulting in cold starts and slow response times for users.

The Solution: This intelligent worker pings your application every 14 minutes during peak business hours, ensuring optimal availability when your users need it most while conserving resources during off-peak times.

✨ Features

• 🆓 Zero Cost - Runs entirely on Cloudflare's generous free tier
• ⏰ Smart Scheduling - Active only during business hours (7 AM - 12 PM IST)
• 🛡️ Production Ready - Comprehensive error handling, retry logic, and timeout protection
• 📊 Detailed Monitoring - Rich logging and status endpoints for observability
• 🔧 Zero Maintenance - Set once, runs automatically
• ⚡ Quick Deploy - Ready in under 5 minutes
• 🔄 Configurable - Customizable endpoints, timeouts, and schedules

🚀 Quick Start

Prerequisites

• Node.js (v16 or later)
• Git
• Cloudflare account (free)
• Render application URL

1. Clone & Setup

# Clone the repository
git clone https://github.com/kavinthangavel/cloudflare-render-ping.git

cd cloudflare-render-ping

# Install dependencies
npm install

# Install Wrangler CLI (if not already installed)
npm install wrangler --save-dev

2. Configure Cloudflare

# Login to Cloudflare (opens browser for authentication)
npx wrangler login

# Set your Render application URL as a secret
npx wrangler secret put RENDER_APP_URL
# When prompted, enter: https://your-app.onrender.com

3. Deploy

# Deploy the worker to Cloudflare
npx wrangler deploy

# Your worker will be available at:
# https://render-ping-worker.your-subdomain.workers.dev

4. Verify Deployment

# Test the worker manually
curl https://your-worker.workers.dev/ping

# View real-time logs
npx wrangler tail

# Check configuration
curl https://your-worker.workers.dev/debug

📋 CLI Commands Reference

Here are all the commands used during development and deployment:

Wrangler Commands

# Authentication
npx wrangler login                    # Login to Cloudflare
npx wrangler whoami                   # Check current user

# Secrets Management
npx wrangler secret list              # List all secrets
npx wrangler secret put RENDER_APP_URL # Set application URL
npx wrangler secret delete {SECRET_NAME} # Remove a secret

# Deployment
npx wrangler deploy                   # Deploy to production
npx wrangler deploy --dry-run         # Preview deployment
npx wrangler deploy --name custom-name # Deploy with custom name

# Monitoring & Debugging
npx wrangler tail                     # View real-time logs
npx wrangler tail --format pretty    # Formatted log output
npx wrangler dev                      # Run locally for development

# Configuration
npx wrangler generate --template worker # Generate new worker
npx wrangler init                     # Initialize new project

Testing Commands

# Test endpoints
curl https://your-worker.workers.dev/                # Status page
curl https://your-worker.workers.dev/ping           # Manual ping
curl https://your-worker.workers.dev/debug          # Debug info

# Test with PowerShell (Windows alternative)
Invoke-RestMethod -Uri "https://your-worker.workers.dev/ping"
Invoke-WebRequest -Uri "https://your-worker.workers.dev/" | Select-Object Content

🔧 Configuration

Environment Variables

Variable	Required	Default	Description
RENDER_APP_URL	✅	-	Your Render application URL
HEALTH_ENDPOINT	❌	/healthz	Health check endpoint path
TIMEOUT_MS	❌	30000	Request timeout (milliseconds)
RETRY_ATTEMPTS	❌	2	Number of retry attempts

Setting Environment Variables

# Required: Set your Render app URL
npx wrangler secret put RENDER_APP_URL

# Optional: Customize health endpoint
npx wrangler secret put HEALTH_ENDPOINT
# Enter: /api/health (or your preferred endpoint)

# Optional: Increase timeout for slow apps
npx wrangler secret put TIMEOUT_MS
# Enter: 60000 (for 60 seconds)

# Optional: Adjust retry attempts
npx wrangler secret put RETRY_ATTEMPTS
# Enter: 3 (for 3 retry attempts)

Schedule Customization

Edit wrangler.toml to modify the ping schedule:

[triggers]
# Current: Every 14 minutes, 7 AM - 12 PM IST
crons = ["*/14 1-6 * * *"]

# Examples:
# Every 14 minutes, 24/7
crons = ["*/14 * * * *"]

# Every 15 minutes, weekdays only, 9 AM - 5 PM UTC
crons = ["*/15 9-17 * * 1-5"]

# Every 5 minutes, business hours extended
crons = ["*/5 0-8 * * *"]  # 5:30 AM - 1:30 PM IST

📊 Monitoring & Endpoints

Available Endpoints

Endpoint	Method	Description	Example Response
/	GET	Status dashboard	HTML page with configuration
/ping	GET/POST	Manual health check	{"success": true, "message": "Health check triggered"}
/debug	GET	Environment variables	{"environment_variables": {...}}

Monitoring Commands

# Real-time log monitoring
npx wrangler tail --format pretty

# Check worker analytics (in dashboard)
# Visit: https://dash.cloudflare.com/workers

# Test all endpoints
curl https://your-worker.workers.dev/
curl https://your-worker.workers.dev/ping
curl https://your-worker.workers.dev/debug

Log Messages

• 🚀 Starting health check - Worker initiated
• ✅ Health check successful! - Successful ping with response time
• ⚠️ Server responded but status unclear - Response received but unexpected format
• ❌ HTTP Error: XXX - Server returned error status
• ⏱️ Request timeout - Request exceeded timeout limit
• 🌐 Network error - Connection or DNS issues
• 💔 All attempts failed - All retries exhausted

🏥 Health Check Endpoint Setup

For Your Render Application

Add a health check endpoint to your Render app for optimal monitoring:

Node.js/Express

app.get('/healthz', (req, res) => {
  res.status(200).json({ 
    status: 'ok', 
    timestamp: new Date().toISOString(),
    uptime: process.uptime(),
    memory: process.memoryUsage()
  });
});

Python/Flask

from datetime import datetime
import psutil

@app.route('/healthz')
def health_check():
    return {
        'status': 'ok',
        'timestamp': datetime.now().isoformat(),
        'uptime': time.time() - psutil.boot_time(),
        'memory': psutil.virtual_memory()._asdict()
    }

Python/FastAPI

from datetime import datetime
from fastapi import FastAPI

@app.get("/healthz")
async def health_check():
    return {
        "status": "ok",
        "timestamp": datetime.now().isoformat(),
        "service": "My Render App"
    }

Alternative: Use Existing Endpoints

If you don't want to add a dedicated health endpoint:

# Use homepage
npx wrangler secret put HEALTH_ENDPOINT
# Enter: /

# Use existing API endpoint
npx wrangler secret put HEALTH_ENDPOINT
# Enter: /api/status

🔍 Troubleshooting

Common Issues & Solutions

❌ Environment Variable Not Found

# Problem: Worker shows "Not configured"
# Solution: Set the secret properly
npx wrangler secret put RENDER_APP_URL
# Enter your full Render URL: https://your-app.onrender.com

# Verify it was set
npx wrangler secret list

❌ Deployment Failures

# Problem: "No fetch handler" error
# Solution: Check your main entry point in wrangler.toml
# Ensure: main = "src/index.js"

# Problem: Wrangler login issues
# Solution: Clear auth and re-login
npx wrangler logout
npx wrangler login

❌ Health Check Failures

# Problem: "All attempts failed"
# Solution: Test your Render URL manually
curl https://your-app.onrender.com/healthz

# If 404, try homepage instead
npx wrangler secret put HEALTH_ENDPOINT
# Enter: /

❌ Worker Not Running

# Check deployment status
npx wrangler tail

# Verify cron schedule is correct
Get-Content wrangler.toml

# Test manual trigger
curl https://your-worker.workers.dev/ping

Debug Commands

# Check worker configuration
curl https://your-worker.workers.dev/debug

# View deployment info
npx wrangler dev --local-protocol https

# Check if secrets are set
npx wrangler secret list

# Test Render app directly
curl https://your-app.onrender.com/healthz -v

💰 Cost Analysis

Cloudflare Workers (Free Tier)

• ✅ 100,000 requests/day included
• ✅ ~103 requests/day used (7×14.7 pings×5 weekdays)
• ✅ Completely free for this use case
• ✅ 10ms CPU time per request (well under 10,000ms limit)

Render (Free Tier)

• ✅ 750 hours/month of runtime
• ✅ Stays awake during business hours only
• ✅ Sleeps at night to conserve hours
• ✅ No additional costs

🔄 Workflow Overview

1. Cron Trigger - Cloudflare's scheduler activates worker every 14 minutes
2. Environment Check - Worker validates configuration
3. Health Request - GET request sent to your Render app
4. Response Validation - Check for successful response
5. Retry Logic - Automatic retries on failure
6. Logging - Detailed logs for monitoring
7. Completion - Process repeats next cycle

🛠️ Development

Making Changes

# Edit the worker code
code src/index.js

# Update configuration
code wrangler.toml

# Deploy changes
npx wrangler deploy

# View updated logs
npx wrangler tail

Testing New Features

# Deploy to a staging environment
npx wrangler deploy --name render-ping-staging

# Test staging
curl https://render-ping-staging.your-subdomain.workers.dev/ping

# Deploy to production when ready
npx wrangler deploy

🤝 Contributing

1. Fork the repository
2. Create a feature branch: git checkout -b feature/amazing-feature
3. Commit changes: git commit -m 'Add amazing feature'
4. Push to branch: git push origin feature/amazing-feature
5. Open a Pull Request

---

🎯 Ready to keep your Render app alive? Follow the Quick Start guide above!