Monitoring and Logging on EC2 Keeping Your Node.js App Healthy in Production

Monitoring and Logging on EC2

Monitoring your Node.js app in production is essential for catching issues before they affect users. This guide covers PM2 monitoring, log management, and external monitoring tools.

PM2 Monitoring

PM2 provides built-in monitoring tools:

# Real-time monitoring (CPU, memory, logs)
pm2 monit

# View all processes and their status
pm2 status

# View logs (streaming)
pm2 logs devtinder-api

# View only error logs
pm2 logs devtinder-api --err

# View last 100 lines
pm2 logs devtinder-api --lines 100

# View process details
pm2 describe devtinder-api

PM2 Log Rotation

Without log rotation, PM2 logs can fill up your disk. Install the log rotation module:

pm2 install pm2-logrotate

Default settings:

• Max size: 10 MB per file
• Retain: 30 files
• Compress old logs: yes

Customize:

pm2 set pm2-logrotate:max_size 5M
pm2 set pm2-logrotate:retain 7
pm2 set pm2-logrotate:compress true

Nginx Logs

# Access log (every HTTP request)
sudo tail -f /var/log/nginx/access.log

# Error log
sudo tail -f /var/log/nginx/error.log

# Check for 4xx and 5xx errors
sudo grep -E " 4[0-9]{2} | 5[0-9]{2} " /var/log/nginx/access.log

Nginx log rotation is configured by default in /etc/logrotate.d/nginx.

System Logs

# System messages
sudo tail -f /var/log/syslog

# Authentication logs (SSH logins)
sudo tail -f /var/log/auth.log

# Check for failed SSH attempts
sudo grep "Failed password" /var/log/auth.log | tail -20

AWS CloudWatch Monitoring

Install the CloudWatch agent to send metrics and logs to AWS:

# Install CloudWatch agent
sudo apt install -y amazon-cloudwatch-agent

# Configure it
sudo /opt/aws/amazon-cloudwatch-agent/bin/amazon-cloudwatch-agent-config-wizard

CloudWatch can monitor:

• CPU utilization
• Memory usage (requires agent)
• Disk space
• Network traffic
• Custom application metrics

Set up alarms:

• CPU > 80% for 5 minutes
• Memory > 80% for 5 minutes
• Disk space < 10%
• 5xx error rate > 5%

External Uptime Monitoring

Use external services to monitor your app from outside:

UptimeRobot (free):

1. Go to https://uptimerobot.com
2. Add a monitor for https://yourdomain.com/api/health
3. Set check interval (5 minutes)
4. Get email/SMS alerts when it goes down

Pingdom (paid):

• More detailed monitoring
• Performance insights
• Status pages

Health Check Endpoint

Create a health check endpoint in your Node.js app:

router.get("/health", (req, res) => {
  res.json({
    status: "ok",
    uptime: process.uptime(),
    timestamp: new Date().toISOString(),
    environment: process.env.NODE_ENV
  });
});

This endpoint should:

• Return 200 when the app is healthy
• Not require authentication
• Be fast (no database queries)
• Include basic info (uptime, environment)

Error Tracking with Sentry

npm install @sentry/node

const Sentry = require("@sentry/node");

Sentry.init({
  dsn: process.env.SENTRY_DSN,
  environment: process.env.NODE_ENV
});

// Express error handler
app.use(Sentry.Handlers.errorHandler());
app.use((err, req, res, next) => {
  res.status(err.statusCode || 500).json({ message: err.message });
});

Sentry captures unhandled errors, sends alerts, and provides a dashboard for tracking issues.

Performance Monitoring with PM2 Plus

pm2 plus

PM2 Plus (paid) provides:

• Real-time metrics dashboard
• Memory leak detection
• Event tracking
• Distributed tracing
• Exception reporting

Log Aggregation

For production, send logs to a centralized service:

CloudWatch Logs:

# Configure CloudWatch agent to send PM2 logs
sudo nano /opt/aws/amazon-cloudwatch-agent/bin/config.json

ELK Stack (Elasticsearch, Logstash, Kibana):

• Self-hosted log aggregation
• Powerful search and visualization
• Requires separate server

Datadog:

• Cloud-based monitoring
• APM (Application Performance Monitoring)
• Log management
• Paid service

The Takeaway

Monitoring your EC2 Node.js app involves: PM2 built-in monitoring (pm2 monit, pm2 logs), log rotation (pm2-logrotate), Nginx access and error logs, system logs, AWS CloudWatch for metrics and alarms, external uptime monitoring (UptimeRobot), a /health endpoint, error tracking with Sentry, and log aggregation. Set up alerts so you know about issues before your users do.