Implement Node.js application monitoring with Prometheus metrics collection and Grafana dashboards

Install Prometheus server

Download and install Prometheus to collect metrics from your Node.js applications.

cd /tmp
wget https://github.com/prometheus/prometheus/releases/download/v2.45.0/prometheus-2.45.0.linux-amd64.tar.gz
tar xzf prometheus-2.45.0.linux-amd64.tar.gz
sudo cp prometheus-2.45.0.linux-amd64/prometheus /usr/local/bin/
sudo cp prometheus-2.45.0.linux-amd64/promtool /usr/local/bin/
sudo mkdir -p /etc/prometheus /var/lib/prometheus
sudo cp -r prometheus-2.45.0.linux-amd64/consoles /etc/prometheus
sudo cp -r prometheus-2.45.0.linux-amd64/console_libraries /etc/prometheus

cd /tmp
wget https://github.com/prometheus/prometheus/releases/download/v2.45.0/prometheus-2.45.0.linux-amd64.tar.gz
tar xzf prometheus-2.45.0.linux-amd64.tar.gz
sudo cp prometheus-2.45.0.linux-amd64/prometheus /usr/local/bin/
sudo cp prometheus-2.45.0.linux-amd64/promtool /usr/local/bin/
sudo mkdir -p /etc/prometheus /var/lib/prometheus
sudo cp -r prometheus-2.45.0.linux-amd64/consoles /etc/prometheus
sudo cp -r prometheus-2.45.0.linux-amd64/console_libraries /etc/prometheus

Create Prometheus user and set permissions

Create a dedicated user for Prometheus and set correct ownership on configuration directories.

sudo useradd --no-create-home --shell /bin/false prometheus
sudo chown -R prometheus:prometheus /etc/prometheus /var/lib/prometheus
sudo chown prometheus:prometheus /usr/local/bin/prometheus /usr/local/bin/promtool

Configure Prometheus

Create the main Prometheus configuration file to scrape Node.js application metrics.

global:
  scrape_interval: 15s
  evaluation_interval: 15s

rule_files:
  - "/etc/prometheus/rules/*.yml"

alerting:
  alertmanagers:
    - static_configs:
        - targets:
          - localhost:9093

scrape_configs:
  - job_name: 'prometheus'
    static_configs:
      - targets: ['localhost:9090']

  - job_name: 'node-app'
    static_configs:
      - targets: ['localhost:3000']
    metrics_path: '/metrics'
    scrape_interval: 5s

  - job_name: 'node-exporter'
    static_configs:
      - targets: ['localhost:9100']

Create Prometheus systemd service

Set up Prometheus to run as a system service with automatic startup.

[Unit]
Description=Prometheus
Wants=network-online.target
After=network-online.target

[Service]
User=prometheus
Group=prometheus
Type=simple
ExecStart=/usr/local/bin/prometheus \
    --config.file /etc/prometheus/prometheus.yml \
    --storage.tsdb.path /var/lib/prometheus/ \
    --web.console.templates=/etc/prometheus/consoles \
    --web.console.libraries=/etc/prometheus/console_libraries \
    --web.listen-address=0.0.0.0:9090 \
    --web.enable-lifecycle

[Install]
WantedBy=multi-user.target

Install Node Exporter

Install Node Exporter to collect system metrics alongside application metrics.

cd /tmp
wget https://github.com/prometheus/node_exporter/releases/download/v1.6.1/node_exporter-1.6.1.linux-amd64.tar.gz
tar xzf node_exporter-1.6.1.linux-amd64.tar.gz
sudo cp node_exporter-1.6.1.linux-amd64/node_exporter /usr/local/bin/
sudo chown prometheus:prometheus /usr/local/bin/node_exporter

Create Node Exporter systemd service

Configure Node Exporter as a system service for system metrics collection.

[Unit]
Description=Node Exporter
Wants=network-online.target
After=network-online.target

[Service]
User=prometheus
Group=prometheus
Type=simple
ExecStart=/usr/local/bin/node_exporter

[Install]
WantedBy=multi-user.target

Install Prometheus client in Node.js application

Add the Prometheus client library to your Node.js application for metrics collection.

cd /path/to/your/node/app
npm install prom-client express-prometheus-middleware

Configure Node.js application metrics

Add Prometheus metrics collection to your Express.js application with custom performance tracking.

const express = require('express');
const client = require('prom-client');
const promMid = require('express-prometheus-middleware');

const app = express();

// Create a Registry which registers the metrics
const register = new client.Registry();

// Add a default label which is added to all metrics
register.setDefaultLabels({
  app: 'my-node-app'
});

// Enable the collection of default metrics
client.collectDefaultMetrics({ register });

// Custom metrics
const httpRequestDuration = new client.Histogram({
  name: 'http_request_duration_seconds',
  help: 'Duration of HTTP requests in seconds',
  labelNames: ['method', 'route', 'status'],
  buckets: [0.1, 0.3, 0.5, 0.7, 1, 3, 5, 7, 10]
});

const httpRequestsTotal = new client.Counter({
  name: 'http_requests_total',
  help: 'Total number of HTTP requests',
  labelNames: ['method', 'route', 'status']
});

const activeConnections = new client.Gauge({
  name: 'active_connections',
  help: 'Number of active connections'
});

const databaseConnections = new client.Gauge({
  name: 'database_connections',
  help: 'Number of database connections',
  labelNames: ['database', 'state']
});

// Register custom metrics
register.registerMetric(httpRequestDuration);
register.registerMetric(httpRequestsTotal);
register.registerMetric(activeConnections);
register.registerMetric(databaseConnections);

// Middleware to track request metrics
app.use((req, res, next) => {
  const start = Date.now();
  
  res.on('finish', () => {
    const duration = (Date.now() - start) / 1000;
    const route = req.route ? req.route.path : req.url;
    
    httpRequestDuration
      .labels(req.method, route, res.statusCode)
      .observe(duration);
    
    httpRequestsTotal
      .labels(req.method, route, res.statusCode)
      .inc();
  });
  
  next();
});

// Track active connections
app.use((req, res, next) => {
  activeConnections.inc();
  res.on('finish', () => activeConnections.dec());
  next();
});

// Metrics endpoint
app.get('/metrics', async (req, res) => {
  res.set('Content-Type', register.contentType);
  res.end(await register.metrics());
});

// Health check endpoint
app.get('/health', (req, res) => {
  res.json({ status: 'healthy', timestamp: new Date().toISOString() });
});

// Example route with custom metrics
app.get('/api/users', (req, res) => {
  // Simulate database connection tracking
  databaseConnections.labels('users_db', 'active').set(5);
  databaseConnections.labels('users_db', 'idle').set(3);
  
  res.json({ users: ['alice', 'bob', 'charlie'] });
});

const port = process.env.PORT || 3000;
app.listen(port, () => {
  console.log(`Server running on port ${port}`);
  console.log(`Metrics available at http://localhost:${port}/metrics`);
});

Install and configure Grafana

Install Grafana for creating dashboards and visualizing Prometheus metrics.

sudo apt update
sudo apt install -y software-properties-common
wget -q -O - https://packages.grafana.com/gpg.key | sudo apt-key add -
echo "deb https://packages.grafana.com/oss/deb stable main" | sudo tee /etc/apt/sources.list.d/grafana.list
sudo apt update
sudo apt install -y grafana

sudo dnf install -y https://dl.grafana.com/oss/release/grafana-10.1.1-1.x86_64.rpm

Start and enable services

Start all monitoring services and enable them to start automatically on boot.

sudo systemctl daemon-reload
sudo systemctl enable --now prometheus
sudo systemctl enable --now node_exporter
sudo systemctl enable --now grafana-server

# Verify services are running
sudo systemctl status prometheus
sudo systemctl status node_exporter
sudo systemctl status grafana-server

Configure Grafana data source

Add Prometheus as a data source in Grafana for metrics visualization.

# Access Grafana web interface at http://your-server:3000
# Default credentials: admin/admin

# Add Prometheus data source via API
curl -X POST \
  http://admin:admin@localhost:3000/api/datasources \
  -H 'Content-Type: application/json' \
  -d '{
    "name": "Prometheus",
    "type": "prometheus",
    "url": "http://localhost:9090",
    "access": "proxy",
    "isDefault": true
  }'

Create Node.js application dashboard

Import a comprehensive dashboard for Node.js application monitoring.

{
  "dashboard": {
    "id": null,
    "title": "Node.js Application Monitoring",
    "tags": ["nodejs", "prometheus"],
    "timezone": "browser",
    "panels": [
      {
        "id": 1,
        "title": "HTTP Request Rate",
        "type": "graph",
        "targets": [
          {
            "expr": "rate(http_requests_total[5m])",
            "legendFormat": "{{method}} {{route}}"
          }
        ],
        "gridPos": {"h": 8, "w": 12, "x": 0, "y": 0}
      },
      {
        "id": 2,
        "title": "HTTP Request Duration",
        "type": "graph",
        "targets": [
          {
            "expr": "histogram_quantile(0.95, rate(http_request_duration_seconds_bucket[5m]))",
            "legendFormat": "95th percentile"
          },
          {
            "expr": "histogram_quantile(0.50, rate(http_request_duration_seconds_bucket[5m]))",
            "legendFormat": "50th percentile"
          }
        ],
        "gridPos": {"h": 8, "w": 12, "x": 12, "y": 0}
      },
      {
        "id": 3,
        "title": "Active Connections",
        "type": "singlestat",
        "targets": [
          {
            "expr": "active_connections",
            "legendFormat": "Connections"
          }
        ],
        "gridPos": {"h": 4, "w": 6, "x": 0, "y": 8}
      },
      {
        "id": 4,
        "title": "Memory Usage",
        "type": "graph",
        "targets": [
          {
            "expr": "process_resident_memory_bytes",
            "legendFormat": "RSS Memory"
          },
          {
            "expr": "nodejs_heap_size_used_bytes",
            "legendFormat": "Heap Used"
          }
        ],
        "gridPos": {"h": 8, "w": 12, "x": 6, "y": 8}
      }
    ],
    "time": {"from": "now-1h", "to": "now"},
    "refresh": "5s"
  }
}

# Import dashboard via API
curl -X POST \
  http://admin:admin@localhost:3000/api/dashboards/db \
  -H 'Content-Type: application/json' \
  -d @/tmp/nodejs-dashboard.json

Configure alerting rules

Set up Prometheus alerting rules for Node.js application monitoring.

sudo mkdir -p /etc/prometheus/rules

groups:
  - name: nodejs_alerts
    rules:
      - alert: HighRequestLatency
        expr: histogram_quantile(0.95, rate(http_request_duration_seconds_bucket[5m])) > 0.5
        for: 5m
        labels:
          severity: warning
        annotations:
          summary: "High request latency on Node.js application"
          description: "95th percentile latency is {{ $value }}s for more than 5 minutes"
      
      - alert: HighErrorRate
        expr: rate(http_requests_total{status=~"5.."}[5m]) > 0.1
        for: 2m
        labels:
          severity: critical
        annotations:
          summary: "High error rate on Node.js application"
          description: "Error rate is {{ $value }} errors per second"
      
      - alert: MemoryUsageHigh
        expr: process_resident_memory_bytes > 500000000
        for: 5m
        labels:
          severity: warning
        annotations:
          summary: "High memory usage on Node.js application"
          description: "Memory usage is {{ $value | humanize }}B"
      
      - alert: NodeJSDown
        expr: up{job="node-app"} == 0
        for: 1m
        labels:
          severity: critical
        annotations:
          summary: "Node.js application is down"
          description: "Node.js application has been down for more than 1 minute"

Install and configure Alertmanager

Set up Alertmanager for handling and routing alerts from Prometheus.

cd /tmp
wget https://github.com/prometheus/alertmanager/releases/download/v0.25.0/alertmanager-0.25.0.linux-amd64.tar.gz
tar xzf alertmanager-0.25.0.linux-amd64.tar.gz
sudo cp alertmanager-0.25.0.linux-amd64/alertmanager /usr/local/bin/
sudo cp alertmanager-0.25.0.linux-amd64/amtool /usr/local/bin/
sudo mkdir -p /etc/alertmanager
sudo chown prometheus:prometheus /usr/local/bin/alertmanager /usr/local/bin/amtool /etc/alertmanager

Configure Alertmanager

Set up Alertmanager configuration for email and webhook notifications.

global:
  smtp_smarthost: 'localhost:587'
  smtp_from: 'alerts@example.com'
  smtp_auth_username: 'alerts@example.com'
  smtp_auth_password: 'your_email_password'

route:
  group_by: ['alertname']
  group_wait: 10s
  group_interval: 10s
  repeat_interval: 1h
  receiver: 'web.hook'

receivers:
  - name: 'web.hook'
    email_configs:
      - to: 'admin@example.com'
        subject: '[ALERT] {{ .GroupLabels.alertname }}'
        body: |
          {{ range .Alerts }}
          Alert: {{ .Annotations.summary }}
          Description: {{ .Annotations.description }}
          Labels: {{ range .Labels.SortedPairs }}{{ .Name }}={{ .Value }} {{ end }}
          {{ end }}
    
inhibit_rules:
  - source_match:
      severity: 'critical'
    target_match:
      severity: 'warning'
    equal: ['alertname', 'dev', 'instance']

Create Alertmanager systemd service

Configure Alertmanager to run as a system service.

[Unit]
Description=Alertmanager
Wants=network-online.target
After=network-online.target

[Service]
User=prometheus
Group=prometheus
Type=simple
ExecStart=/usr/local/bin/alertmanager \
    --config.file=/etc/alertmanager/alertmanager.yml \
    --storage.path=/var/lib/alertmanager/

[Install]
WantedBy=multi-user.target

Set up firewall rules

Configure firewall rules to allow access to monitoring services.

sudo ufw allow 9090/tcp comment 'Prometheus'
sudo ufw allow 3000/tcp comment 'Grafana'
sudo ufw allow 9093/tcp comment 'Alertmanager'
sudo ufw reload

sudo firewall-cmd --permanent --add-port=9090/tcp
sudo firewall-cmd --permanent --add-port=3000/tcp
sudo firewall-cmd --permanent --add-port=9093/tcp
sudo firewall-cmd --reload

Start Alertmanager and restart Prometheus

Enable Alertmanager and restart Prometheus to load the new alerting rules.

sudo mkdir -p /var/lib/alertmanager
sudo chown prometheus:prometheus /var/lib/alertmanager
sudo systemctl daemon-reload
sudo systemctl enable --now alertmanager
sudo systemctl restart prometheus

# Verify services
sudo systemctl status alertmanager
sudo systemctl status prometheus